Ben T
08/06/2025, 6:08 PMMarvin
08/06/2025, 6:08 PMMarvin
08/06/2025, 6:09 PMpython
from prefect import task, flow
@task(
retries=3, # Number of retries
retry_delay_seconds=10 # Delay between retries
)
async def your_task():
# Your task code here
pass
2. More Robust Implementation with Exponential Backoff:
python
from prefect import task, flow
from prefect.tasks import exponential_backoff
@task(
retries=3,
retry_delay_seconds=exponential_backoff(backoff_factor=2), # Will wait 2, 4, 8 seconds
)
async def your_task():
# Your task code here
pass
@flow
async def your_flow():
results = await your_task()
return results
3. Advanced Implementation with Custom Retry Conditions:
python
from prefect import task, flow
def should_retry(exception: Exception) -> bool:
# Retry specifically for the TaskRun state error
return isinstance(exception, AttributeError) and "TaskRun" in str(exception)
@task(
retries=3,
retry_delay_seconds=10,
retry_condition_fn=should_retry
)
async def your_task():
# Your task code here
pass
Important Notes:
1. If you're submitting many tasks simultaneously (as shown in the GitHub issue), consider adding some delay between submissions:
python
@flow
async def your_flow():
tasks = []
for i in range(100):
task = your_task.submit()
tasks.append(task)
await asyncio.sleep(0.1) # Add small delay between submissions
results = [await t.result() for t in tasks]
2. Make sure you're using the latest version of Prefect 3.x, as there have been fixes for concurrent task execution issues.
3. If you're still experiencing issues, you might want to:
- Reduce the number of concurrent tasks
- Implement exponential backoff
- Add proper error handling in your task code
The error you're seeing ("TaskRun object has no attribute 'state'") is a known issue when submitting many tasks simultaneously. The retry mechanism above, combined with the suggested patterns for task submission, should help mitigate this issue.
Would you like me to provide more specific examples based on your particular use case? It would be helpful to see your current task implementation to provide more targeted advice.Ben T
08/06/2025, 6:10 PMMarvin
08/06/2025, 6:10 PMMarvin
08/06/2025, 6:11 PMpython
from prefect import flow, task
import asyncio
from functools import partial
from asyncio import Semaphore
@task(retries=3, retry_delay_seconds=10)
async def your_task():
# your task code here
pass
@flow
async def your_flow():
# Limit concurrent task submissions
sem = Semaphore(10) # Adjust this number based on your needs
async def submit_with_semaphore():
async with sem:
return await your_task.submit()
# Create all task futures
tasks = [submit_with_semaphore() for _ in range(100)]
# Wait for all tasks to complete
results = await asyncio.gather(*tasks)
return results
2. Batch Your Task Submissions:
python
@flow
async def your_flow():
batch_size = 10
all_results = []
# Process in batches
for i in range(0, 100, batch_size):
batch_tasks = [your_task.submit() for _ in range(batch_size)]
batch_results = await asyncio.gather(*batch_tasks)
all_results.extend(batch_results)
# Optional: Add small delay between batches
await asyncio.sleep(1)
return all_results
3. Use Task Groups (recommended approach for Prefect 3.x):
python
from prefect import task, flow
from prefect.tasks import task_input_hash
from datetime import timedelta
@task(
retries=3,
retry_delay_seconds=10,
cache_key_fn=task_input_hash,
cache_expiration=timedelta(minutes=10) # Add caching to help with retries
)
async def your_task(i: int):
# your task code here
pass
@flow
async def your_flow():
async with anyio.create_task_group() as tg:
tasks = []
for i in range(100):
task = tg.start_soon(your_task, i)
tasks.append(task)
await asyncio.sleep(0.1) # Small delay between submissions
return tasks
4. Add Error Boundary Flow:
python
from prefect import flow, task
from prefect.utilities.annotations import quote
@task(retries=3, retry_delay_seconds=10)
async def your_task():
# your task code here
pass
@flow(name="error_boundary_flow")
async def error_boundary_flow(task_fn):
return await task_fn()
@flow
async def main_flow():
tasks = []
for _ in range(100):
# Wrap each task submission in an error boundary
task = await error_boundary_flow(quote(your_task))
tasks.append(task)
return tasks
Additional Recommendations:
1. Make sure you're using the latest version of Prefect 3.x, as there have been improvements to concurrent task handling.
2. Consider adding logging to help debug when this occurs:
python
import logging
@task(retries=3, retry_delay_seconds=10)
async def your_task():
<http://logging.info|logging.info>("Starting task execution")
try:
# your task code here
pass
except Exception as e:
logging.error(f"Task failed with error: {str(e)}")
raise
3. If possible, monitor your system resources (CPU, memory) when this occurs, as it might be related to resource exhaustion when submitting many tasks simultaneously.
Would you like to share your current task implementation so I can provide more specific guidance? Also, it would be helpful to know:
1. How many tasks are you typically submitting at once?
2. What kind of work are these tasks doing?
3. Are you running this locally or in a distributed environment?Ben T
08/06/2025, 6:12 PMMarvin
08/06/2025, 6:12 PMMarvin
08/06/2025, 6:12 PMpython
from prefect import flow
@flow(
retries=3, # Number of retries
retry_delay_seconds=10 # Delay between retries
)
async def your_flow():
# Your flow code here
tasks = [your_task.submit() for _ in range(100)]
results = await asyncio.gather(*tasks)
return results
For more advanced retry control, you can also specify a custom retry policy:
python
from prefect import flow
from datetime import timedelta
def should_retry_flow(exception: Exception) -> bool:
# Retry specifically for the TaskRun state error
return isinstance(exception, AttributeError) and "TaskRun" in str(exception)
@flow(
retries=3,
retry_delay_seconds=exponential_backoff(backoff_factor=2), # Will wait 2, 4, 8 seconds
retry_condition_fn=should_retry_flow
)
async def your_flow():
# Your flow code here
pass
You can also combine this with a context manager to handle cleanup in case of failures:
python
from prefect import flow
from contextlib import asynccontextmanager
@asynccontextmanager
async def flow_error_handler():
try:
yield
except Exception as e:
print(f"Flow failed with error: {str(e)}")
raise
@flow(retries=3, retry_delay_seconds=10)
async def your_flow():
async with flow_error_handler():
tasks = [your_task.submit() for _ in range(100)]
results = await asyncio.gather(*tasks)
return results
This should help catch and retry the flow-level failure you're experiencing. The flow will retry up to 3 times if it encounters the TaskRun state error.
