云原生之旅 - 11）基于 Kubernetes 动态伸缩 Jenkins Build Agents
前言上一篇文章 云原生之旅 - 10）手把手教你安装 Jenkins on Kubernetes 我们介绍了在 Kubernetes 上安装 Jenkins，本文介绍下如何设置k8s pod作为Jenkins 构建job的 agent。
Jenkins master 和 agent 均以 pod 的形式运行在 Kubernetes 节点上。Master 运行在其中一个节点上，其配置数据 Jenkins home 使用存储卷挂载，master pod重启不会导致数据丢失。agent 运行在各个节点上，根据需求动态创建并自动释放。这样做的好处很多，比如高可用，高伸缩性，资源利用率高。
关键词：Jenkins on Kubernetes 实践，Jenkins 和 Kubernetes，在Kubernetes上安装Jenkins，Jenkins 高可用安装，Jenkins 动态伸缩构建， Kubernetes Pod as Jenkins build agent
准备
[*]已搭建 Jenkins master on kubernetes 云原生之旅 - 10）手把手教你安装 Jenkins on Kubernetes
[*]准备一个 Service Account，对目标 cluster 具有k8s admin权限，以便部署。
[*]防火墙已开通 Jenkins 出站到Docker hub，方便 push/pull image
[*]防火墙已开通 Jenkins 到 目标 cluster，以便部署。
插件安装
[*]Kubernetes Plugin
[*]Google Kubernetes Engine Plugin (我的例子是部署到 GKE cluster)
Jenkins 配置
Manage Nodes and Clouds
1. Go to `Manage Jenkins` –> `Manage Nodes and Clouds`2. Click `Configure Clouds`3. Add a new Cloud select `Kubernetes`4. Click `Kubernetes Cloud Detail5. Enter `jenkins` namespace in `Kubernetes Namespace` field6. Click `Test Connection` --> result show `Connected to Kubernetes v1.22.12-gke.2300`7. Click `Save`8. Enter `http://jenkins-service.jenkins.svc.cluster.local:8080` in `Jenkins URL` field9. Enter `jenkins-agent:50000` in `Jenkins tunnel` fieldhttps://img2022.cnblogs.com/blog/713188/202211/713188-20221112105942329-845128190.png10. Click `Add Pod Template` then `Pod Template Details`
11. Input `Name`=`jenkins-agent`, `Namespace`=`jenkins`, `Labels`=`kubeagent` https://img2022.cnblogs.com/blog/713188/202211/713188-20221112110132594-308469795.png
12. (Optional) 如果不添加 container template, the Jenkins Kubernetes plugin will use the default JNLP image from the Docker hub to spin up the agents.如果你要覆盖默认的jnlp image 可以 Click `Add Container` to add Container Template,输入 `Name`=`jnlp`, `Docker Image`=`your_registry/jenkins/inbound-agent:4.11-1-jdk11`https://img2022.cnblogs.com/blog/713188/202211/713188-20221112110357492-228604842.png
Ensure that you remove the sleep and 9999999 default argument from the container template.
Manage Credentials
[*]Add `Usernames with password` for docker hub account/pwd，比如 wade_test_dockerhub
[*]Add `Google Service Account from private key` 比如 gcp_sa_json_key
Credentials 会在Jenkinsfile里面用到。
### 本文首发于博客园 https://www.cnblogs.com/wade-xu/p/16863955.html
Test a freestyle project
Go to Jenkins home –> New Item and create a freestyle project，命名为 quick-test在 job description 部分, add the label `kubeagent` for `Restrict where this project can be run`.https://img2022.cnblogs.com/blog/713188/202211/713188-20221112110719726-1402001349.png
这个label 和我们上面创建 pod template时用的label一致. 这样的话 Jenkins就知道用哪个 pod template 作为 agent container.
随便添加一个shell 作为build stepshttps://img2022.cnblogs.com/blog/713188/202211/713188-20221112110911309-196896784.png
点Build Now
查看Console OutputAgent jenkins-agent-l7hw9 is provisioned from template jenkins-agent
......
