updater-docker

Updates a version argument in a Dockerfile.

This plugin is distributed as the standalone Go binary semrel-plugin-updater-docker. Semrel executes the binary as a subprocess, provides plugin configuration through SEMREL_PLUGIN_* environment variables, provides release context through SEMREL_* environment variables, reads standard output, and treats exit code 0 as success and any non-zero exit code as failure. Install the binary in ~/.semrel/plugins/ or anywhere on your $PATH.

Installation

Binary

go install github.com/SemRels/updater-docker/cmd/plugin@latest

Docker

Pre-built, multi-platform images (linux/amd64, linux/arm64) are published to the GitHub Container Registry on every release:

docker pull ghcr.io/semrels/updater-docker:latest

Images are signed with cosign and include a full SBOM attestation. Verify the signature:

cosign verify ghcr.io/semrels/updater-docker:latest \
  --certificate-identity-regexp 'https://github.com/SemRels/updater-docker/.github/workflows/release.yml.*' \
  --certificate-oidc-issuer https://token.actions.githubusercontent.com

Configuration

plugins:
  - name: updater-docker
    path: ~/.semrel/plugins/semrel-plugin-updater-docker
    env:
      SEMREL_PLUGIN_FILE: "Dockerfile"
      SEMREL_PLUGIN_ARG_NAME: "VERSION"

SEMREL_PLUGIN_* variables

Name	Required	Description	Default
SEMREL_PLUGIN_FILE	Optional	Path to the Dockerfile to update.	Dockerfile
SEMREL_PLUGIN_ARG_NAME	Optional	Docker build argument name that stores the version.	VERSION

SEMREL_* release context used

Variable	Description
SEMREL_VERSION	Resolved release version for the current run.
SEMREL_NEXT_VERSION	Next version computed by semrel for the release.
SEMREL_DRY_RUN	Whether semrel is running in dry-run mode.

Example behavior

The plugin updates the configured Docker build argument to the new release version and prints what changed.

License

Apache-2.0