Jenkins Pipeline 脚本优化实践：从繁琐到简洁

引言

在持续集成的过程中，Jenkins Pipeline 是非常关键的一环。它定义了如何自动编译、测试和部署代码。随着项目的不断发展，Pipeline 的复杂性也在不断上升，这就需要我们持续优化 Pipeline 脚本，以提高代码的可读性和维护性。本文将介绍一次从繁琐Pipeline脚本到精简Pipeline脚本的转化过程，以及这种转化所带来的好处。

原始的 Pipeline 脚本:

注： loader其实已经废弃了

pipeline {

    agent { label  "build01" }
    stages {
        stage("GetCode"){
            agent { label  "build01" }
            steps{
                script{
                    println("下载代码 --> 分支： ${env.branchName}")
                    checkout([$class: 'GitSCM', branches: [[name: "${env.branchName}"]],
                    doGenerateSubmoduleConfigurations: false,
                        extensions: [[$class: 'CloneOption', depth: 1, noTags: false, reference: '', shallow: true]],
                    submoduleCfg: [],
                        userRemoteConfigs: [[credentialsId: 'xxxxx',
                        url: "${env.gitHttpURL}"]]])
                }
            }
        }    
        stage('docker build dataloader-game-ucenter') {
            agent { label  "build01" }
            when {
                environment name: 'dataloader', value: 'true'
            }

            steps {
                sh ''' cd dataloader
                    docker build  --build-arg NODE_ENV=game-ucenter  -t swr.cn-north-4.myhuaweicloud.com/master-metaspace/dataloader-game-ucenter:$data .'''
                withCredentials([usernamePassword(credentialsId: 'hw-registry', passwordVariable: 'dockerPassword', usernameVariable: 'dockerUser')]) {
                    sh "docker login -u ${dockerUser} -p ${dockerPassword} swr.cn-north-4.myhuaweicloud.com"
                    sh "docker push swr.cn-north-4.myhuaweicloud.com/master-metaspace/dataloader-game-ucenter:$data"
                }
            }
        }
        stage('docker build datawriter-game-ucenter') {
            agent { label  "build01" }
            when {
                environment name: 'datawriter', value: 'true'
            }

            steps {
                sh ''' cd datawriter-game-ucenter
                    docker build  --build-arg NODE_ENV=game-ucenter  -t swr.cn-north-4.myhuaweicloud.com/master-metaspace/datawriter-game-ucenter:$data .'''
                withCredentials([usernamePassword(credentialsId: 'hw-registry', passwordVariable: 'dockerPassword', usernameVariable: 'dockerUser')]) {
                    sh "docker login -u ${dockerUser} -p ${dockerPassword} swr.cn-north-4.myhuaweicloud.com"
                    sh "docker push swr.cn-north-4.myhuaweicloud.com/master-metaspace/datawriter-game-ucenter:$data"
                }
            }
        }   
        stage('docker build game-ucenter') {
            agent { label  "build01" }
            when {
                environment name: 'game-ucenter', value: 'true'
            }

            steps {
                sh ''' cd game-ucenter
                    docker build  --build-arg NODE_ENV=game-ucenter  -t swr.cn-north-4.myhuaweicloud.com/master-metaspace/game-ucenter:$data .'''
                withCredentials([usernamePassword(credentialsId: 'hw-registry', passwordVariable: 'dockerPassword', usernameVariable: 'dockerUser')]) {
                    sh "docker login -u ${dockerUser} -p ${dockerPassword} swr.cn-north-4.myhuaweicloud.com"
                    sh "docker push swr.cn-north-4.myhuaweicloud.com/master-metaspace/game-ucenter:$data"
                }
            }
        }              
        stage('develop') {

            parallel {
                stage("develop datawriter-game-ucenter") {
                    when {
                        environment name: 'datawriter-game-ucenter', value: 'true'
                    }
                    agent { label  "huaweiyun-xx" }
                    steps {
                        sh "sed -e 's/{data}/$data/g' /home/jenkins/workspace/yaml/master-metaspace/datawriter-game-ucenter.tpl > /home/jenkins/workspace/yaml/master-metaspace/datawriter-game-ucenter.yaml"
                        sh "sudo kubectl apply -f /home/jenkins/workspace/yaml/master-metaspace/datawriter-game-ucenter.yaml --namespace=master-metaspace --context=master"
                    }
                }
                stage("develop dataloader-game-ucenter") {
                    when {
                        environment name: 'dataloader', value: 'true'
                    }
                    agent { label  "huaweiyun-xx" }
                    steps {
                        sh "sed -e 's/{data}/$data/g' /home/jenkins/workspace/yaml/master-metaspace/dataloader-game-ucenter.tpl > /home/jenkins/workspace/yaml/master-metaspace/dataloader-game-ucenter.yaml"
                        sh "sudo kubectl apply -f /home/jenkins/workspace/yaml/master-metaspace/dataloader-game-ucenter.yaml --namespace=master-metaspace --context=master"
                    }
                }
                stage("develop game-ucenter") {
                    when {
                        environment name: 'game-ucenter', value: 'true'
                    }
                    agent { label  "huaweiyun-xx" }
                    steps {
                        sh "sed -e 's/{data}/$data/g' /home/jenkins/workspace/yaml/master-metaspace/game-ucenter.tpl > /home/jenkins/workspace/yaml/master-metaspace/game-ucenter.yaml"
                        sh "sudo kubectl apply -f /home/jenkins/workspace/yaml/master-metaspace/game-ucenter.yaml --namespace=master-metaspace --context=master"
                    }
                }                                  
            }
        }
    }
}