Building remotely on jenkins-agent-l7hw9 (kubeagent) in workspace /home/jenkins/agent/workspace/quick-test
$ /bin/sh -xe /tmp/jenkins17573873264046707236.sh
+ echo test pipeline
test pipeline
Finished: SUCCESS ### 本文首发于博客园 https://www.cnblogs.com/wade-xu/p/16863955.html
Jenkinsfile
CI
接着我们用 Jenkinsfile 写一个 Declarative pipeline - build/push docker image 到docker hub首先需要定义一个 pod.yaml 作为启动 agent 的containerhttps://images.cnblogs.com/OutliningIndicators/ContractedBlock.gifhttps://images.cnblogs.com/OutliningIndicators/ExpandedBlockStart.gifkind: Pod
spec:
containers:# list of containers that you want present for your build, you can define a default container in the Jenkinsfile
- name: maven
image: maven:3.5.4-jdk-8-slim
command: ["tail", "-f", "/dev/null"]# this or any command that is bascially a noop is required, this is so that you don't overwrite the entrypoint of the base container
imagePullPolicy: Always # use cache or pull image for agent
resources:# request and limit the resources your build contaienr
requests:
memory: 4Gi
cpu: 2
limits:
memory: 4Gi
cpu: 2
volumeMounts:
- mountPath: /root/.m2 # maven .m2 cache directory
name: maven-home
- name: git
image: bitnami/git:2.38.1
imagePullPolicy: IfNotPresent
command: ["tail", "-f", "/dev/null"]
resources: # limit the resources your build contaienr
limits:
cpu: 100m
memory: 256Mi
- name: kubectl-kustomize
image: line/kubectl-kustomize:1.25.3-4.5.7
imagePullPolicy: IfNotPresent
command: ["tail", "-f", "/dev/null"]
resources: # limit the resources your build contaienr
limits:
cpu: 100m
memory: 256Mi
- name: docker
image: docker:18.06.1
command: ["tail", "-f", "/dev/null"]
imagePullPolicy: Always
volumeMounts:
- name: docker
mountPath: /var/run/docker.sock # We use the k8s host docker engine
volumes:
- name: docker
hostPath:
path: /var/run/docker.sock
- name: maven-home
persistentVolumeClaim:
claimName: maven-repo-storagebuild-pod.yaml在Jenkinsfile里面定义agent 使用这个yaml file
agent {
kubernetes {
idleMinutes 3// how long the pod will live after no jobs have run on it
yamlFile './build-pod.yaml'// path to the pod definition relative to the root of our project
defaultContainer 'docker'// define a default container if more than a few stages use it, otherwise default to jnlp container
}下面步骤是 docker login/build/tag/push
environment { DOCKER_HUB_REGISTRY='https://index.docker.io/v1/' DOCKER_HUB_CREDS = credentials('wade_test_dockerhub') }stage('Build and Push Docker Image') {
steps {
script {
dir(dir_path) {
container('docker') {
// docker login, Using single-quotes instead of double-quotes when referencing these sensitive environment variables prevents this type of leaking.
sh 'echo $DOCKER_HUB_CREDS_PSW | docker login -u $DOCKER_HUB_CREDS_USR --password-stdin $DOCKER_HUB_REGISTRY'
// build image with git tag
sh """
docker build -t $PROJECT_IMAGE_WITH_TAG .
docker tag $PROJECT_IMAGE_WITH_TAG $DOCKER_HUB_CREDS_USR/$PROJECT_IMAGE_WITH_TAG
"""
// push image_tag to docker hub
sh """
docker push $DOCKER_HUB_CREDS_USR/$PROJECT_IMAGE_WITH_TAG
"""
}
}
}
}
}我这里没有选择用 docker.withRegistry
docker.withRegistry("$DOCKER_HUB_REGISTRY", "$DOCKER_HUB_CREDENTIAL") {}因为会有不安全的log提示
WARNING! Using --password via the CLI is insecure. Use --password-stdin.
