Add child pipeline template for Dockerimage builds

# A child pipeline for building and tagging Docker images

#

# Usage

# -----

#

# Include this file from a trigger keyword in a job.

#

#   jobspec:

#     rules:

#       - Dockerfile

#       - entrypoint.sh

#       - src/*

#     trigger:

#       project: dom/project-templates

#       ref: main

#       file: pipeline-templates/build-image.yml

#       strategy: depend

#

# Multiple images can be built by combining with the "parallel.matrix" keyword.

# In this case the TARGET variable can be set to select both the target

# stage in the Dockerfile, as well as the output repository name.

#

#   jobspec:

#     parallel:

#       matrix:

#       - TARGET: [first-image, second-image]

#     trigger:

#       project: dom/project-templates

#       ref: main

#       file: pipeline-templates/build-image.yml

#       strategy: depend

#

#

# Variables

# ---------

#

# RELEASE:

#   Set to a release version string to tag the built images as releases

#

# TARGET:

#   The name of a stage from *Dockerfile* to produce as a build image, which

#   will also be included in the repo name of the image

#   (default: unused)

#

# PLATFORMS:

#   A comma separated list of Docker/OCI platforms to build images for

#   (default: linux/amd64, linux/arm64)

variables:

  PLATFORMS:

    value: linux/amd64,linux/arm64

    description: Docker/OCI platform specifiers for built images to target;

      comma separated

Build:

  stage: build

  image: docker.kodo.org.uk/ci-images/buildkit/buildctl:build-38

  tags: [buildkit]

  script:

  - |

    tee build.env <<ENV

    BUILD_TAG=${CI_REGISTRY_IMAGE}/build${TARGET+/$TARGET}:pipeline-${CI_PIPELINE_IID}

    ENV

    . build.env

  - |

    : buildctl build ...

    opts() { test $# -eq 0 || printf "--opt build-arg:%s" "$@"; }

    build()

    {

      opts | xargs buildctl build \

      --frontend dockerfile.v0 \

      --local context=. \

      --local dockerfile=. \

      --output type=image,push=true,name=${BUILD_TAG} \

      --opt platform="${PLATFORMS}" \

      --opt label:pipeline=${CI_PIPELINE_IID} \

      --opt label:commit=${CI_COMMIT_SHORT_SHA} \

      ${TARGET+--opt target=$TARGET}

    }

    eval "build ${BUILD_ARGS}"

  artifacts:

    reports:

      dotenv: build.env

Tag Commit:

  stage: build

  image: docker.kodo.org.uk/ci-images/docker-reg:0.2.0

  needs: [Build]

  script:

  - docker-reg ${BUILD_TAG} retag commit-${CI_COMMIT_SHORT_SHA}

Tag Release:

  stage: deploy

  image: docker.kodo.org.uk/ci-images/docker-reg:0.2.0

  needs: [Build]

  rules:

  - if: $RELEASE

    when: manual

  script:

  - docker-reg ${BUILD_TAG} retag ${CI_REGISTRY_IMAGE}${TARGET+/$TARGET}:${RELEASE}

  - docker-reg ${BUILD_TAG} retag ${CI_REGISTRY_IMAGE}${TARGET+/$TARGET}:latest