Nicolas De Loof
fc630f7792
pre_start hooks run in ephemeral containers. When a run fails, the runner is deliberately retained for post-mortem inspection, and the next run purges it — but that purge lived entirely inside the imperative primitive, invisible to the reconciliation plan. It is now a plan operation: when pre_start is going to run again (hooks declared, no replica running at observation — the imperative gating), the plan emits one best-effort RemoveContainer per stale runner, dropping its anonymous volumes, exactly the warn-only semantics of the imperative purge that remains in place as backstop. Observed state learns to tell hook containers apart: they carry no container-number label and previously classified as a service replica numbered 0. They now land in a dedicated HookContainers bucket the reconciler plans purges from. The imperative primitive is also split into its lifecycle-free execution piece (execPreStartHook: start, wait, log streaming, retain-on-failure) and the create/remove pieces around it, recomposed identically in runPreStart — locked by the existing characterization tests. This prepares moving hook-container creation and post-success removal into the plan once the start phase lands (#14200). Signed-off-by: Nicolas De Loof <[email protected]>
Table of Contents
Docker Compose
Docker Compose is a tool for running multi-container applications on Docker
defined using the Compose file format.
A Compose file is used to define how one or more containers that make up
your application are configured.
Once you have a Compose file, you can create and start your application with a
single command: docker compose up.
Note
: About Docker Swarm Docker Swarm used to rely on the legacy compose file format but did not adopt the compose specification so is missing some of the recent enhancements in the compose syntax. After acquisition by Mirantis swarm isn't maintained by Docker Inc, and as such some Docker Compose features aren't accessible to swarm users.
Where to get Docker Compose
Windows and macOS
Docker Compose is included in Docker Desktop for Windows and macOS.
Linux
You can download Docker Compose binaries from the release page on this repository.
Rename the relevant binary for your OS to docker-compose and copy it to $HOME/.docker/cli-plugins
Or copy it into one of these folders to install it system-wide:
/usr/local/lib/docker/cli-pluginsOR/usr/local/libexec/docker/cli-plugins/usr/lib/docker/cli-pluginsOR/usr/libexec/docker/cli-plugins
(might require making the downloaded file executable with chmod +x)
Quick Start
Using Docker Compose is a three-step process:
- Define your app's environment with a
Dockerfileso it can be reproduced anywhere. - Define the services that make up your app in
compose.yamlso they can be run together in an isolated environment. - Lastly, run
docker compose upand Compose will start and run your entire app.
A Compose file looks like this:
services:
web:
build: .
ports:
- "5000:5000"
volumes:
- .:/code
redis:
image: redis
Contributing
Want to help develop Docker Compose? Check out our contributing documentation.
If you find an issue, please report it on the issue tracker.
Legacy
The Python version of Compose is available under the v1 branch.