Hi @Marvin! I have what might be a silly question: I want to start adding Prefect decorators to some existing pipelines at my org, but don't yet want everyone to need to log on to Prefect to run the pipelines when I merge those changes. Is there a Prefect-standard way to make these decorators no-ops based on some environmental state (eg. not logged into Prefect or PREFECT_API_URL not set?) I can make my own wrappers around these decorators if not but am wondering if I can save myself some work.

To make Prefect decorators like

@flow

or

@task

no-ops based on some environmental condition, such as not being logged into Prefect, you can utilize environment variables. Prefect allows you to control settings with environment variables prefixed with

PREFECT_

. Here's a possible approach: - Check if the

PREFECT_API_URL

environment variable is set. If not, you could conditionally apply Prefect decorators or bypass them altogether. While Prefect doesn't provide a built-in way to make decorators no-ops, you can define your own wrappers to conditionally apply these decorators. Here's a simple example:

python
import os
from prefect import flow, task

def conditional_flow(func):
    if os.getenv("PREFECT_API_URL"):
        return flow(func)
    return func

def conditional_task(func):
    if os.getenv("PREFECT_API_URL"):
        return task(func)
    return func

@conditional_flow
def my_flow():
    # Your flow logic here
    pass

@conditional_task
def my_task():
    # Your task logic here
    pass

This way, if

PREFECT_API_URL

is not set, the decorators will have no effect, and your functions will run as regular Python functions. For more information on environment variables in Prefect, you can refer to the Prefect Settings and Profiles documentation.

Follow-up question, @Marvin, is there a standard way to know from Python if the user's logged into Prefect Cloud via

prefect cloud login

? I'd like to use that to see if the user's logged in for these wrapper functions.

To determine if a user is logged into Prefect Cloud from Python, you can check for the presence and validity of the

PREFECT_API_URL

and

PREFECT_API_KEY

environment variables. These are typically configured when a user logs into Prefect Cloud. Here's a simple way to do this:

python
import os

def is_logged_into_prefect_cloud():
    api_url = os.getenv("PREFECT_API_URL")
    api_key = os.getenv("PREFECT_API_KEY")
    
    # Check if both API URL and API key are set and valid
    if api_url and api_key and "prefect.cloud" in api_url:
        return True
    return False

# Usage
if is_logged_into_prefect_cloud():
    print("User is logged into Prefect Cloud.")
else:
    print("User is not logged into Prefect Cloud.")

This function checks if the

PREFECT_API_URL

points to the Prefect Cloud endpoint and if the

PREFECT_API_KEY

is set, which are strong indicators that the user is logged in. For more detailed troubleshooting, refer to the Prefect Cloud Troubleshooting Guide.

@Marvin Hmm, I don't know if that's correct. Should I also check for the various .toml files? Is there a standard way to do that?

To verify if a user is logged into Prefect Cloud, you can check for specific configurations in

.toml

files along with environment variables. Prefect uses these files to store settings, including API keys and URLs. Here’s a more comprehensive approach: 1. Environment Variables: Check if

PREFECT_API_URL

and

PREFECT_API_KEY

are set and valid. This is the primary method to determine if the user is configured to access Prefect Cloud. 2. TOML Files: Prefect uses

.toml

files for configuration, which can be manually inspected or programmatically accessed. The relevant

.toml

files include: - `~/.prefect/profiles.toml`: Contains profiles, including cloud settings. -

pyproject.toml

or other project-specific TOML files: May contain Prefect settings if configured. 3. Using Prefect's API: Prefect's

settings

module provides functions to load and manage profiles, which might be stored in these TOML files. You can use functions like

load_current_profile

to programmatically access these settings. Here's an example of how you might check this programmatically:

python
from prefect.settings import load_current_profile

def is_logged_into_prefect_cloud():
    profile = load_current_profile()
    api_url = profile.settings.get("PREFECT_API_URL")
    api_key = profile.settings.get("PREFECT_API_KEY")
    
    if api_url and api_key and "prefect.cloud" in api_url:
        return True
    return False

# Usage
if is_logged_into_prefect_cloud():
    print("User is logged into Prefect Cloud.")
else:
    print("User is not logged into Prefect Cloud.")

This approach uses Prefect's internal settings management to check the current profile settings, which can include configurations from both environment variables and TOML files. For more details, you might explore the Prefect Settings Documentation.