在优化之前，我们的 Jenkins Pipeline 脚本中包含了多个独立定义的 stage，每个 stage 中都有重复的结构和指令：

1. 明确指定了 agent。
2. 在每个 stage 的 steps 中，都使用了类似的脚本来操作 git、构建 docker 镜像和部署到 Kubernetes。
3. 使用了冗长的 shell 脚本来绑定变量和执行部署。

这种写法虽然直观，但存在以下问题：

• 代码冗余：相同的任务（例如构建与部署）重复编写了多次。
• 低效的修改：一旦需要调整构建或部署流程，需要同时修改多个类似的代码段。
• 可读性差：过于细碎的脚本内容使得新成员阅读和理解这个 Pipeline 变得困难。

转化的原因与过程

简化 agent 的声明

pipeline {
    agent none // Use none at the top level, each stage will define its own agent.
    }

在原始脚本中，每个 stage 都重复指定相同的 agent，这是不必要的。转化后，我们在 pipeline 的顶层使用 agent none 声明，表示不在这一层级指定执行者，这样各个 stage 就可以根据需求独立地声明自己的 agent。

将环境变量统一管理

我们创建一个 environment 部分来集中定义环境变量，简化了变量的管理，并且当需要修改时只要在一个地方进行调整即可。

    environment {
        REGISTRY = "swr.cn-north-4.myhuaweicloud.com/master-metaspace"
        KUBE_CONFIG = "--namespace=master-metaspace --context=master"
        KUBE_YAML_PATH = "/home/jenkins/workspace/yaml/master-metaspace"
        // Assume that 'data' is defined elsewhere or injected as a parameter.
    }

使用共用方法减少代码重复

对于 Docker 镜像的构建和推送操作，每个应用几乎执行相同的步骤。我们提取了一个方法 buildAndPushDockerImage 来代替在每个 stage 里重复定义的步骤，这样不但减小了脚本体积，也提升了代码的复用性。

def buildAndPushDockerImage(String imageName, String tag) {
    sh "cd $imageName && docker build --build-arg NODE_ENV=$imageName -t $REGISTRY/$imageName:$tag ."
    withCredentials([usernamePassword(credentialsId: 'hw-registry', passwordVariable: 'dockerPassword', usernameVariable: 'dockerUser')]) {
        sh "docker login -u $dockerUser -p $dockerPassword $REGISTRY"
        sh "docker push $REGISTRY/$imageName:$tag"
    }
}

同理，部署到 Kubernetes 的指令也被提取到了 deployToKubernetes 方法中，进一步去重。

def deployToKubernetes(String kubernetesComponent) {
    String templateFile = "${KUBE_YAML_PATH}/${kubernetesComponent}.tpl"
    String outputFile = "${KUBE_YAML_PATH}/${kubernetesComponent}.yaml"
    sh "sed -e 's/{data}/$data/g' $templateFile > $outputFile"
    sh "sudo kubectl apply -f $outputFile $KUBE_CONFIG"
}

结构的并行化

将 Docker 构建步骤组合为一个并行执行的 stage，这样不仅可以缩短整个流水线的执行时间，还可以使得结构更加清晰。

        stage("Docker Builds") {
            parallel {
                stage('Build dataloader-game-ucenter') {
                    agent { label "build01" }
                    when { environment name: 'dataloader', value: 'true' }
                    steps {
                        buildAndPushDockerImage("dataloader-game-ucenter", env.data, env.BASE_WORKSPACE)
                    }
                }
                stage('Build datawriter-game-ucenter') {
                    agent { label "build01" }
                    when { environment name: 'datawriter', value: 'true' }
                    steps {
                        buildAndPushDockerImage("datawriter-game-ucenter", env.data, env.BASE_WORKSPACE)
                    }
                }
                stage('Build game-ucenter') {
                    agent { label "build01" }
                    when { environment name: 'game-ucenter', value: 'true' }
                    steps {
                        buildAndPushDockerImage("game-ucenter", env.data, env.BASE_WORKSPACE)
                    }
                }
            }
        }

转化后的好处

转换后的pipeline如下：

pipeline {
    agent none // Use none at the top level, each stage will define its own agent.

