How to run multiple processes in Docker?

2 years ago
Noah Thompson
2 minutes

In Docker, a container by default can only run one process. However, there are some tricks to make a container run multiple processes.

Here are some methods:

  1. Use process management tools like supervisord or runit: these tools can start and manage multiple processes within a container. You can install and configure these tools in your Dockerfile, and then use them to start the necessary processes.
  2. For example, using supervisord:
  3. # Dockerfile

    # Install supervisord
    RUN apt-get install -y supervisor

    # Copy supervisord configuration file
    COPY supervisord.conf /etc/supervisor/conf.d/supervisord.conf

    # Start supervisord
    CMD [“/usr/bin/supervisord”]

  4. Then configure the processes that need to be started in the supervisord.conf file.
  5. With the use of the entrypoint.sh script, you can define multiple processes to start in a Dockerfile. This script will serve as the entry point for the container, allowing processes to run in the background using the “&” symbol in the script.
  6. For example:
  7. # Dockerfile

    COPY entrypoint.sh /entrypoint.sh

    # Make entrypoint.sh executable
    RUN chmod +x /entrypoint.sh

    # Define entrypoint script as the entry point of the container
    ENTRYPOINT [“/entrypoint.sh”]

  8. Start the necessary processes in the entrypoint.sh script.
  9. #!/bin/bash

    # Start process 1
    process1 &

    # Start process 2
    process2 &

    # Wait for processes to finish
    wait

Among these methods, using a process management tool may offer more flexibility and convenience, but also requires more configuration and management. On the other hand, using the entrypoint.sh script is relatively simple, but requires manual management of each process. Choose the method that best suits your needs.

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