Nicolas De LoofandClaude Fable 5
725fe535c0
ServiceHash digests json.Marshal of types.ServiceConfig, which couples every recorded config-hash to the DECLARATION ORDER of compose-go struct fields: encoding/json emits struct fields in that order and flattens embedded structs at their embedding position. Any compose-go refactoring that moves a field — such as the upcoming container-spec layering, which regroups the whole struct — would change the bytes, and with them the hash, of configurations that did not change at all: every container recreated on the first `up` after an upgrade. The hash now re-emits the marshaled object with its ROOT keys in a frozen list reproducing the historical order (generated by reflection over the last pre-layering compose-go), values byte-verbatim. For today, the output is byte-identical to the direct marshal — proven by a continuity test — so every existing container stamp stays valid: no migration, no recreation, full backward compatibility. From the first struct reorder on, the frozen list alone carries that continuity, locked by golden-value tests; a root attribute added later is appended in sorted order and, thanks to omitempty, only moves the hash of configurations that use it — exactly like a field addition always did. A reflection test fails when compose-go grows a root attribute missing from the list, so extending the hash surface stays a reviewed decision. Nested objects keep their own struct marshal: a reorder inside one of them would still move hashes — the golden tests exist to turn that into a caught, reviewed event rather than a silent side effect. Network and volume hashes are unchanged (their structs are not being reordered) and gain the same golden locks. Co-Authored-By: Claude Fable 5 <[email protected]> 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.