Would you like me to provide more specific guidance based on your particular flow implementation? It would be helpful to see:
1. Your current flow structure
2. The specific error message you're getting
3. Whether you're running this locally or in a distributed environmentBen T
08/06/2025, 6:14 PMMarvin
08/06/2025, 6:14 PMMarvin
08/06/2025, 6:15 PMname
parameter to task decorators:
1. Improved Observability:
python
@task(name="extract_customer_data") # Clear purpose in logs/UI
async def get_data_from_api():
# vs. default name which would be "get_data_from_api"
pass
2. Better Task Identification in Logs and UI:
- Without custom names, tasks with similar function names can be hard to distinguish
- Custom names make it easier to track specific task instances, especially in parallel executions
3. Clearer Error Messages:
python
@task(name="process_user_123")
def process_user(user_id: int):
# Error messages will show "process_user_123 failed" instead of "process_user failed"
pass
4. Version Independence:
python
@task(name="extract_data_v2")
def get_data():
# If you change the function name later, logs/history still show consistent task name
pass
5. Task Reuse Clarity:
python
@task(name="validate_email_address")
def validate(input_str: str):
# More clear than just "validate" when used in different contexts
pass
However, there are some cases where you might NOT want to add a name:
1. When the function name is already clear and descriptive
2. For simple, single-purpose flows where task identification is straightforward
3. When you want to maintain direct correlation between function names and task names
Best Practices for Task Naming:
python
from prefect import task, flow
# Good: When task has multiple instances
@task(name="process_customer_segment_A")
def process_customers(segment: str):
pass
# Good: When function name is generic
@task(name="extract_salesforce_leads")
def extract_data():
pass
# Unnecessary: When function name is already clear
@task
def calculate_monthly_revenue():
pass
# Good: When versioning matters
@task(name="transform_data_v2")
def transform_data():
pass
@flow
def main_flow():
# Now logs and UI will show meaningful task names
segment_a = process_customers("A")
leads = extract_data()
revenue = calculate_monthly_revenue()
The decision to add a name parameter should be based on:
1. Whether the default name (function name) is clear enough
2. If you need to distinguish between multiple instances of similar tasks
3. Whether you want to maintain consistent naming across code changes
4. The complexity of your flow and need for clear task identification
Remember: While naming tasks can be helpful, don't feel obligated to name every task - use names where they add value to understanding, debugging, or maintaining your workflows.Ben T
08/06/2025, 6:17 PMMarvin
08/06/2025, 6:17 PMMarvin
08/06/2025, 6:20 PMpython
from prefect import flow
from prefect.runtime import flow_run
from datetime import datetime
def generate_flow_run_name() -> str:
# Access the flow's name from runtime context
flow_name = flow_run.flow_name
timestamp = datetime.utcnow().strftime("%Y%m%d-%H%M%S")
return f"{flow_name}-{timestamp}"
@flow(name="my-special-flow", flow_run_name=generate_flow_run_name)
def my_flow():
print(f"Current flow run name: {flow_run.flow_run_name}")
2. With Parameters:
python
from prefect import flow
from typing import Optional
def generate_flow_run_name(environment: Optional[str] = None) -> str:
base_name = flow_run.flow_name
env_suffix = f"-{environment}" if environment else ""
return f"{base_name}{env_suffix}-{datetime.utcnow().strftime('%Y%m%d-%H%M%S')}"
@flow(
name="data-pipeline",
flow_run_name=generate_flow_run_name
)
def process_data(environment: str = "dev"):
print(f"Running in {environment}")
3. More Advanced Version with Multiple Parameters:
python
from prefect import flow
from datetime import datetime
from typing import Callable, Optional, Dict, Any
def create_flow_run_namer(
prefix: Optional[str] = None,
date_format: str = "%Y%m%d-%H%M%S",
separator: str = "-"
) -> Callable:
def generate_name(parameters: Dict[str, Any] = None) -> str:
components = []
# Add prefix if specified, otherwise use flow name
name_prefix = prefix or flow_run.flow_name
components.append(name_prefix)
# Add any relevant parameters
if parameters:
for key in sorted(parameters.keys()):
components.append(f"{key}_{parameters[key]}")
# Add timestamp
components.append(datetime.utcnow().strftime(date_format))
return separator.join(components)
return generate_name
@flow(
name="etl-pipeline",
flow_run_name=create_flow_run_namer(prefix="ETL", separator="_")
)
def etl_flow(source: str, destination: str):
print(f"Current flow run name: {flow_run.flow_run_name}")
# Usage:
# etl_flow("postgres", "snowflake")
# Generates names like: ETL_source_postgres_destination_snowflake_20230815-123456
4. With Environment and Version Tracking:
python
from prefect import flow
import platform
import sys
def create_versioned_flow_namer():
def generate_name() -> str:
components = [
flow_run.flow_name,
f"py{sys.version_info.major}.{sys.version_info.minor}",
platform.system().lower(),
datetime.utcnow().strftime("%Y%m%d-%H%M%S")
]
return "-".join(components)
return generate_name
@flow(
name="ml-training",
flow_run_name=create_versioned_flow_namer()
)
def train_model():
# This will create names like: ml-training-py3.9-darwin-20230815-123456
print(f"Running as: {flow_run.flow_run_name}")
5. With Error Handling:
python
from prefect import flow
from prefect.logging import get_run_logger
def safe_flow_run_namer() -> str:
logger = get_run_logger()
try:
base_name = flow_run.flow_name
timestamp = datetime.utcnow().strftime("%Y%m%d-%H%M%S")
return f"{base_name}-{timestamp}"
except Exception as e:
logger.warning(f"Error generating flow run name: {e}")
return f"fallback-flow-{timestamp}"
@flow(name="robust-flow", flow_run_name=safe_flow_run_namer)
def my_robust_flow():
pass
Key points to remember:
1. The flow run name generator has access to flow_run.flow_name
which reflects the name specified in the decorator
2. You can access flow parameters in your naming function
3. The naming function should always return a string
4. Consider adding error handling for robustnessMarvin
08/06/2025, 6:20 PMBen T
08/06/2025, 6:48 PM@flow(
name="build_analytics_tables",
retries=3,
retry_delay_seconds=10
)
Marvin
08/06/2025, 6:48 PMMarvin
08/06/2025, 6:48 PMflow_run.flow_name
would be "build_analytics_tables". Let me demonstrate this with a quick example:
python
from prefect import flow
from prefect.runtime import flow_run
from datetime import datetime
def generate_analytics_run_name() -> str:
# This will be "build_analytics_tables"
flow_name = flow_run.flow_name
timestamp = datetime.utcnow().strftime("%Y%m%d-%H%M%S")
return f"{flow_name}-{timestamp}"
@flow(
name="build_analytics_tables",
retries=3,
retry_delay_seconds=10,
flow_run_name=generate_analytics_run_name
)
def analytics_flow():
print(f"Current flow name: {flow_run.flow_name}") # Will print: "build_analytics_tables"
print(f"Current flow run name: {flow_run.flow_run_name}") # Will print something like: "build_analytics_tables-20230815-123456"
This will generate flow run names like:
- build_analytics_tables-20230815-123456
- build_analytics_tables-20230815-123457
The flow_run.flow_name
always reflects the name
parameter you set in the @flow
decorator, not the function name (analytics_flow
in this case). This is particularly useful when you want to maintain consistent naming in your flow runs while having more descriptive function names in your code.
Would you like to see more examples of how you could customize the flow run naming for your analytics tables flow? For instance, we could include information about which tables are being built or the environment it's running in.Ben T
08/06/2025, 6:50 PMMarvin
08/06/2025, 6:50 PMMarvin
08/06/2025, 6:50 PMcreate_flow_run_namer
) lets us configure how the name generator will work by setting up parameters like prefix
, date_format
, and separator
that will be "remembered" by the inner function.
2. Prefect's Expectation: The flow_run_name
parameter in the @flow
decorator expects either a string or a function that takes an optional parameters dictionary and returns a string.
