Скачать или смотреть How to Fix Running Python Scripts from Shell Files in Docker

Discover the simple solution to run multiple Python scripts from a shell script in Docker. Learn how to run Gunicorn in the background for seamless execution.
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Troubleshooting Python Scripts in Docker: Running from Shell Files

When working on a Docker container that executes Python scripts, it can be frustrating when things don’t go as planned. One common obstacle developers face is running multiple scripts from a single shell script, especially when employing a web server like Gunicorn. In this guide, we will explore a scenario where you might run into issues and how to resolve them effectively.

The Problem

Imagine you have a shell script script.sh aimed at running an API and a scheduler script. Here is a snippet of your script:

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In this setup, you find that while your run_api endpoint works flawlessly, the run_scheduler.py script does not execute. This issue arises because Gunicorn, which is responsible for running your web application, occupies the foreground and prevents subsequent commands in your shell script from running.

Understanding the Issue

Why Does This Happen?

Blocking Process: When you execute gunicorn, it starts as a blocking process. This means it takes control of the terminal and the shell script cannot move on to execute the next line (which is your scheduler script).

Multi-tasking in Shell Scripts: Shell scripts can run commands in the background, allowing multiple processes to run simultaneously. However, you need to explicitly tell them to do so.

The Solution

To resolve this issue, you need to modify your script.sh to run the Gunicorn server in the background, allowing the shell to continue executing the remaining commands. Here’s how to adjust your script:

Step 1: Update Your Shell Script

Modify script.sh as follows:

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Explanation of Changes

Appending &: By adding & at the end of the Gunicorn command, you instruct the shell to run this command in the background. This allows the subsequent line to be executed without waiting for Gunicorn to finish.

Implementing in Docker

Make sure your Docker setup accommodates these changes. Here’s a brief look at your Dockerfile:

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It’s excellent that you’ve set up the permissions for script.sh and defined the CMD. Ensure to build and run your Docker container again with this updated script.

Docker Run Command

To launch your Docker container, you would use the following command:

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This command runs your modified container in detached mode, mapping port 8080 on your host to port 5000 in the container.

Conclusion

By ensuring that your web server runs in the background, you can seamlessly execute additional scripts from your shell file. This simple solution not only improves the performance of your application but also helps streamline the workflow significantly. If you encounter similar issues in the future, remember that multi-tasking in shell scripts requires a little extra setup!

With this knowledge, you should now be able to run multiple Python scripts efficiently in your Docker setups without a hitch. Happy coding!