GitLab Runner: Speeding up repeat builds

This documentation is part of the Building Docker images guide. View the full guide here: Build and push Docker images from your GitLab CI/CD pipelines using your Stackhero runner and Docker-in-Docker.

👋 Welcome to the Stackhero documentation!

Stackhero gives you an easy-to-use GitLab Runner cloud solution designed to handle your GitLab CI/CD jobs efficiently. Here is what you can look forward to:

• Unlimited CI/CD minutes: there is no per-minute billing, so your pipelines can run whenever you need them.
• Multiple concurrent jobs: run several jobs at the same time to speed up your entire pipeline.
• The Docker executor with Docker-in-Docker support: streamline building and pushing your container images.
• Compatible with GitLab.com as well as any self-managed GitLab instance.
• A private, dedicated VM powered by fast NVMe/SSD disks for consistent, reliable builds.
• Available in both 🇪🇺 Europe and 🇺🇸 USA regions.

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

Since your runner's disk persists between pipelines, you can speed up builds by reusing previous image layers as a cache. Here is how you can set that up:

build-cached:
  stage: build
  image: docker:27
  services:
    - docker:27-dind
  variables:
    DOCKER_TLS_CERTDIR: "/certs"
  before_script:
    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" "$CI_REGISTRY"
  script:
    # Try pulling the latest image to seed the cache (it is okay if it does not exist yet):
    - docker pull "$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 helps your pipelines finish faster over time by making the most of Docker's layer caching.