Skip to main content
In this lesson, we’ll walk through how to leverage GitLab CI/CD reference tags (!reference) and standard YAML anchors to share configuration snippets across multiple jobs. By doing so, you can DRY up your pipeline definitions—pulling in values like image, before_script, or script from one job into another and avoiding duplication.

​
1. Basic YAML Anchors and !reference Tags

GitLab CI/CD supports two primary mechanisms for reusing snippets:
MethodSyntaxUse Case
YAML Anchors&anchor / *aliasShare simple lists or maps within the file
GitLab !reference!reference [job, section]Import complete sections (script, etc.)
# .gitlab-ci.yml
.default_scripts: &default_scripts
  - ./default-script1.sh
  - ./default-script2.sh

job1:
  script:
    - *default_scripts
Or use GitLab’s custom reference tag: 
# setup.yml
.setup:
  script:
    - echo "creating environment"

# .gitlab-ci.yml
include:
  - local: setup.yml

.teardown:
  after_script:
    - echo "deleting environment"

test:
  script:
    - !reference [.setup, script]
YAML anchors work within the same file, while !reference can pull from hidden jobs or included files.

​
2. Preparing the Kubernetes Environment

Let’s define two hidden jobs: one for Node.js and one for Kubernetes deployment. We’ll attach an anchor (&kubernetes_deploy_job) to reuse the Kubernetes job’s image later. 
variables:
  # Add global variables here…

.prepare_nodejs_environment:
  image: node:14
  script:
    - npm install

.prepare_deployment_environment: &kubernetes_deploy_job
  image:
    name: alpine:3.7
  dependencies: []
  before_script:
    - wget https://storage.googleapis.com/kubernetes-release/release/$(wget -q -O - https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/linux/amd64/kubectl
    - chmod +x ./kubectl
    - mv ./kubectl /usr/bin/kubectl
    - apk add --no-cache gettext
    - envsubst --version
Make sure hidden jobs (prefixed with .) are not executed on their own—they only serve as references.

​
3. Two Almost-Identical Integration Tests

Consider two integration testing jobs—dev and staging. They share the same image, identical before_script, and script blocks: 
k8s_dev_deploy:
  stage: dev-deploy
  image: alpine:3.7
  needs:
    - k8s_stage_deploy
  before_script:
    - apk --no-cache add curl jq
  script:
    - echo "$INGRESS_URL"
    - curl -s -k "https://$INGRESS_URL/live"  | jq -r .status | grep -i live
    - curl -s -k "https://$INGRESS_URL/ready" | jq -r .status | grep -i ready

k8s_stage_deploy:
  stage: stage-deploy
  image: alpine:3.7
  needs:
    - k8s_dev_deploy
  before_script:
    - apk --no-cache add curl jq
  script:
    - echo "$INGRESS_URL"
    - curl -s -k "https://$INGRESS_URL/live"  | jq -r .status | grep -i live
    - curl -s -k "https://$INGRESS_URL/ready" | jq -r .status | grep -i ready
Rather than duplicating, let’s pull these blocks into new jobs via !reference.

​
4. Reusing the image Definition

We can reuse the image from .prepare_deployment_environment with: 
k8s_dev_integration_testing:
  stage: dev-deploy
  image: !reference [.prepare_deployment_environment, image]
  needs:
    - k8s_dev_deploy
  before_script:
    - apk --no-cache add curl jq
  script:
    - echo "$INGRESS_URL"
    - curl -s -k "https://$INGRESS_URL/live"  | jq -r .status | grep -i live
    - curl -s -k "https://$INGRESS_URL/ready" | jq -r .status | grep -i ready

k8s_stage_integration_testing:
  stage: stage-deploy
  image: !reference [.prepare_deployment_environment, image]
  needs:
    - k8s_stage_deploy
  before_script:
    - apk --no-cache add curl jq
  script:
    - echo "$INGRESS_URL"
    - curl -s -k "https://$INGRESS_URL/live"  | jq -r .status | grep -i live
    - curl -s -k "https://$INGRESS_URL/ready" | jq -r .status | grep -i ready
Now, updating the base image in one place updates both jobs.

​
5. Reusing before_script and script Blocks

To avoid repeating before_script or script, reference the dev-integration job directly: 
k8s_dev_integration_testing:
  stage: dev-deploy
  image: !reference [.prepare_deployment_environment, image]
  needs:
    - k8s_dev_deploy
  before_script:
    - apk --no-cache add curl jq
  script:
    - echo "$INGRESS_URL"
    - curl -s -k "https://$INGRESS_URL/live"  | jq -r .status | grep -i live
    - curl -s -k "https://$INGRESS_URL/ready" | jq -r .status | grep -i ready

k8s_stage_integration_testing:
  stage: stage-deploy
  image: !reference [.prepare_deployment_environment, image]
  needs:
    - k8s_stage_deploy
  before_script: !reference [k8s_dev_integration_testing, before_script]
  script:        !reference [k8s_dev_integration_testing, script]
This ensures both jobs stay in sync for setup and testing steps.

​
6. Full Snippet with Artifacts and Environment

For a consolidated pipeline, include artifacts and environment details alongside your reused blocks: 
artifacts:
  reports:
    dotenv:
      - app_ingress_url.env

environment:
  name: staging
  url: "https://$INGRESS_URL"

k8s_stage_integration_testing:
  stage: stage-deploy
  image: !reference [.prepare_deployment_environment, image]
  needs:
    - k8s_stage_deploy
  before_script: !reference [k8s_dev_integration_testing, before_script]
  script:        !reference [k8s_dev_integration_testing, script]

​
Conclusion

By combining standard YAML anchors (& / *) with GitLab’s custom !reference tags, you can effectively DRY up your CI/CD definitions. Pull in common image, before_script, or script sections from hidden or existing jobs—simplifying maintenance and reducing errors.

Watch Video