GitLab Runner: Speeding up repeat builds

This documentation is part of the Building Docker images guide. You can view the complete guide here: Build and push Docker images efficiently from your GitLab CI/CD pipelines using Stackhero runners and Docker-in-Docker.

👋 Welcome to the Stackhero documentation!

Stackhero offers a simple GitLab Runner cloud solution that makes running your GitLab CI/CD jobs efficient and straightforward. Here’s what you can expect:

• Unlimited CI/CD minutes: run your pipelines as often as you need, with no per-minute billing or unexpected fees.
• Multiple concurrent jobs: speed up your development by running several jobs in parallel.
• The Docker executor with Docker-in-Docker support: easily build and push container images as part of your CI/CD workflows.
• Works seamlessly with both GitLab.com and self-managed GitLab instances.
• A private, dedicated infrastructure with fast NVMe/SSD storage ensures stable and predictable build performance.
• Available in 🇪🇺 Europe and 🇺🇸 USA regions to meet your team's needs.

Save time: you can connect your first GitLab Runner and start running pipelines in just a few minutes!

Your runner's disk persists between pipelines, allowing you to reuse image layers as a build cache. This can make repeated builds much faster. Here is an example configuration:

build-cached:
  stage: build
  image: docker:29
  services:
    - name: docker:29-dind
      alias: docker
  variables:
    DOCKER_HOST: "tcp://docker:2375"
    DOCKER_TLS_CERTDIR: ""
  before_script:
    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" "$CI_REGISTRY"
  script:
    # Pull the latest image to seed the cache (if it exists):
    - docker pull "$CI_REGISTRY_IMAGE:latest" || true
    - docker build --cache-from "$CI_REGISTRY_IMAGE:latest" -t "$CI_REGISTRY_IMAGE:latest" .
    - docker push "$CI_REGISTRY_IMAGE:latest"

This approach allows your builds to leverage Docker's layer caching, so only new or changed layers are rebuilt.