Yes, you can programmatically set both the API URL and API key in Prefect 3.x using the

PrefectClient

class. Here's how to do it:

python
from prefect.client.orchestration import PrefectClient

# Create a new client with custom settings
client = PrefectClient(
    api_key="your-api-key",  # Optional: Prefect Cloud API key
    api="<http://your-api-url>"  # Optional: API URL for your Prefect server
)

A few important points: 1. The client is designed to be immutable - instead of modifying an existing client, you create a new one with the desired settings. 2. If you don't specify parameters, the client will use values from your Prefect settings: - API URL defaults to what's in your

PREFECT_API_URL

setting - API key defaults to what's in your

PREFECT_API_KEY

setting 3. You can also modify these settings using environment variables:

python
   import os
   
   os.environ["PREFECT_API_URL"] = "<http://your-api-url>"
   os.environ["PREFECT_API_KEY"] = "your-api-key"
   
   # Any new client created after this will use these settings by default
   client = PrefectClient()

4. For Prefect Server (self-hosted), you typically only need to set the API URL. For Prefect Cloud, you'll need both the API URL and an API key. This approach gives you flexibility to work with multiple Prefect instances or switch between them programmatically. Each

PrefectClient

instance maintains its own configuration, so you can have multiple clients with different settings active simultaneously if needed. Remember that changes to the client configuration only affect new client instances - existing clients will maintain their original configuration until they are recreated.

To use your custom client with the Flow operations, you'll need to use the

client_injector

context manager. Here's how to modify your code:

python
from prefect.client.orchestration import PrefectClient
from prefect.client.utilities import client_injector

# Create your custom client
custom_client = PrefectClient(
    api_key="your-api-key",
    api="<http://your-api-url>"
)

# Use the client_injector context manager
async with client_injector(custom_client):
    flow = await Flow.afrom_source(
        source=gitlab_repo,
        entrypoint=deployment_entry.entrypoint,
    )

    await flow.deploy(
        **deployment_dict,
        version=new_hash,
    )

The

client_injector

context manager ensures that your custom client is used for all Prefect operations within its scope. This includes both the

Flow.afrom_source()

and

flow.deploy()

operations. A few important points: 1. The context manager must be used in an async context (with

async with

) 2. All operations that need to use the custom client should be within the context manager's scope 3. Once you exit the context manager, Prefect will revert to using the default client configuration This approach allows you to temporarily override the default client settings for specific operations while maintaining the ability to use different client configurations in different parts of your code.

For the synchronous

serve

operation, you'll need to use a synchronous client instead. Here's how to modify your code:

python
from prefect.client.orchestration import get_client

# Create a synchronous client
custom_client = get_client(
    api_key="your-api-key",
    api="<http://your-api-url>",
    sync_client=True  # This is important - it creates a synchronous client
)

# Set the client before the serve operation
with custom_client:
    klass.flow_method.serve(
        name=deployment_name,
        paused=klass.paused,
        triggers=klass.triggers,
        parameters=klass.parameters,
        description=klass.description,
        tags=klass.tags,
        version=klass.version,
    )

Key points: 1. Use

get_client()

with

sync_client=True

instead of

PrefectClient

directly 2. The synchronous client can be used with a regular

with

statement (not

async with

) 3. The client context manager will ensure all operations within its scope use your custom client configuration If you need to mix both async and sync operations, you can create both types of clients:

python
from prefect.client.orchestration import PrefectClient, get_client

# For async operations
async_client = PrefectClient(
    api_key="your-api-key",
    api="<http://your-api-url>"
)

# For sync operations
sync_client = get_client(
    api_key="your-api-key",
    api="<http://your-api-url>",
    sync_client=True
)

# Use async client for async operations
async with client_injector(async_client):
    # Your async operations here
    pass

# Use sync client for sync operations
with sync_client:
    klass.flow_method.serve(
        name=deployment_name,
        paused=klass.paused,
        triggers=klass.triggers,
        parameters=klass.parameters,
        description=klass.description,
        tags=klass.tags,
        version=klass.version,
    )

This approach gives you the flexibility to handle both synchronous and asynchronous operations while maintaining custom client settings for both contexts.

The behavior you're observing is actually expected. WebSocket connections in Prefect handle authentication differently from HTTP requests. Instead of using the

Authorization

header, WebSocket connections in Prefect typically authenticate using query parameters in the WebSocket URL. Here's why and how to handle it: 1. HTTP Requests: These use the standard

Authorization: Bearer <token>

header format, which you're correctly seeing. 2. WebSocket Connections: These authenticate using a token query parameter in the WebSocket URL. The authentication token should be automatically included in the WebSocket connection URL when you properly configure your API key. To ensure proper authentication for WebSocket connections: 1. Make sure you've set your API key correctly:

bash
   export PREFECT_API_KEY="your-api-key"

2. If you're creating a custom client, ensure you pass the API key:

python
   from prefect.client import get_client
   
   client = get_client(api_key="your-api-key")

3. If you're running a self-hosted server, verify your authentication settings in your server configuration. If you're still not seeing proper authentication after these steps, you might want to: 1. Verify your API key is being properly recognized by running a simple authenticated HTTP request 2. Check your server logs for any authentication-related errors 3. Ensure you're not behind a proxy that might be stripping authentication parameters For more details on Prefect security settings and authentication, you can refer to the security settings documentation.