Here's a breakdown:
python
# Outer function - This is our configuration layer
def create_flow_run_namer(
prefix: Optional[str] = None,
date_format: str = "%Y%m%d-%H%M%S",
separator: str = "-"
) -> Callable:
# Inner function - This is what Prefect actually calls
def generate_name(parameters: Dict[str, Any] = None) -> str:
# This inner function has access to prefix, date_format, and separator
# from the outer function's scope - this is called a "closure"
components = []
name_prefix = prefix or flow_run.flow_name
components.append(name_prefix)
# ... rest of the logic ...
return separator.join(components)
return generate_name
# Usage example:
@flow(
name="my-flow",
# Here we're calling the outer function to get a configured name generator
flow_run_name=create_flow_run_namer(prefix="PROD", separator="_")
)
def my_flow():
pass
Without nesting, you'd have to do something more cumbersome like this:
python
# Without nesting - more rigid and less configurable
def generate_name(parameters: Dict[str, Any] = None) -> str:
# Now these values are hardcoded or would need to be global variables
prefix = "PROD"
date_format = "%Y%m%d-%H%M%S"
separator = "-"
components = []
name_prefix = prefix or flow_run.flow_name
components.append(name_prefix)
# ... rest of the logic ...
return separator.join(components)
@flow(name="my-flow", flow_run_name=generate_name)
def my_flow():
pass
Here's a simpler example to illustrate the pattern:
python
# Example of why closures are useful
def create_greeting(greeting_word: str):
def greet(name: str):
return f"{greeting_word}, {name}!"
return greet
# Create two different greeting functions
say_hello = create_greeting("Hello")
say_hi = create_greeting("Hi")
print(say_hello("Alice")) # "Hello, Alice!"
print(say_hi("Alice")) # "Hi, Alice!"
In your analytics case, you might use it like this:
python
from prefect import flow
from datetime import datetime
from typing import Optional, Dict, Any
def create_analytics_namer(
environment: str = "prod",
include_date: bool = True
):
def generate_name(parameters: Dict[str, Any] = None) -> str:
components = [flow_run.flow_name, environment]
# Add any table names if they're in the parameters
if parameters and "tables" in parameters:
components.append(f"tables_{parameters['tables']}")
# Optionally add date
if include_date:
components.append(datetime.utcnow().strftime("%Y%m%d"))
return "-".join(components)
return generate_name
@flow(
name="build_analytics_tables",
flow_run_name=create_analytics_namer(environment="staging", include_date=True)
)
def build_tables(tables: list):
# This will create names like: build_analytics_tables-staging-tables_['users','orders']-20230815
pass
The nested function pattern gives you:
1. Configuration flexibility without global variables
2. Encapsulation of related functionality
3. The ability to create multiple variants of the name generator with different configurations
4. Compliance with Prefect's expected function signature for flow_run_name
Ben T
08/06/2025, 7:13 PMMarvin
08/06/2025, 7:13 PMMarvin
08/06/2025, 7:15 PMprefect.runtime.flow_run.flow_name
when you want to access the static flow name (the one you set in the decorator). Here's why:
1. flow_run.flow_name
gives you the static name you defined in the @flow
decorator
2. get_run_context().flow_run.name
gives you the dynamic flow run name (which might include timestamps, parameters, etc.)
Here's an example to illustrate the difference:
python
from prefect import flow
from prefect.runtime import flow_run
from datetime import datetime
def generate_run_name() -> str:
# This gets the static flow name ("analytics-pipeline")
base_name = flow_run.flow_name
# This would get the dynamic run name (might be "analytics-pipeline-20230815-123456")
# current_run_name = get_run_context().flow_run.name
timestamp = datetime.utcnow().strftime("%Y%m%d-%H%M%S")
return f"{base_name}-{timestamp}"
@flow(
name="analytics-pipeline",
flow_run_name=generate_run_name
)
def my_analytics_flow():
print(f"Flow name: {flow_run.flow_name}") # Will print: "analytics-pipeline"
print(f"Flow run name: {flow_run.name}") # Will print: "analytics-pipeline-20230815-123456"
Here's a more complete example showing the difference:
python
from prefect import flow
from prefect.runtime import flow_run
from datetime import datetime
from typing import Optional, Dict, Any
def create_analytics_namer(environment: str = "prod"):
def generate_name(parameters: Dict[str, Any] = None) -> str:
# Use flow_run.flow_name to get the static name from the decorator
base_name = flow_run.flow_name
components = [
base_name,
environment,
datetime.utcnow().strftime("%Y%m%d-%H%M%S")
]
if parameters and "table_name" in parameters:
components.insert(1, parameters["table_name"])
return "-".join(components)
return generate_name
@flow(
name="build_analytics_tables",
flow_run_name=create_analytics_namer(environment="staging")
)
def build_table(table_name: str):
print(f"Static flow name: {flow_run.flow_name}")
# Will print: "build_analytics_tables"
print(f"Dynamic flow run name: {flow_run.name}")
# Will print something like: "build_analytics_tables-users-staging-20230815-123456"
Key points:
1. Use flow_run.flow_name
when you want the static name from the decorator
2. Use flow_run.name
when you want the current run's name (which might include dynamic elements)
3. Avoid get_run_context()
as it's less idiomatic in Prefect 3.x
4. The prefect.runtime
module is the preferred way to access runtime information in Prefect 3.x
This approach is more consistent with Prefect 3.x's patterns and will be more maintainable in the long run.Ben T
08/06/2025, 7:17 PMdef generate_flow_run_name(
date_format: str = "%Y%m%d-%H%M%S",
separator: str = "-",
prefix: Optional[str] = None,
parameters: Optional[dict[str, Any]] = None
) -> Callable[[], str]:
"""
Creates a flow run name generator for Prefect flows.
The generated function builds a name by combining:
- A prefix (either provided or from `flow_run.flow_name`)
- Any provided parameters as `key_value` pairs sorted by key
- A UTC timestamp in the given format
:param date_format: A `strftime`-compatible format string for the UTC timestamp. Defaults to "%Y%m%d-%H%M%S".
:param separator: String used to join the name components. Defaults to "-".
:param prefix: Optional static prefix for the flow run name. If None, the flow name (`flow_run.flow_name`) will be used.
:param parameters: Optional dictionary of parameters to include in the run name.
:returns: A zero-argument callable that returns the generated flow run name as a string.
"""
def generate_name() -> str:
components: list[str] = []
# Use explicit prefix if provided, otherwise the flow's name
name_prefix = prefix or flow_run.flow_name
components.append(name_prefix)
# Add parameters in a stable order
if parameters:
for key in sorted(parameters.keys()):
components.append(f"{key}_{parameters[key]}")
# Always add timestamp
components.append(datetime.datetime.now(datetime.UTC).strftime(date_format))
return separator.join(components)
return generate_name
Marvin
08/06/2025, 7:17 PMMarvin
08/06/2025, 7:18 PMpython
def generate_flow_run_name(
date_format: str = "%Y%m%d-%H%M%S",
separator: str = "-",
prefix: Optional[str] = None,
) -> Callable[[Optional[Dict[str, Any]]], str]: # Note the signature change
"""
Creates a flow run name generator for Prefect flows.
:param date_format: A `strftime`-compatible format string for the UTC timestamp. Defaults to "%Y%m%d-%H%M%S".
:param separator: String used to join the name components. Defaults to "-".
:param prefix: Optional static prefix for the flow run name. If None, the flow name (`flow_run.flow_name`) will be used.
:returns: A callable that accepts an optional parameters dict and returns the generated flow run name as a string.
