Automating common tasks can save a lot of time, increase the reliability of a system, and reduce maintenance cost. One such task to automate is to make services reload its configuration files by sending the HUP signal. So far so good. It gets more difficult to auto this with Ansible when the service runs inside a container. Here are two options.

Run kill inside container

If the image contains the kill command, you can run it inside the container. So the Ansible+Docker equivalent of kill -s HUP $PID looks as follows assuming you want to send the signal to the main process.

- name: Use kill inside the container
    container: mycontainer
    command: kill -s HUP 1

Send signal from outside

If the image does not contain the kill command, you can send a signal from outside. So the the Ansible equivalent of docker kill -s HUP $PID looks as follows.

- name: Use docker kill module
    name: mycontainer
    state: stopped    # Send signal but don't remove container
    force_kill: true  # Use kill signal instead of stop
    kill_signal: HUP  # Send HUP instead of kill

There is no need to resort to or similar.