首先我需要说明的是，我是CI/CD和Gitlab的初学者，尽管如此，我还是设法拼凑出了（使用网络上的例子）这个“几乎”可以工作的管道配置：

image: mcr.microsoft.com/dotnet/sdk:6.0

variables:
  OBJECTS_DIRECTORY: 'obj'
  NUGET_PACKAGES_DIRECTORY: '.nuget'
  SOURCE_CODE_PATH: '*/*/'
  TAG_LATEST: $CI_REGISTRY_IMAGE/$CI_COMMIT_REF_NAME:latest
  TAG_COMMIT: $CI_REGISTRY_IMAGE/$CI_COMMIT_REF_NAME:$CI_COMMIT_SHORT_SHA

stages:
  - build
  - test
  - docker
  - deploy

cache:
  key: "$CI_JOB_STAGE-$CI_COMMIT_REF_SLUG"
  paths:
    - '$SOURCE_CODE_PATH$OBJECTS_DIRECTORY/project.assets.json'
    - '$SOURCE_CODE_PATH$OBJECTS_DIRECTORY/*.csproj.nuget.*'
    - '$NUGET_PACKAGES_DIRECTORY'
  policy: pull-push

before_script:
  - 'dotnet restore --packages $NUGET_PACKAGES_DIRECTORY'

build:
  stage: build
  script:
  - 'dotnet build --no-restore'

tests:
  stage: test
  script:
    - 'dotnet test --no-restore'

docker:
  stage: docker
  image: docker:latest
  services:
    - docker:18.09.7-dind
  variables:
    DOCKER_DRIVER: overlay2
    DOCKER_TLS_CERTDIR: ""
  only:
    - main
before_script:
    - apt-get update
    - apt-get install docker -y
  script:
    - docker login -u "gitlab-ci-token" -p "$CI_JOB_TOKEN" $CI_REGISTRY
    - docker build --tag "$CI_REGISTRY_IMAGE:$CI_COMMIT_SHORT_SHA" --tag "$CI_REGISTRY_IMAGE:latest" .
    - docker push "$CI_REGISTRY_IMAGE:$CI_COMMIT_SHORT_SHA"
    - docker push "$CI_REGISTRY_IMAGE:latest"

deploy:
  stage: deploy
  image: alpine:latest
  services:
  - docker:dind

  script:
  - chmod og= $ID_RSA
  - apk update && apk add openssh-client
  - ssh -i $ID_RSA -o StrictHostKeyChecking=no $SERVER_USER@$SERVER_IP "docker login -u gitlab-ci-token -p $CI_BUILD_TOKEN $CI_REGISTRY"
  - ssh -i $ID_RSA -o StrictHostKeyChecking=no $SERVER_USER@$SERVER_IP "docker pull $TAG_COMMIT"
  - ssh -i $ID_RSA -o StrictHostKeyChecking=no $SERVER_USER@$SERVER_IP "docker container rm -f atlas-portal-2.0 || true"
  - ssh -i $ID_RSA -o StrictHostKeyChecking=no $SERVER_USER@$SERVER_IP "docker run -d -p 80:80 --name atlas-portal-2.0 $TAG_COMMIT"
  environment: 
    name: production
  only:
  - main

当我运行这个管道时，它成功地到达了“docker”阶段，我希望在这里构建docker映像并将其存储在gitlab容器注册表中，但我得到了以下错误：
“/bin/bash：第149行：Docker：找不到命令”
我知道我需要在docker镜像中“安装”docker，这个镜像将被构建并存储在gitlab中，但是我不知道该如何去做。
而一旦我过了这个“ Docker ”阶段，我就有信心“部署”阶段也会失败。我是个新手...