"""
def generate_name(parameters: Optional[Dict[str, Any]] = None) -> str: # Prefect passes parameters here
components: list[str] = []
# Use explicit prefix if provided, otherwise the flow's name
name_prefix = prefix or flow_run.flow_name
components.append(name_prefix)
# Add parameters in a stable order
if parameters:
for key in sorted(parameters.keys()):
components.append(f"{key}_{parameters[key]}")
# Always add timestamp
components.append(datetime.datetime.now(datetime.UTC).strftime(date_format))
return separator.join(components)
return generate_name
2. Parameter Value Formatting: You might want to add some safety around parameter value formatting:
python
def generate_flow_run_name(
date_format: str = "%Y%m%d-%H%M%S",
separator: str = "-",
prefix: Optional[str] = None,
) -> Callable[[Optional[Dict[str, Any]]], str]:
def generate_name(parameters: Optional[Dict[str, Any]] = None) -> str:
components: list[str] = []
# Use explicit prefix if provided, otherwise the flow's name
name_prefix = prefix or flow_run.flow_name
components.append(name_prefix)
# Add parameters in a stable order
if parameters:
for key in sorted(parameters.keys()):
# Safe string conversion and cleanup
value = str(parameters[key]).replace(" ", "").replace(separator, "_")
components.append(f"{key}_{value}")
# Always add timestamp
components.append(datetime.datetime.now(datetime.UTC).strftime(date_format))
return separator.join(components)
return generate_name
Usage example:
python
@flow(
name="analytics-pipeline",
flow_run_name=generate_flow_run_name(
prefix="ANALYTICS",
date_format="%Y%m%d",
separator="_"
)
)
def process_data(table_name: str, date: str):
# This will generate names like:
# ANALYTICS_table_name_users_date_20230815_20230815
pass
3. Optional Enhancement: You might want to add parameter filtering:
```python
def generate_flow_run_name(
date_format: str = "%Y%m%d-%H%M%S",
separator: str = "-",
prefix: Optional[str] = None,
include_params: Optional[list[str]] = None, # Only include these parameters
) -> Callable[[Optional[Dict[str, Any]]], str]:
def generate_name(parameters: Optional[Dict[str, Any]] = None) -> str:
components: list[str] = []
name_prefix = prefix or flow_run.flow_name
components.append(name_prefix)
if parameters:
filtered_params = {
k: v for k, v in parameters.items()
if include_params is None or k in include_params
}
for key in sorted(filtered_params.keys()):Marvin
08/06/2025, 7:18 PM4. *Error Handling*: You might want to add some error handling:
```python
from prefect.logging import get_run_logger
def generate_flow_run_name(
date_format: str = "%Y%m%d-%H%M%S",
separator: str = "-",
prefix: Optional[str] = None,
) -> Callable[[Optional[Dict[str, Any]]], str]:
def generate_name(parameters: Optional[Dict[str, Any]] = None) -> str:
logger = get_run_logger()
try:
components: list[str] = []
name_prefix = prefix or flow_run.flow_name
components.append(name_prefix)
if parameters:
for key in sorted(parameters.keys()):
try:
value = str(parameters[key]).replace(" ", "").replace(separator, "_")
components.append(f"{key}_{value}")
except Exception as e:
logger.warning(f"Failed to format parameter {key}: {e}")
components.append(datetime.datetime.now(datetime.UTC).strftime(date_format))
return separator.join(components)
except Exception as e:
logger.error(f"Error generating flow run name: {e}")
# Fallback to a simple name
return f"{flow_run.flow_name}-{datetime.datetime.now(datetime.UTC).strftime(date_format)}"
return generate_name
The main change needed is to move the parameters argument from the outer function to the inner function, as Prefect will pass the flow parameters to the name generator function at runtime. The other suggestions are enhancements that might be useful depending on your specific needs.
Would you like me to explain any of these modifications in more detail?Ben T
08/06/2025, 7:21 PMdef generate_flow_run_name(
date_format: str = "%Y%m%d-%H%M%S",
separator: str = "-",
prefix: Optional[str] = None
) -> Callable[[Optional[dict[str, Any]]], str]:
"""
Creates a flow run name generator for Prefect flows.
The generated function builds a name by combining:
- A prefix (either provided or from `flow_run.flow_name`)
- Any provided parameters as `key_value` pairs sorted by key
- A UTC timestamp in the given format
:param date_format: A `strftime`-compatible format string for the UTC timestamp. Defaults to "%Y%m%d-%H%M%S".
:param separator: String used to join the name components. Defaults to "-".
:param prefix: Optional static prefix for the flow run name. If None, the flow name (`flow_run.flow_name`) will be used.
:returns: A callable that accepts an optional parameters dict and returns the generated flow run name as a string.
"""
def generate_name(
parameters: Optional[dict[str, Any]] = None
) -> str:
"""
Generate a Prefect flow run name.
Builds a name by combining:
- A prefix (either provided to the factory or from `flow_run.flow_name`)
- Any provided parameters as `key_value` pairs sorted by key
- A UTC timestamp in the configured format
:param parameters: Optional dictionary of flow parameters to include in the name.
Keys are sorted alphabetically; values are converted to strings
with spaces removed and separators replaced with underscores.
:returns: The generated flow run name as a string.
"""
components: list[str] = []
# Use explicit prefix if provided, otherwise the flow's name
name_prefix = prefix or flow_run.flow_name
components.append(name_prefix)
# Add parameters in a stable order
if parameters:
for key in sorted(parameters.keys()):
# Safe string conversion
value = str(parameters[key]).replace(" ", "").replace(separator, "_")
components.append(f"{key}_{value}")
# Always add timestamp (UTC-aware)
components.append(datetime.datetime.now(datetime.UTC).strftime(date_format))
return separator.join(components)
return generate_name
Marvin
08/06/2025, 7:21 PMMarvin
08/06/2025, 7:21 PMpython
from prefect.logging import get_run_logger
def generate_name(parameters: Optional[dict[str, Any]] = None) -> str:
logger = get_run_logger()
try:
# ... your existing code ...
except Exception as e:
logger.warning(f"Error generating flow run name: {e}")
# Fallback to basic name
return f"{flow_run.flow_name}-{datetime.datetime.now(datetime.UTC).strftime(date_format)}"
2. Parameter filtering if you want to control which parameters appear in the name:
python
def generate_flow_run_name(
date_format: str = "%Y%m%d-%H%M%S",
separator: str = "-",
prefix: Optional[str] = None,
include_params: Optional[list[str]] = None, # New optional parameter
) -> Callable[[Optional[dict[str, Any]]], str]:
But these are purely optional and depend on your specific needs. Your current implementation is solid and ready to use! Here's how it would work in practice:
python
@flow(
name="analytics-pipeline",
flow_run_name=generate_flow_run_name(
prefix="ANALYTICS",
date_format="%Y%m%d",
separator="_"
)
)
def process_data(table_name: str, date: str):
# Will generate names like:
# ANALYTICS_table_name_users_date_20230815_20230815
pass
Ben T
08/06/2025, 7:24 PMMarvin
08/06/2025, 7:24 PMMarvin
08/06/2025, 7:27 PMMarvin
08/06/2025, 7:28 PMprefect.utilities.names.generate_slug()
. Here's how to use it:
python
from prefect.utilities.names import generate_slug
# Generate a random name (like "jumping-rabbit")
random_name = generate_slug(2) # 2 words
# Use it in a flow run name generator
from prefect import flow
from datetime import datetime
from typing import Optional, Dict, Any
def generate_flow_run_name(
include_random_name: bool = True,
separator: str = "-"
) -> Callable[[Optional[Dict[str, Any]]], str]:
def generate_name(parameters: Optional[Dict[str, Any]] = None) -> str:
components = []
# Add base flow name
components.append(flow_run.flow_name)
# Add random animal-style name if requested
if include_random_name:
components.append(generate_slug(2))
# Add timestamp
components.append(datetime.datetime.now(datetime.UTC).strftime("%Y%m%d-%H%M%S"))
return separator.join(components)
return generate_name
@flow(
name="analytics-pipeline",
flow_run_name=generate_flow_run_name(include_random_name=True)
)
def process_data():
# This will generate names like:
# analytics-pipeline-jumping-rabbit-20230815-123456
pass
Or if you just want to see what names it generates:
python
from prefect.utilities.names import generate_slug
# Generate a few example names
for _ in range(5):
print(generate_slug(2))
# Might output something like:
# jumping-rabbit
# dancing-penguin
# flying-elephant
# happy-tiger
# running-giraffe
The generate_slug()
function is what Prefect uses internally to generate those friendly names you see in the UI. You can specify the number of words you want in the name by passing a number to the function.
