如何在.gitlab-ci.yml中为所有before_script添加初始命令？

现有如下.gitlab-ci.yml配置：

.debug: &debug
  - echo "$CI_PROJECT_NAME"
  - echo "$CI_PIPELINE_SOURCE"
  - echo "$CI_DEFAULT_BRANCH"
  - echo "$CI_COMMIT_BRANCH"
  - pip --version || true
  - python --version || true
  - ls -al . || true
  - pwd || true
  - whoami || true

lint:
  before_script:
    - *debug
    - pip install -r requirements-lint.txt
    - <some more lint specific commands>
  script:
    - echo "lint"

build:
  before_script:
    - *debug
    - pip install -r requirements-build.txt
    - <some more build specific commands>
  script:
    - echo "build"

test:
  before_script:
    - *debug
    - pip install -r requirements-test.txt
    - <some more test specific commands>
  script:
    - echo "test"

每个任务的before_script都以*debug锚点开头，希望通过全局配置自动在所有before_script开头加入该锚点，避免重复编写。

尝试过两种方案但均存在问题：

1. 将*debug放在default:before_script中，任务仅编写script：会导致环境搭建命令与测试执行命令混在一起，不符合before_script的设计初衷。
2. 保留default:before_script: - *debug，任务单独定义自己的before_script：此时任务的before_script会直接覆盖默认配置，不会执行*debug命令。

请问是否可以实现全局为所有before_script开头添加指定命令？若可以，该如何操作？

方法1：利用GitLab CI的!reference关键字（推荐） #

GitLab CI支持通过!reference引用模板或全局配置中的特定项，实现配置合并而非覆盖。我们可以先定义包含debug命令的模板，再让每个任务的before_script先引用模板内容，再追加自己的命令：

# 定义包含debug命令的模板job
.template_debug:
  before_script:
    - echo "$CI_PROJECT_NAME"
    - echo "$CI_PIPELINE_SOURCE"
    - echo "$CI_DEFAULT_BRANCH"
    - echo "$CI_COMMIT_BRANCH"
    - pip --version || true
    - python --version || true
    - ls -al . || true
    - pwd || true
    - whoami || true

lint:
  before_script:
    # 先引用模板中的debug命令
    - !reference [.template_debug, before_script]
    - pip install -r requirements-lint.txt
    - <some more lint specific commands>
  script:
    - echo "lint"

build:
  before_script:
    - !reference [.template_debug, before_script]
    - pip install -r requirements-build.txt
    - <some more build specific commands>
  script:
    - echo "build"

test:
  before_script:
    - !reference [.template_debug, before_script]
    - pip install -r requirements-test.txt
    - <some more test specific commands>
  script:
    - echo "test"

方法2：使用YAML锚点合并语法 #

通过定义包含完整before_script结构的锚点，再让每个任务合并该锚点后扩展自己的命令：

# 定义基础before_script锚点
.base_before_script: &base_before_script
  before_script:
    - echo "$CI_PROJECT_NAME"
    - echo "$CI_PIPELINE_SOURCE"
    - echo "$CI_DEFAULT_BRANCH"
    - echo "$CI_COMMIT_BRANCH"
    - pip --version || true
    - python --version || true
    - ls -al . || true
    - pwd || true
    - whoami || true

lint:
  <<: *base_before_script
  before_script:
    # 先执行锚点中的debug命令，再追加专属命令
    - *base_before_script.before_script
    - pip install -r requirements-lint.txt
    - <some more lint specific commands>
  script:
    - echo "lint"

build:
  <<: *base_before_script
  before_script:
    - *base_before_script.before_script
    - pip install -r requirements-build.txt
    - <some more build specific commands>
  script:
    - echo "build"

test:
  <<: *base_before_script
  before_script:
    - *base_before_script.before_script
    - pip install -r requirements-test.txt
    - <some more test specific commands>
  script:
    - echo "test"

方法3：脚本文件+全局引用（适合复杂场景） #

如果debug命令较多，可将其写入独立脚本文件（如debug.sh），通过全局配置调用脚本，再让任务的before_script引用全局配置后追加命令：

default:
  before_script:
    - chmod +x ./debug.sh && ./debug.sh

# debug.sh 内容示例
#!/bin/bash
echo "$CI_PROJECT_NAME"
echo "$CI_PIPELINE_SOURCE"
echo "$CI_DEFAULT_BRANCH"
echo "$CI_COMMIT_BRANCH"
pip --version || true
python --version || true
ls -al . || true
pwd || true
whoami || true

lint:
  before_script:
    - !reference [default, before_script]
    - pip install -r requirements-lint.txt
    - <some more lint specific commands>
  script:
    - echo "lint"

# build、test任务配置与lint类似

内容的提问来源于stack exchange，提问作者vvvvv