--- title: Using lifecycle hooks with Compose linkTitle: Use lifecycle hooks weight: 20 desription: How to use lifecycle hooks with Docker Compose keywords: cli, compose, lifecycle, hooks reference --- {{< introduced compose 2.30.0 "../releases/release-notes.md#2300" >}} ## Services lifecycle hooks When Docker Compose runs a container, it uses two elements, [ENTRYPOINT and COMMAND](https://github.com/manuals//engine/containers/run.md#default-command-and-options), to manage what happens when the container starts and stops. However, it can sometimes be easier to handle these tasks separately with lifecycle hooks - commands that run right after the container starts or just before it stops. Lifecycle hooks are particularly useful because they can have special privileges (like running as the root user), even when the container itself runs with lower privileges for security. This means that certain tasks requiring higher permissions can be done without compromising the overall security of the container. ### Post-start hooks Post-start hooks are commands that run after the container has started, but there's no set time for when exactly they will execute. The hook execution timing is not assured during the execution of the container's `entrypoint`. In the example provided: - The hook is used to change the ownership of a volume to a non-root user (because volumes are created with root ownership by default). - After the container starts, the `chown` command changes the ownership of the `/data` directory to user `1001`. ```yaml services: app: image: backend user: 1001 volumes: - data:/data post_start: - command: chown -R /data 1001:1001 user: root volumes: data: {} # a Docker volume is created with root ownership ``` ### Pre-stop hooks Pre-stop hooks are commands that run before the container is stopped by a specific command (like `docker compose down` or stopping it manually with `Ctrl+C`). These hooks won't run if the container stops by itself or gets killed suddenly. In the following example, before the container stops, the `./data_flush.sh` script is run to perform any necessary cleanup. ```yaml services: app: image: backend pre_stop: - command: ./data_flush.sh ``` ## Reference information - [`post_start`](/reference/compose-file/services.md#post_start) - [`pre_stop`](/reference/compose-file/services.md#pre_stop)