Would you like me to show you more examples of how to incorporate this into your flow run naming strategy?Ben T
08/06/2025, 7:32 PMMarvin
08/06/2025, 7:32 PMMarvin
08/06/2025, 7:33 PMgenerate_slug
is NOT what's typically used for default flow run names.
In Prefect 3.x, by default:
1. If you don't specify a flow_run_name
, Prefect will use a combination of the flow name and a timestamp
2. generate_slug
is more commonly used for generating random names for other purposes (like work pool names, deployment names, etc.)
Here's a clearer picture:
python
from prefect import flow
# Default behavior - will use flow name + timestamp
@flow(name="my-analytics")
def process_data():
pass
# Results in names like: "my-analytics-20230815-123456"
# If you want the animal-style names, you'd need to explicitly use generate_slug
from prefect.utilities.names import generate_slug
@flow(
name="my-analytics",
flow_run_name=lambda: f"{generate_slug(2)}-{datetime.datetime.now(datetime.UTC).strftime('%Y%m%d-%H%M%S')}"
)
def process_data():
pass
# Results in names like: "happy-penguin-20230815-123456"
The standard pattern for flow run names typically follows:
1. Flow name (from the name
parameter in the decorator)
2. Any additional identifiers you want to add
3. Timestamp for uniqueness
Your earlier implementation with the generate_flow_run_name
function is actually more in line with typical Prefect usage than using generate_slug
. The generate_slug
function is available as a utility but isn't the standard way to name flow runs.
Would you like me to show you some other common patterns for flow run naming in Prefect 3.x?Ben T
08/06/2025, 7:36 PMMarvin
08/06/2025, 7:36 PMMarvin
08/06/2025, 7:37 PMget_run_logger()
outside a flow and pass it in. Here's why:
1. Context Dependency: The logger from get_run_logger()
needs a run context to function properly
2. Runtime Issues: Initializing it outside a flow will either raise a MissingContextError
or not properly associate logs with the correct flow run
Here's what you should do instead:
python
from prefect import flow, task
from prefect.logging import get_run_logger
# ❌ Don't do this:
logger = get_run_logger() # This will fail or not work as expected
@flow
def my_flow(logger): # Don't pass logger as parameter
<http://logger.info|logger.info>("Hello") # Logs won't be properly associated with the flow run
# ✅ Do this instead:
@flow
def my_flow():
logger = get_run_logger() # Initialize inside the flow
<http://logger.info|logger.info>("Hello") # Properly associated with flow run
# ✅ For tasks:
@task
def my_task():
logger = get_run_logger() # Initialize inside the task
<http://logger.info|logger.info>("Task running")
# ✅ If you need logging outside of flows/tasks:
from prefect.logging import get_logger
setup_logger = get_logger("setup") # Use get_logger instead of get_run_logger
<http://setup_logger.info|setup_logger.info>("Setting up...")
If you need to share logging functionality across multiple components, consider creating a function that gets the logger:
python
from prefect import flow, task
from prefect.logging import get_run_logger
from typing import Any
def log_step(step_name: str, data: Any = None) -> None:
logger = get_run_logger()
<http://logger.info|logger.info>(f"Step: {step_name}", extra={"data": data})
@flow
def my_flow():
log_step("Starting flow")
result = process_data()
log_step("Data processed", result)
@task
def process_data():
log_step("Processing data")
return {"status": "complete"}
Or if you need more structured logging:
python
from prefect import flow, task
from prefect.logging import get_run_logger
from dataclasses import dataclass
from typing import Optional
@dataclass
class LogContext:
step: str
details: Optional[dict] = None
def log_event(context: LogContext, level: str = "INFO") -> None:
logger = get_run_logger()
log_func = getattr(logger, level.lower())
log_func(f"Step: {context.step}", extra={"details": context.details})
@flow
def my_flow():
log_event(LogContext("flow_start"))
result = process_data()
log_event(LogContext("flow_end", {"result": result}))
@task
def process_data():
log_event(LogContext("processing_data"))
return {"status": "complete"}
The key points to remember are:
1. Always initialize get_run_logger()
inside flows or tasks
2. Use get_logger()
for logging outside of flow/task contexts
3. If you need shared logging logic, create functions that get the logger when needed
4. Consider creating structured logging helpers that initialize the logger at the point of use
Would you like me to show you more patterns for handling logging in Prefect 3.x flows?Ben T
08/07/2025, 4:00 AMMarvin
08/07/2025, 4:00 AMMarvin
08/07/2025, 4:01 AMpython
from prefect.blocks.notifications import SlackWebhook
slack_block = SlackWebhook(
url="<https://hooks.slack.com/services/xxx/yyy/zzz>"
)
slack_block.save(name="basic-slack-webhook")
2. Slack Incoming Webhook Block:
- Part of the prefect-slack
integration package
- More feature-rich implementation
- Supports additional Slack-specific features
- Requires installation of additional package
- Better suited for automation actions and more complex notifications
python
# First install: pip install prefect-slack
from prefect_slack import SlackIncomingWebhook
slack_block = SlackIncomingWebhook(
url="<https://hooks.slack.com/services/xxx/yyy/zzz>"
)
slack_block.save(name="advanced-slack-webhook")
Key Differences:
1. Package Source:
- `SlackWebhook`: Core Prefect package
- `SlackIncomingWebhook`: prefect-slack
integration package
2. Setup Requirements:
- `SlackWebhook`: No additional installation needed
- `SlackIncomingWebhook`: Requires pip install prefect-slack
3. Registration:
- SlackIncomingWebhook
needs explicit registration:
bash
prefect block register -m prefect_slack
4. Usage Context:
python
# Basic Webhook
from prefect.blocks.notifications import SlackWebhook
slack = SlackWebhook.load("basic-slack-webhook")
slack.notify("Simple message")
# Incoming Webhook (more features)
from prefect_slack import SlackIncomingWebhook
slack = SlackIncomingWebhook.load("advanced-slack-webhook")
# Supports more Slack-specific features
await slack.notify_on_failure(flow_run)
await slack.notify_on_completion(flow_run)
5. Automation Support:
- SlackIncomingWebhook
is better suited for automation actions but requires proper setup in server environments
- SlackWebhook
is simpler but has fewer features
Best Practices:
1. Use SlackWebhook
for:
- Simple notifications
- Basic setups
- When you don't need advanced Slack features
2. Use SlackIncomingWebhook
for:
- Automation actions
- More complex notification needs
- When you need Slack-specific features
