[开发工具]gitlab ci Anchors介绍与实践

gitlab-ci.yml有个方便的功能称为Anchors 中文是"锚"的意思,它可以让你轻松的在文档中复制内容。Anchors可用于复制/继承属性，并且是使用hidden keys来提供模版的完美示例。

下面这个例子使用了anchors和map merging。它将会创建两个jobs，test1和test2，该jobs将集成.job_template的参数，每个job都自定义脚本：

案例一：

.job_template: &job_definition  # Hidden key that defines an anchor named 'job_definition'
  image: ruby:2.1
  services:
    - postgres
    - redis

test1:
  <<: *job_definition           # Merge the contents of the 'job_definition' alias
  script:
    - test1 project

test2:
  <<: *job_definition           # Merge the contents of the 'job_definition' alias
  script:
    - test2 project

&在anchor的名称(job_definition)前设置，<<表示"merge the given hash into the current one"，*包括命名的anchor(job_definition)。扩展版本如下：

.job_template:
  image: ruby:2.1
  services:
    - postgres
    - redis

test1:
  image: ruby:2.1
  services:
    - postgres
    - redis
  script:
    - test1 project

test2:
  image: ruby:2.1
  services:
    - postgres
    - redis
  script:
    - test2 project

案例二：

.build_base: &build_base
  stage: build
  image: monachus/hugo
  artifacts:
    paths:
      - public
  script:
  - export
  - hugo --baseURL ${BASE_URL}

build:production:
  <<: *build_base
  variables:
    <<: *production_variables
    GIT_SUBMODULE_STRATEGY: recursive
  only:
   - master
   
   
build:staging:
  <<: *build_base
  variables:
    <<: *staging_variables
    GIT_SUBMODULE_STRATEGY: recursive
  only:
   - dev

.deploy_base: &deploy_base
  stage: deploy
  image: monachus/hugo
  script:
    - hugo --baseURL ${BASE_URL}

deploy:production:
  <<: *deploy_base
  variables:
    <<: *production_variables
  dependencies:
   - build:production
  only:
   - master

deploy:staging:
  <<: *deploy_base
  variables:
    <<: *staging_variables
  dependencies:
   - build:staging
  only:
   - dev

案例三：

使用anchors来定义两个服务。两个服务会创建两个job，test:postgres和test:mysql，他们会在.job_template中共享定义的script指令，以及分别在.postgres_services和.mysql_services中定义的service指令：

.job_template: &job_definition
  script:
    - test project

.postgres_services:
  services: &postgres_definition
    - postgres
    - ruby

.mysql_services:
  services: &mysql_definition
    - mysql
    - ruby

test:postgres:
  <<: *job_definition
  services: *postgres_definition

test:mysql:
  <<: *job_definition
  services: *mysql_definition

扩展版本如下：

.job_template:
  script:
    - test project

.postgres_services:
  services:
    - postgres
    - ruby

.mysql_services:
  services:
    - mysql
    - ruby

test:postgres:
  script:
    - test project
  services:
    - postgres
    - ruby

test:mysql:
  script:
    - test project
  services:
    - mysql
    - ruby

可以看到hidden keys被方便的用作模版。