Based on your description, I can identify a few potential issues. Here's how to resolve this: 1. API URL Configuration The temporary server works because it's running locally, but to connect to your containerized server, you need to set the correct API URL. Add this to the top of your script:

python
   from prefect.settings import set_setting
   set_setting("PREFECT_API_URL", "<http://localhost:4200/api>")

Alternatively, you can set it as an environment variable:

bash
   export PREFECT_API_URL="<http://localhost:4200/api>"

2. Container Network Make sure your container is properly exposing both: - Port 4200 for the UI (which you've confirmed is working) - Port 4200 for the API 3. Verify Server Status You can verify the server is properly running and accessible by:

bash
   curl <http://localhost:4200/api/health>

This should return a successful response if the API is accessible. 4. Common Gotchas - Ensure you're not using any Prefect Cloud settings (like

PREFECT_API_KEY

) - If you're running the script from inside another container, you'll need to use the container network address instead of

localhost

- The

/api

suffix in the URL is important - don't omit it If you're still having issues, could you share: 1. The specific error message you're seeing? 2. How you started the Prefect server in podman? 3. Whether you're running your Python script from inside another container or from your host machine? This will help me provide more targeted assistance.

This is actually a common container networking behavior, not a terminal-specific issue. Here's what's happening: 1. The fact that

127.0.0.1

works consistently while

localhost

is intermittent suggests that the server inside the container might not be binding to all available interfaces. Here's how to fix this: 1. Stop your current Prefect server container 2. Start the server with explicit host binding:

bash
   podman run -p 4200:4200 prefecthq/prefect:2-latest prefect server start --host 0.0.0.0

The

--host 0.0.0.0

flag is crucial here - it tells the server to bind to all available network interfaces. 3. Configure your client:

python
   from prefect.settings import set_setting
   set_setting("PREFECT_API_URL", "<http://127.0.0.1:4200/api>")

4. Verify the connection:

bash
   curl <http://127.0.0.1:4200/api/health>

This should now consistently return

true

. The reason for this behavior: -

localhost

can sometimes resolve differently in containerized environments -

0.0.0.0

means "bind to all interfaces" (good for the server) -

127.0.0.1

is the explicit loopback address (more reliable for client connections) If you're still seeing intermittent issues after making these changes, there might be additional networking configurations in your podman setup that need attention. Let me know if you need help with that.

Your command looks mostly correct, but there are a few considerations: 1. Image Tag: You're using

prefecthq/prefect:3-python3.13

which is quite specific. While this works, Python 3.13 is still in alpha. Unless you specifically need 3.13 features, you might want to use a more stable version like:

bash
   prefecthq/prefect:3-python3.11

2. Container Management Flags: -

-d

(detached mode) ✅ Good -

--rm

(remove container when stopped) ✅ Good for development - You might want to consider adding: -

--name prefect-server

(makes it easier to manage) -

-v prefect-data:/root/.prefect

(persist data between restarts) Here's a more complete command that includes these suggestions:

bash
podman run \
  -d \
  --rm \
  --name prefect-server \
  -v prefect-data:/root/.prefect \
  -p 4200:4200 \
  prefecthq/prefect:3-python3.11 \
  prefect server start --host 0.0.0.0

For your client code, make sure you're using:

python
from prefect.settings import set_setting
set_setting("PREFECT_API_URL", "<http://127.0.0.1:4200/api>")

Since you mentioned the web UI is accessible but the API connection is failing, let's verify a few things: 1. Check the server logs:

bash
podman logs prefect-server

Look for any error messages or warnings about the API binding. 2. Try these curl commands and let me know which ones work:

bash
curl <http://127.0.0.1:4200/api/health>
curl <http://0.0.0.0:4200/api/health>
curl <http://localhost:4200/api/health>

3. Check if the port is properly bound:

bash
podman port prefect-server

This should help us narrow down whether it's a container networking issue or a client configuration issue.

✅ thought for 31.5 seconds

You're absolutely right on both counts, and I apologize for the incorrect information earlier! Let me summarize the key learnings: 1. Correct API URL Configuration:

bash
   export PREFECT_API_URL="<http://127.0.0.1:4200/api>"

2. Address Requirements: - ✅ Use

127.0.0.1

or

0.0.0.0

- ❌ Avoid

localhost

as it can be unreliable in containerized environments 3. Settings Configuration: You're correct that my previous suggestion about

set_setting

was incorrect for Prefect 3.x. The environment variable approach is the recommended way to configure the API URL. This is a great example of how container networking can be particular about how we reference addresses, and it's valuable to know that

localhost

isn't always a reliable option in these scenarios. Would you like me to explain more about why

localhost

behaves differently from

127.0.0.1

in this context, or would you prefer information about other environment variables that might be useful for your Prefect setup?

You're absolutely right on both counts! Let me correct the record: 1. Network Binding: - ✅

127.0.0.1

works - ✅

0.0.0.0

works - ❌

localhost

is unreliable in containerized environments 2. Configuration Method: I apologize for the incorrect code example. In Prefect 3.x, there are several ways to set the API URL: a. Environment variable (as you discovered):

bash
export PREFECT_API_URL="<http://127.0.0.1:4200/api>"

b. Using the Prefect CLI:

bash
prefect config set PREFECT_API_URL="<http://127.0.0.1:4200/api>"

c. Via a

.env

file in your project directory:

PREFECT_API_URL="<http://127.0.0.1:4200/api>"

The

set_setting

import I provided was indeed incorrect for Prefect 3.x - thank you for catching that. The environment variable approach you're using is the most straightforward and reliable method. Would you like me to store this information about your environment setup for future reference?

You're absolutely right about helping future users. Let me summarize the key learning for anyone following the quickstart tutorial with a self-hosted server: Important Tutorial Prerequisite When running the Prefect server in a container, you must set the API URL before running your flows:

bash
export PREFECT_API_URL="<http://127.0.0.1:4200/api>"

Key Points to Remember: 1. This step is required but not explicitly mentioned in the quickstart 2. Use

127.0.0.1

or

0.0.0.0

, not

localhost

3. Don't forget the

/api

suffix 4. The environment variable must be set in the environment where you're running your flows Without this configuration, flows will try to use a temporary server instead of connecting to your containerized server, even though the UI might be accessible in your browser. This is particularly important for users following the tutorial in a self-hosted environment, as it bridges a potential gap between the basic quickstart and a more production-like setup.