- When you're using the broader Slack integration capabilities
Remember to handle the setup appropriately, especially in server environments:
bash
# When using SlackIncomingWebhook, always register the blocks
prefect block register -m prefect_slack
# Verify registration
prefect block type ls
Would you like me to provide more specific examples of how to use either block type in your workflows?Ben T
08/07/2025, 4:12 AMMarvin
08/07/2025, 4:12 AMMarvin
08/07/2025, 4:13 AMprefect.runtime
module. Here's a comprehensive overview:
1. Flow Run Context:
python
from prefect import flow
from prefect.runtime import flow_run
@flow
def my_flow():
# Flow run details
print(f"Flow Run ID: {flow_run.id}")
print(f"Flow Name: {flow_run.flow_name}")
print(f"Flow Run Name: {flow_run.name}")
print(f"Parameters: {flow_run.parameters}")
print(f"Tags: {flow_run.tags}")
print(f"UI URL: {flow_run.ui_url}")
# Parent/Root flow information
print(f"Parent Flow Run ID: {flow_run.parent_flow_run_id}")
print(f"Root Flow Run ID: {flow_run.root_flow_run_id}")
# Deployment information
print(f"Parent Deployment ID: {flow_run.parent_deployment_id}")
# Timing information
print(f"Scheduled Start: {flow_run.scheduled_start_time}")
# Run metadata
print(f"Run Count: {flow_run.run_count}")
print(f"Flow Version: {flow_run.flow_version}")
2. Task Run Context:
python
from prefect import task
from prefect.runtime import task_run
@task
def my_task():
print(f"Task Run ID: {task_run.id}")
print(f"Task Name: {task_run.task_name}")
print(f"Task Run Name: {task_run.name}")
print(f"Parameters: {task_run.parameters}")
print(f"Tags: {task_run.tags}")
print(f"UI URL: {task_run.ui_url}")
print(f"Run Count: {task_run.run_count}")
3. Deployment Context:
python
from prefect import flow
from prefect.runtime import deployment
@flow
def my_flow():
if deployment.id: # Only available when run from deployment
print(f"Deployment ID: {deployment.id}")
print(f"Deployment Name: {deployment.name}")
print(f"Deployment Version: {deployment.version}")
print(f"Deployment Parameters: {deployment.parameters}")
4. Practical Example:
python
from prefect import flow, task
from prefect.runtime import flow_run, task_run
from datetime import datetime
def get_context_info():
"""Helper to get relevant context info"""
context = {
"timestamp": datetime.utcnow().isoformat(),
"flow_name": flow_run.flow_name,
"flow_run_id": flow_run.id,
"flow_run_name": flow_run.name,
}
# Add task info if in task context
try:
context.update({
"task_name": task_run.task_name,
"task_run_id": task_run.id
})
except RuntimeError:
pass # Not in task context
# Add deployment info if available
if deployment.id:
context.update({
"deployment_name": deployment.name,
"deployment_id": deployment.id
})
return context
@task
def process_data():
context = get_context_info()
print(f"Processing with context: {context}")
# Your task logic here
@flow
def my_flow():
context = get_context_info()
print(f"Flow started with context: {context}")
process_data()
5. Using Context in Error Handling:
python
from prefect import flow
from prefect.runtime import flow_run
from prefect.logging import get_run_logger
@flow
def my_flow():
logger = get_run_logger()
try:
# Your flow logic here
raise ValueError("Something went wrong")
except Exception as e:
logger.error(
f"Error in flow run {flow_run.name} ({flow_run.id})",
extra={
"flow_run_url": flow_run.ui_url,
"parameters": flow_run.parameters,
"error": str(e)
}
)
raise
These context variables are particularly useful for:
- Logging and debugging
- Creating unique identifiers
- Building URLs to the Prefect UI
- Accessing run-specific parameters
- Understanding the execution hierarchy
- Tracking deployment information
Would you like me to show more specific examples of how to use these context variables in your workflows?Ben T
08/07/2025, 4:14 AMtry:
# Test the block directly
slack_webhook = await SlackWebhook.load("slack-notifications")
await slack_webhook.notify("Test message")
logger.debug("✅ Test Slack notification sent successfully")
except Exception as e:
logger.exception(f"❌ Failed to send test Slack notification: {e}")
Failed to send test Slack notification: Unable to find block document named slack-notifications for block type slack-webhookMarvin
08/07/2025, 4:14 AMMarvin
08/07/2025, 4:14 AMUnable to find block document named slack-notifications for block type slack-webhook
suggests that either:
1. The block hasn't been saved with that name, or
2. The block type name is incorrect (case sensitive)
Here's how to fix it:
1. First, let's check how the block was saved:
python
from prefect.blocks.notifications import SlackWebhook
# When you saved the block, it should have been like this:
slack_webhook = SlackWebhook(
url="your-webhook-url"
)
slack_webhook.save(name="slack-notifications") # This is the name you're trying to load
2. To verify the block exists and its exact name:
python
# You can run this in a Python shell or script
from prefect.blocks.notifications import SlackWebhook
# List all saved blocks of this type
blocks = SlackWebhook.load_all()
for block in blocks:
print(f"Found block: {block.name}")
3. Here's the corrected version of your code:
python
from prefect.blocks.notifications import SlackWebhook
from prefect.logging import get_run_logger
logger = get_run_logger()
try:
# Make sure the block name matches EXACTLY what you saved it as
slack_webhook = await SlackWebhook.load("slack-notifications")
await slack_webhook.notify("Test message")
logger.debug("✅ Test Slack notification sent successfully")
except Exception as e:
logger.exception(f"❌ Failed to send test Slack notification: {e}")
If you're still having issues, you can:
1. List all block types and their saved instances:
python
from prefect.blocks.core import Block
# List all blocks
for block in Block.list_blocks():
print(block)
2. Or check via CLI:
bash
prefect block ls
3. If you need to create the block, you can do it programmatically:
python
from prefect.blocks.notifications import SlackWebhook
# Create and save the block
slack_webhook = SlackWebhook(
url="your-webhook-url"
)
slack_webhook.save(name="slack-notifications", overwrite=True) # overwrite=True if you want to update existing
# Then try loading and using it
loaded_webhook = await SlackWebhook.load("slack-notifications")
await loaded_webhook.notify("Test message")
4. Or create it via the Prefect UI:
- Go to Blocks in the UI
- Click "Add Block"
- Select "Slack Webhook"
- Enter your webhook URL
- Save it with the name "slack-notifications"
Would you like me to help you troubleshoot further? It would be helpful to know:
1. How did you initially create/save the block?
2. What does prefect block ls
show?
