安卓自动化之旅（七）——短篇，优化Docker缓存（短篇）

[soapgu]

在 安卓自动化之旅（六）——使用Coding&Docker持续集成安卓项目这篇里面留了一个小尾巴，这次一并补上。

• 正文

参考以下内容

• 缓存 Docker 基础镜像

增加两个stage，直接上脚本代码

pipeline {
  agent any
  environment{
    DOCKER_CACHE_EXISTS = fileExists '/root/.cache/docker/jre-11.tar'
  }
  stages {
    stage('检出') {
      steps {
        checkout([$class: 'GitSCM',
        branches: [[name: GIT_BUILD_REF]],
        userRemoteConfigs: [[
          url: GIT_REPO_URL,
          credentialsId: CREDENTIALS_ID
        ]]])
      }
    }
    stage('加载缓存') {
      when { expression { DOCKER_CACHE_EXISTS == 'true' } }
      steps {
        sh 'docker load -i /root/.cache/docker/jre-11.tar'
      }
    }
    stage('编译构建') {
      agent {
        docker {
          reuseNode 'true'
          registryUrl 'https://shgbit-docker.pkg.coding.net'
          registryCredentialsId "${env.DOCKER_REGISTRY_CREDENTIALS_ID}"
          image 's365/dockers/jre-11:1.0'
          args '-v "/root/programs/android-sdk:/root/programs/android-sdk" -v /root/.gradlecache/:/root/.gradle/'
        }

      }
      steps {
        dir('android/projects/assistant') {
          sh 'chmod +x gradlew'
          sh './gradlew clean && rm -rf ./app/build/'
          sh './gradlew assembleRelease'
        }
      }
    }
    stage('生成缓存') {
      when { expression { DOCKER_CACHE_EXISTS == 'false' } }
      steps {
        sh 'mkdir -p /root/.cache/docker/'
        sh 'docker save -o /root/.cache/docker/jre-11.tar shgbit-docker.pkg.coding.net/s365/dockers/jre-11:1.0'
      }
    }
    stage('上传到 Generic') {
      steps {
        dir('android/projects/assistant/app/build/outputs/apk/release') {
          codingArtifactsGeneric(credentialsId: "${CODING_ARTIFACTS_CREDENTIALS_ID}", withBuildProps: true, files: '*.apk', repoName: "${GENERIC_REPO_NAME}", version: "${CI_BUILD_NUMBER}")
        }
      }
    }
  }
}

说明

1. 声明环境变量 DOCKER_CACHE_EXISTS
2. 在加载Docker agent 前的Stage先加入加载缓存的stage
3. 在结束前，加入生成缓存stage
4. 增加/root/.cache/缓存目录

• 原理

主要的疑惑点在于，Jenkins怎么知道我已经加载好了Docker，不需要再pull了？？
我们直接从日志里去找答案
没有加载缓存前

[2021-09-22 16:36:20] [Pipeline] {
[2021-09-22 16:36:20] [Pipeline] isUnix
[2021-09-22 16:36:20] [Pipeline] sh
[2021-09-22 16:36:20] + docker inspect -f . s365/dockers/jre-11:1.0
[2021-09-22 16:36:20] 
[2021-09-22 16:36:20] Error: No such object: s365/dockers/jre-11:1.0
[2021-09-22 16:36:20] [Pipeline] isUnix
[2021-09-22 16:36:20] [Pipeline] sh
[2021-09-22 16:36:21] + docker inspect -f . shgbit-docker.pkg.coding.net/s365/dockers/jre-11:1.0
[2021-09-22 16:36:21] 
[2021-09-22 16:36:21] Error: No such object: shgbit-docker.pkg.coding.net/s365/dockers/jre-11:1.0
[2021-09-22 16:36:21] [Pipeline] isUnix
[2021-09-22 16:36:21] [Pipeline] sh
[2021-09-22 16:36:21] + docker pull shgbit-docker.pkg.coding.net/s365/dockers/jre-11:1.0
[2021-09-22 16:36:21] 1.0: Pulling from s365/dockers/jre-11
[2021-09-22 16:36:21] a330b6cecb98: Pulling fs layer
[2021-09-22 16:36:21] 752cb4b38af3: Pulling fs layer
[2021-09-22 16:36:21] 3e2cf95ad979: Pulling fs layer
...

加载缓存后

[2021-09-22 16:39:22] [Pipeline] {
[2021-09-22 16:39:23] [Pipeline] isUnix
[2021-09-22 16:39:23] [Pipeline] sh
[2021-09-22 16:39:23] + docker inspect -f . s365/dockers/jre-11:1.0
[2021-09-22 16:39:23] 
[2021-09-22 16:39:23] Error: No such object: s365/dockers/jre-11:1.0
[2021-09-22 16:39:23] [Pipeline] isUnix
[2021-09-22 16:39:23] [Pipeline] sh
[2021-09-22 16:39:23] + docker inspect -f . shgbit-docker.pkg.coding.net/s365/dockers/jre-11:1.0
[2021-09-22 16:39:23] .
[2021-09-22 16:39:23] [Pipeline] withDockerContainer
[2021-09-22 16:39:23] Jenkins does not seem to be running inside a container
[2021-09-22 16:39:23] $ docker run -t -d -u 0:0 -v /root/programs/android-sdk

还是比较明显的。
Coding会自动生成docker inspect -f的脚本来判断是否已经缓存了Docker

• Docker inspect 命令

• 总结

上次没一起弄是因为我的Docker镜像比较小，弄不弄差不多。
但是为了整体性考虑，还是要考虑优化的。对比下优化前后，基本上优化了7s左右，但这个镜像只有140M不到。如果是一个1G的大镜像那空间就很大了。