For a self-hosted Prefect server using basic authentication, you'll need to configure both the server and client sides. Here's how: 1. Server Configuration: When starting your Prefect server, set the auth string:

bash
prefect server start --host 0.0.0.0 --port 4200 --server.api.auth_string="admin:password"

2. Client Configuration: For client processes that need to communicate with the server, set these environment variables:

bash
export PREFECT_API_URL="<http://my-prefect.com/api>"
export PREFECT_API_AUTH_STRING="admin:password"

Alternatively, you can configure this in your Python code:

python
from prefect.settings import Setting
from prefect.client.schemas.actions import AuthType

Setting(name="PREFECT_API_URL", value="<http://my-prefect.com/api>").save()
Setting(name="PREFECT_API_AUTH_STRING", value="admin:password").save()

Important notes: - Replace "admin:password" with your actual credentials - Do NOT set

PREFECT_API_KEY

when using basic auth - this will cause authentication errors - The auth string format is always

username:password

- Make sure to use the same credentials on both server and client sides You can verify your authentication is working by accessing your server's API documentation at

<http://my-prefect.com/docs>

and using the "Authorize" button with your credentials. For additional security settings and configurations, you can refer to the security settings documentation.

I'll help you modify this code to work with basic authentication for a self-hosted Prefect server. Here's the corrected version:

python
import base64
import requests

def trigger_prefect_flow():
    # Basic auth credentials
    username = "admin"
    password = "password"
    
    # Create basic auth header
    credentials = f"{username}:{password}"
    encoded_credentials = base64.b64encode(credentials.encode('utf-8')).decode('utf-8')
    
    url = f"{PREFECT_API_URL}/deployments/{PREFECT_FLOW_ID}/run"
    headers = {
        "Authorization": f"Basic {encoded_credentials}",
        "Content-Type": "application/json"
    }
    
    response = <http://requests.post|requests.post>(url, headers=headers)
    if response.ok:
        print("Prefect flow triggered successfully.")
    else:
        print(f"Failed to trigger Prefect flow. Status: {response.status_code}, Response: {response.text}")

Key changes made: - Removed the Bearer token authentication (which is for Prefect Cloud) - Added basic auth using base64 encoding (this is how HTTP Basic Auth works) - The credentials are encoded as

base64(username:password)

Alternatively, you can use requests' built-in basic auth support, which is even cleaner:

python
import requests

def trigger_prefect_flow():
    username = "admin"
    password = "password"
    
    url = f"{PREFECT_API_URL}/deployments/{PREFECT_FLOW_ID}/run"
    headers = {
        "Content-Type": "application/json"
    }
    
    response = <http://requests.post|requests.post>(
        url,
        headers=headers,
        auth=(username, password)
    )
    
    if response.ok:
        print("Prefect flow triggered successfully.")
    else:
        print(f"Failed to trigger Prefect flow. Status: {response.status_code}, Response: {response.text}")

Both approaches will work the same way - the second version is preferred as it lets the requests library handle the auth header construction for you. Just remember to replace "admin" and "password" with your actual credentials. Also, make sure your

PREFECT_API_URL

and

PREFECT_FLOW_ID

variables are properly defined before running this code.

The correct API path for triggering a deployment's flow run is:

POST /api/deployments/{deployment_id}/create_flow_run

So your code should be updated to:

python
import requests

def trigger_prefect_flow(deployment_id):
    username = "admin"
    password = "password"
    
    url = f"{PREFECT_API_URL}/api/deployments/{deployment_id}/create_flow_run"
    headers = {
        "Content-Type": "application/json"
    }
    
    response = <http://requests.post|requests.post>(
        url,
        headers=headers,
        auth=(username, password)
    )
    
    if response.ok:
        print("Prefect flow triggered successfully.")
        return response.json()
    else:
        print(f"Failed to trigger Prefect flow. Status: {response.status_code}, Response: {response.text}")
        return None

Note the key differences: - The path is

/api/deployments/{deployment_id}/create_flow_run

(not

/deployments/{id}/run

) - The endpoint returns JSON with details about the created flow run You can also optionally include parameters and tags in the request body:

python
    # Optional: include parameters or tags
    data = {
        "parameters": {"key": "value"},
        "tags": ["tag1", "tag2"]
    }
    response = <http://requests.post|requests.post>(
        url,
        headers=headers,
        auth=(username, password),
        json=data
    )

The full API documentation for this endpoint can be found at: https://docs-3.prefect.io/v3/api-ref/rest-api/server/deployments/create-flow-run-from-deployment

A 405 Method Not Allowed error typically means we're either: 1. Using the wrong HTTP method, or 2. Using an incorrect endpoint path Let me verify the exact endpoint structure. There are actually two ways to trigger a flow run: 1. Using the deployments endpoint:

python
url = f"{PREFECT_API_URL}/api/deployments/{deployment_id}/create_flow_run"

2. Using the flow runs endpoint:

python
url = f"{PREFECT_API_URL}/api/flow_runs/create_deployment_flow_run"

Here's the corrected code using the second approach, which might be more reliable:

python
import requests

def trigger_prefect_flow(deployment_id):
    username = "admin"
    password = "password"
    
    url = f"{PREFECT_API_URL}/api/flow_runs/create_deployment_flow_run"
    headers = {
        "Content-Type": "application/json"
    }
    
    # Include the deployment_id in the request body
    data = {
        "deployment_id": deployment_id
    }
    
    response = <http://requests.post|requests.post>(
        url,
        headers=headers,
        auth=(username, password),
        json=data
    )
    
    if response.ok:
        print("Prefect flow triggered successfully.")
        return response.json()
    else:
        print(f"Failed to trigger Prefect flow. Status: {response.status_code}, Response: {response.text}")
        return None

Also, please verify: 1. Your

PREFECT_API_URL

doesn't have a trailing slash 2. The deployment ID exists and is valid 3. You can access other API endpoints successfully If you're still getting a 405 error, could you share: 1. The exact URL you're trying to hit (with sensitive info redacted) 2. Whether you can access the Prefect UI and see the deployment there 3. Whether you can trigger the deployment from the UI successfully This will help narrow down if it's an authentication, URL structure, or API endpoint issue.