3. Are you using any specific naming convention in your block management?Ben T
08/07/2025, 4:15 AMfrom prefect.blocks.notifications import SlackWebhook
Marvin
08/07/2025, 4:15 AMMarvin
08/07/2025, 4:16 AMpython
from prefect.blocks.notifications import SlackWebhook
from prefect.blocks.core import Block
from prefect.logging import get_run_logger
logger = get_run_logger()
# First, let's check what blocks are available
all_blocks = Block.list_blocks()
<http://logger.info|logger.info>(f"Available blocks: {all_blocks}")
# Then check specifically for slack webhooks
slack_blocks = SlackWebhook.load_all()
<http://logger.info|logger.info>(f"Available Slack webhook blocks: {[block.name for block in slack_blocks]}")
try:
# Load using the full block type path
slack_webhook = await SlackWebhook.load("slack-webhook/slack-notifications")
await slack_webhook.notify("Test message")
logger.debug("✅ Test Slack notification sent successfully")
except Exception as e:
logger.exception(f"❌ Failed to send test Slack notification: {e}")
If that doesn't work, let's try creating a new block to ensure it's registered correctly:
python
from prefect.blocks.notifications import SlackWebhook
from prefect.logging import get_run_logger
logger = get_run_logger()
# Create and save the block
slack_webhook = SlackWebhook(
url="your-webhook-url" # Replace with your actual webhook URL
)
# Save with explicit block type
try:
slack_webhook.save(name="slack-notifications", overwrite=True)
<http://logger.info|logger.info>("Block saved successfully")
# Now try to load and use it
loaded_webhook = await SlackWebhook.load("slack-notifications")
await loaded_webhook.notify("Test message")
logger.debug("✅ Test Slack notification sent successfully")
except Exception as e:
logger.exception(f"❌ Error: {e}")
Can you try running this diagnostic code to help us understand what's happening:
python
from prefect.blocks.notifications import SlackWebhook
from prefect.blocks.core import Block
from prefect.logging import get_run_logger
async def diagnose_slack_block():
logger = get_run_logger()
# 1. Check all available blocks
<http://logger.info|logger.info>("Checking all available blocks...")
all_blocks = Block.list_blocks()
<http://logger.info|logger.info>(f"Available blocks: {all_blocks}")
# 2. Check specifically for slack blocks
<http://logger.info|logger.info>("Checking Slack webhook blocks...")
try:
slack_blocks = SlackWebhook.load_all()
<http://logger.info|logger.info>(f"Found Slack blocks: {[block.name for block in slack_blocks]}")
except Exception as e:
logger.error(f"Error loading Slack blocks: {e}")
# 3. Try different loading approaches
try:
# Try with just the name
<http://logger.info|logger.info>("Trying to load with just name...")
block1 = await SlackWebhook.load("slack-notifications")
<http://logger.info|logger.info>("Success!")
except Exception as e:
logger.error(f"Failed with name only: {e}")
try:
# Try with full path
<http://logger.info|logger.info>("Trying to load with full path...")
block2 = await SlackWebhook.load("slack-webhook/slack-notifications")
<http://logger.info|logger.info>("Success!")
except Exception as e:
logger.error(f"Failed with full path: {e}")
# Use this in your flow
@flow
async def test_flow():
await diagnose_slack_block()
This will help us understand:
1. What blocks are actually available
2. How the Slack block is registered
3. What loading method works
Can you run this diagnostic code and share the output? That will help us pinpoint exactly what's wrong and how to fix it.Ben T
08/07/2025, 4:22 AMfrom prefect_slack import SlackWebhook
slack_webhook_url = os.environ["SLACK_WEBHOOK_URL"]
block_name = "slack-notifications"
def create_slack_webhook_block():
block = SlackWebhook(
url=SecretStr(slack_webhook_url)
)
block.save(block_name, overwrite=True)
<http://logger.info|logger.info>(f"✅ Saved SlackWebhook notification block as '{block_name}'")
Marvin
08/07/2025, 4:22 AMMarvin
08/07/2025, 4:22 AMprefect_slack
but trying to load with prefect.blocks.notifications
. These are different implementations. Let's fix the loading code to match how you created it:
python
from prefect_slack import SlackWebhook # Note: same import as creation
from prefect.logging import get_run_logger
logger = get_run_logger()
try:
# Load using the same SlackWebhook class from prefect_slack
slack_webhook = await SlackWebhook.load("slack-notifications")
await slack_webhook.notify("Test message")
logger.debug("✅ Test Slack notification sent successfully")
except Exception as e:
logger.exception(f"❌ Failed to send test Slack notification: {e}")
The key differences:
1. ❌ from prefect.blocks.notifications import SlackWebhook
# Wrong for your case
2. ✅ from prefect_slack import SlackWebhook
# Correct, matches your creation code
This is happening because:
1. prefect_slack
is a separate package with its own implementation of SlackWebhook
2. The block type is registered under `prefect_slack`'s namespace
3. When you try to load with prefect.blocks.notifications.SlackWebhook
, it's looking for a different block type
Make sure you:
1. Have prefect-slack
installed:
bash
pip install prefect-slack
2. Have registered the blocks:
bash
prefect block register -m prefect_slack
3. Use consistent imports between creation and usage:
python
# Both creation and usage should use the same import:
from prefect_slack import SlackWebhook
Would you like me to show you more examples of how to use the prefect_slack
webhook implementation?Ben T
08/07/2025, 4:23 AMMarvin
08/07/2025, 4:23 AMMarvin
08/07/2025, 4:24 AMprefect_slack.SlackWebhook
2. You were trying to load it with prefect.blocks.notifications.SlackWebhook
3. These are different implementations, even though they have the same class name
It's like trying to open a file with the wrong program - the file exists, but you need to use the right tool to open it.
Here's a visual of what happened:
python
# How you CREATED the block:
from prefect_slack import SlackWebhook # ✅ Created with this implementation
block = SlackWebhook(url=SecretStr(slack_webhook_url))
block.save("slack-notifications")
# How you tried to LOAD the block:
from prefect.blocks.notifications import SlackWebhook # ❌ Different implementation
await SlackWebhook.load("slack-notifications") # Failed because wrong implementation
# How it SHOULD be:
from prefect_slack import SlackWebhook # ✅ Same implementation as creation
await SlackWebhook.load("slack-notifications") # Works!
This is a common gotcha because:
1. The class names are identical
2. Both are part of the Prefect ecosystem
3. Both handle Slack notifications
Best practice is to stay consistent with your imports between creation and usage of blocks.Ben T
08/07/2025, 4:25 AMMarvin
08/07/2025, 4:25 AMMarvin
08/07/2025, 4:26 AMbash
# Make sure the Slack blocks are registered
prefect block register -m prefect_slack
2. Block Type Verification:
python
from prefect.blocks.core import Block
# List all registered block types to verify
blocks = Block.list_blocks()
print([b for b in blocks if "slack" in b.lower()])
3. Automation Configuration:
- Make sure you're using the correct block type in the automation
- For prefect-slack
blocks, use "Slack Incoming Webhook" (not "Slack Webhook")
- The block should be visible in the UI under Blocks
4. Common Fixes:
python
from prefect_slack import SlackWebhook
# 1. Try recreating the block with a different name
slack_webhook = SlackWebhook(
url=SecretStr(slack_webhook_url)
)
slack_webhook.save("slack-notifications-new", overwrite=True)
# 2. Update your automation to use the new block
5. Debugging Steps:
- Check the automation logs in the UI
- Verify the trigger conditions are being met
- Ensure the block is accessible to the automation
Can you check:
1. What block type is selected in your automation?
2. Are you seeing any error messages in the automation logs?
3. Is the trigger condition being met (can you see the automation being triggered)?
This will help us pinpoint exactly why the automation isn't sending notifications even though the webhook works directly.Ben T
08/07/2025, 4:27 AMMarvin
08/07/2025, 4:27 AMMarvin
08/07/2025, 4:27 AMYour Flow Code Prefect Server
------------- --------------
@flow Automation
def my_flow(): - Trigger (e.g., "flow run completed")
# No Slack imports - Action (uses saved Slack block)
# needed here!
pass ↓
Sends Slack notification
The only time you need to import and use the Slack webhook directly in your flow code is if you want to send notifications programmatically from within the flow itself. For automation-based notifications, the block just needs to exist and be properly configured in your Prefect environment.
