Stamp every build with its version

How to do it

Pass the version and commit hash into the build, for example as build arguments or a generated file. Never type them by hand. Return them from a version address or the health check, and add them to every log line and error report. Tag the commit of every production release, such as v2026.10.20-1 or a semantic version for a library. Send the version to the dashboards as a deploy marker.

Example

docker build --build-arg VERSION="$(git describe --tags --always)" --build-arg COMMIT="$(git rev-parse HEAD)" .

// The Dockerfile turns the build arguments into environment variables
app.get('/version', (req, res) => {
  res.json({ version: process.env.VERSION, commit: process.env.COMMIT });
});

# Flask
@app.get("/version")
def version():
    return {"version": os.environ["VERSION"], "commit": os.environ["COMMIT"]}

// Set at build time: go build -ldflags "-X main.commit=$(git rev-parse HEAD)"
var commit = "unknown"

http.HandleFunc("/version", func(w http.ResponseWriter, r *http.Request) {
	json.NewEncoder(w).Encode(map[string]string{"commit": commit})
})

How to check

After a deploy, the version address returns the commit hash of the deployed commit. git tag --points-at <that commit> prints the release tag.