    environment {
        REGISTRY = "swr.cn-north-4.myhuaweicloud.com/master-metaspace"
        KUBE_CONFIG = "--namespace=master-metaspace --context=master"
        KUBE_YAML_PATH = "/home/jenkins/workspace/yaml/master-metaspace"
        // Assume that 'data' is defined elsewhere or injected as a parameter.
        BASE_WORKSPACE = "xxxxxxx" // 定义一个基础工作空间路径
    }

    stages {
        stage("GetCode") {
            agent { label "build01" }
            steps {
                script {
                    checkout scm: [
                        $class: 'GitSCM',
                        branches: [[name: env.branchName]],
                        extensions: [[$class: 'CloneOption', depth: 1, noTags: false, shallow: true]],
                        userRemoteConfigs: [[credentialsId: 'xxxx', url: env.gitHttpURL]]
                    ]
                }
            }
        }
        
        stage("Docker Builds") {
            parallel {
                stage('Build dataloader-game-ucenter') {
                    agent { label "build01" }
                    when { environment name: 'dataloader', value: 'true' }
                    steps {
                        buildAndPushDockerImage("dataloader-game-ucenter", env.data, env.BASE_WORKSPACE)
                    }
                }
                stage('Build datawriter-game-ucenter') {
                    agent { label "build01" }
                    when { environment name: 'datawriter', value: 'true' }
                    steps {
                        buildAndPushDockerImage("datawriter-game-ucenter", env.data, env.BASE_WORKSPACE)
                    }
                }
                stage('Build game-ucenter') {
                    agent { label "build01" }
                    when { environment name: 'game-ucenter', value: 'true' }
                    steps {
                        buildAndPushDockerImage("game-ucenter", env.data, env.BASE_WORKSPACE)
                    }
                }
            }
        }
        
        stage('Development Deployment') {
            parallel {
                stage("Deploy datawriter-game-ucenter") {
                    when { environment name: 'datawriter-game-ucenter', value: 'true' }
                    agent { label  "huaweiyun-xx" }
                    steps {
                        deployToKubernetes("datawriter-game-ucenter")
                    }
                }
                stage("Deploy dataloader-game-ucenter") {
                    when { environment name: 'dataloader', value: 'true' }
                    agent { label  "huaweiyun-xx" }
                    steps {
                        deployToKubernetes("dataloader-game-ucenter")
                    }
                }
                stage("Deploy game-ucenter") {
                    when { environment name: 'game-ucenter', value: 'true' }
                    agent { label  "huaweiyun-xx" }
                    steps {
                        deployToKubernetes("game-ucenter")
                    }
                }
            }
        }
    }
}

// Define methods outside pipeline to avoid repetition

def buildAndPushDockerImage(String imageName, String tag, String workspacePath) {
    sh "cd ${workspacePath} && echo 'Current directory: \$(pwd)'" // 使用基础工作空间变量
    sh "cd ${workspacePath}/${imageName}&& docker build --build-arg NODE_ENV=$imageName -t $REGISTRY/$imageName:$tag ."
    withCredentials([usernamePassword(credentialsId: 'hw-registry', passwordVariable: 'dockerPassword', usernameVariable: 'dockerUser')]) {
        sh "docker login -u $dockerUser -p $dockerPassword $REGISTRY"
        sh "docker push $REGISTRY/$imageName:$tag"
    }
}

def deployToKubernetes(String kubernetesComponent) {
    String templateFile = "${KUBE_YAML_PATH}/${kubernetesComponent}.tpl"
    String outputFile = "${KUBE_YAML_PATH}/${kubernetesComponent}.yaml"
    sh "sed -e 's/{data}/$data/g' $templateFile > $outputFile"
    sh "sudo kubectl apply -f $outputFile $KUBE_CONFIG"
}

• 代码结构清晰：每个阶段的职责更加明确，整个 Pipeline 结构变得简单易懂。
• 维护成本降低：通用操作被封装成方法，避免了重复代码，当流程需要修改时，只需在一个地方更新。
• 执行效率提升：使用 parallel 来并行构建 Docker 镜像降低了整体构建时间。
• 可扩展性增加：如果将来要增加新的镜像构建或者 Kubernetes 部署，只需很少的修改即可。

总结来说，通过优化 Jenkins Pipeline 脚本，我们不仅提高了流程的效率，还大大减小了维护成本。在持续集成和持续部署的实践中，拥有一个简洁和高效的 Pipeline 是至关重要的。

特意强调的

environment 添加了BASE_WORKSPACE，why？
在Jenkins中，当你在一个Pipeline中使用并行步骤执行作业时，默认情况下，每个并行的分支都会创建一个新的工作空间目录，格式一般为workspace@2、workspace@3等，这样做是为了避免各个分支之间产生文件系统上的冲突。
这样带来的后果就是：

构建过程中就会出现No such file or directory这样的报错：

所以这里引入了BASE_WORKSPACE

    environment {
        REGISTRY = "swr.cn-north-4.myhuaweicloud.com/master-metaspace"
        KUBE_CONFIG = "--namespace=master-metaspace --context=master"
        KUBE_YAML_PATH = "/home/jenkins/workspace/yaml/master-metaspace"
        // Assume that 'data' is defined elsewhere or injected as a parameter.
        BASE_WORKSPACE = "/home/jenkins2/workspace/test6" // 定义一个基础工作空间路径
    }

build过程中引入了:

sh "cd ${workspacePath} && echo 'Current directory: \$(pwd)'"

确保并行步骤中引用到正确的工作空间目录!

注： 以上脚本代码转换后的pipeline使用chatgpt生成，并多次修订！