Would you like me to show you examples of different ways to set up automation triggers for your notifications?Ben T
08/07/2025, 4:44 AMMarvin
08/07/2025, 4:44 AMMarvin
08/07/2025, 4:45 AMprefect-slack
)
- The block name referenced in the automation
- The permissions/access of the automation to use the block
Would you like me to show you specific commands to check these logs, or would you prefer guidance on where to look in the UI?Ben T
08/07/2025, 4:45 AM{
"id": "068942ee-8b45-79e0-8000-091a20f4cd3d",
"event": "prefect.automation.action.failed",
"occurred": "2025-08-07T04:43:20.704Z",
"payload": {
"reason": "The notification block was invalid: UnknownBlockType(\"No block class found for slug 'slack-incoming-webhook'. Please ensure that the block class is available in the current environment.\")",
"invocation": "068942ee-8990-760f-8000-05a59512b651",
"action_type": "send-notification",
"action_index": 0
},
"received": "2025-08-07T04:43:20.704Z",
"related": [],
"resource": {
"prefect.posture": "Reactive",
"prefect.resource.id": "prefect.automation.96eaa544-0481-42f1-b493-9b9ac95745d5",
"prefect.trigger-type": "event",
"prefect.resource.name": "Flow run slack alerts"
}
}
Marvin
08/07/2025, 4:45 AMMarvin
08/07/2025, 4:45 AM"No block class found for slug 'slack-incoming-webhook'. Please ensure that the block class is available in the current environment."
This means the Prefect server doesn't have the prefect-slack
blocks registered. Even though your local environment can use the webhook (which is why the test worked), the server needs the blocks registered too.
Here's how to fix it:
1. Register the blocks on the server:
bash
prefect block register -m prefect_slack
2. Verify the registration:
bash
prefect block type ls
Look for slack-incoming-webhook
in the list.
3. In your automation:
- Make sure you're using "Slack Incoming Webhook" (not "Slack Webhook") as the block type
- The block name should match exactly what you saved it as ("slack-notifications")
If you're running Prefect server in a container or different environment, you need to:
1. Install prefect-slack
in that environment
2. Register the blocks in that environment
3. Restart the server to ensure it picks up the new block types
The reason your test worked but automation didn't:
- Test: Runs in your local environment where prefect-slack
is installed and blocks are registered
- Automation: Runs on the Prefect server where the blocks weren't registered
Would you like me to show you how to verify the block registration on the server side?Ben T
08/07/2025, 4:48 AMMarvin
08/07/2025, 4:48 AMMarvin
08/07/2025, 4:48 AMUnknownBlockType
for 'slack-incoming-webhook'
This suggests there's a mismatch in how the block is being referenced. Since we know the server can use the block (your test worked), let's check:
1. What block type is selected in your automation?
- In the UI, when setting up the automation action
- It should match EXACTLY how you created it: if you used prefect_slack.SlackWebhook
, you need "Slack Webhook" (not "Slack Incoming Webhook")
2. Check your block's actual type:
python
from prefect_slack import SlackWebhook
block = SlackWebhook.load("slack-notifications")
print(f"Block type: {block._block_type_slug}") # This will show the actual block type slug
The error suggests the automation is looking for 'slack-incoming-webhook' but your working block might be registered as 'slack-webhook' or something else.
Could you check:
1. What block type is selected in your automation UI?
2. Can you show the code you used to create the block again?
This will help us align the automation's expected block type with how you actually created it.Ben T
08/07/2025, 4:49 AMblock_type_name
in the db is Slack Incoming Webhook
slack-notifications,"""***""",c7f4a527-f22d-477f-9bd9-b17198ff8eaf,7ecde64e-35ef-41e3-b369-d1e1992eb131,false,Slack Incoming Webhook
Marvin
08/07/2025, 4:49 AMMarvin
08/07/2025, 4:49 AMprefect_slack.SlackWebhook
, there might be a version or registration mismatch.
Let's verify the exact setup:
1. Check what version of prefect-slack
you're using:
bash
pip show prefect-slack
2. Let's try recreating the block with the explicit correct type:
python
from prefect_slack.webhooks import SlackWebhook # Note the .webhooks import
# or
from prefect_slack import SlackIncomingWebhook # Depending on your version
slack_webhook = SlackIncomingWebhook( # Note: IncomingWebhook, not just Webhook
url=SecretStr(slack_webhook_url)
)
slack_webhook.save("slack-notifications", overwrite=True)
The fact that:
- The test works
- The DB shows "Slack Incoming Webhook"
- But automation fails with "slack-incoming-webhook" slug error
Suggests there might be a mismatch between how the block is registered and how the automation system is trying to use it.
Could you share:
1. The output of pip show prefect-slack
2. Whether you're using SlackWebhook
or SlackIncomingWebhook
in your creation code?
This will help us ensure everything aligns correctly.Ben T
08/07/2025, 4:52 AMMarvin
08/07/2025, 4:52 AMMarvin
08/07/2025, 4:53 AMpython
from prefect.blocks.notifications import SlackWebhook # Note: different import
slack_webhook = SlackWebhook(
url=SecretStr(slack_webhook_url)
)
slack_webhook.save("slack-notifications-core", overwrite=True)
2. Update your automation to use this new block (in the UI):
- Edit the automation
- Change the notification block to use the new "slack-notifications-core" block
- Make sure to select "Slack Webhook" (not "Slack Incoming Webhook") as the block type
This should resolve the UnknownBlockType
error and get your automation notifications working. The core SlackWebhook
block is fully supported in automations, while the integration package's webhook has this known limitation.
Would you like me to show you how to migrate your existing notifications to use the core webhook block?Ben T
08/07/2025, 4:53 AMMarvin
08/07/2025, 4:54 AMMarvin
08/07/2025, 4:54 AMNotificationBlock
types for automation actions"
2. Related issue with the same error:
https://github.com/PrefectHQ/prefect/issues/16336
"Automation Action Type Send a notification
fails when using Slack Incoming Webhook block"
3. Another related issue with detailed reproduction steps:
https://github.com/PrefectHQ/prefect/issues/15302
"KeyError('No class found for dispatch key 'slack-incoming-webhook' in registry for type 'Block'.')"
You can "watch" or subscribe to these issues on GitHub to get updates when they're resolved.Ben T
08/07/2025, 4:56 AMMarvin
08/07/2025, 4:56 AMMarvin
08/07/2025, 4:57 AMpython
# These can coexist because they're different types
from prefect.blocks.notifications import SlackWebhook
from prefect_slack import SlackWebhook # Different implementation
# Both can use the same name
slack1 = SlackWebhook(url="...")
slack1.save("my-notifications") # Type: slack-webhook
slack2 = SlackWebhook(url="...")
slack2.save("my-notifications") # Type: slack-incoming-webhook
# When loading, you specify both type and name
from prefect.blocks.core import Block
# These load different blocks despite same name
block1 = Block.load("slack-webhook/my-notifications")
block2 = Block.load("slack-incoming-webhook/my-notifications")
This is actually useful in your case because you can:
1. Keep your existing slack-notifications
block of type Slack Incoming Webhook
2. Create a new block with the same name but of type Slack Webhook
for automations
3. Use them for different purposes while maintaining similar naming
Would you like me to show you how to set this up with your existing block name?