CI + Kustomize + CD
这个例子是上面的 CI 之后 加上 - 利用 Kustomize build K8S resource manifests 然后 CD 到一个 Cluster
Kustomize 可以参考 云原生之旅 - 6）不能错过的一款 Kubernetes 应用编排管理神器 Kustomize
https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gifhttps://images.cnblogs.com/OutliningIndicators/ExpandedBlockStart.gif // assume your k8s manifests in another repo, mine is same repo, just in order to show git clone step
stage('Checkout K8S manifests') {
steps {
script {
dir(dir_path) {
container('git') {
if (! fileExists('learning_by_doing/README.md')) {
sh """
git clone https://github.com/wadexu007/learning_by_doing.git
ls -lhrt
"""
} else {
sh 'echo manifes repo already exist.'
}
}
}
}
}
}
stage('Build manifests with Kustomize') {
steps {
script {
dir(dir_path) {
container('kubectl-kustomize') {
sh """
cd learning_by_doing/Kustomize/demo-manifests/services/demo-app/dev/
kustomize edit set image $DOCKER_HUB_CREDS_USR/$PROJECT_IMAGE_WITH_TAG
kustomize build > $WORKSPACE/$dir_path/deployment.yaml
"""
}
}
}
}
}
stage('Deploy to GKE test cluster') {
environment{
PROJECT_ID = 'xperiences-eng-cn-dev'
CLUSTER_NAME = 'xpe-spark-test-gke'
REGION = 'asia-east2'
CREDENTIALS_ID = 'gcp_sa_json_key'
}
steps {
script {
dir(dir_path) {
container('kubectl-kustomize') {
sh """
chown 1000:1000 deployment.yaml
echo start to deploy to cluster $CLUSTER_NAME
"""
step([
$class: 'KubernetesEngineBuilder',
projectId: env.PROJECT_ID,
clusterName: env.CLUSTER_NAME,
location: env.REGION,
manifestPattern: 'deployment.yaml',
credentialsId: env.CREDENTIALS_ID,
verifyDeployments: false])
// verifyDeployments does not work for non-default namespace
}
}
}
}
}View Code
Pipeline: Input Step
这个例子是利用 Jenkins pipeline的 Input step 来做一个人工介入Approve的步骤。 然后再来一个多cluster 部署，选不同region 部署到不同的cluster的示例。 stage('Wait for SRE Approval') {
steps {
timeout(time:72, unit:'HOURS') {
input message: "Approved Prod deployment?", submitter: 'sre-team'
}
}
}
// deployment to multipe k8s clusters
stage('Deploy to GKE Prod cluster') {
environment{
PROJECT_ID = 'sre-cn-dev'
CREDENTIALS_ID = 'gcp_sa_json_key'
CLUSTER_COMMON_NAME = 'demo-gke-prod'
}
steps {
script {
env.REGION = input message: 'Choose which region you want to deploy?',
parameters: [choice(name: 'Region',
description: 'Select Region to Deloy',
choices: ['europe-west1', 'us-central1'])
]
dir(dir_path) {
if ( env.REGION == "europe-west1" ) {
def eu_cluster_name = env.CLUSTER_COMMON_NAME + "-eu"
container('kubectl-kustomize') {
sh "echo deploy to cluster $eu_cluster_name in region: $REGION"
}
}
if ( env.REGION == "us-central1" ) {
def us_cluster_name = env.CLUSTER_COMMON_NAME + "-us"
container('kubectl-kustomize') {
sh "echo deploy to cluster $us_cluster_name in region: $REGION"
}
}
}
}
}
}所有例子均在我的 github repo。
### 本文首发于博客园 https://www.cnblogs.com/wade-xu/p/16863955.html
测试
现在你可以创建一个 Pipeline 或者 Multibranch Pipeline job 来测试。Repository URL = `https://github.com/wadexu007/learning_by_doing`Script Path, e.g. `Jenkins/k8s_pod_as_build_agent/demo-app-java/Jenkinsfile` 你会看到每启动一个job 都会相应的产生一个pod 来作为Jenkins agent运行，结束后根据idleMinutes自动释放。 https://img2022.cnblogs.com/blog/713188/202211/713188-20221112131858338-1550544512.png总结
如果你已经成功创建并测试 CI/CD pipeline，可以继续加强，比如加上 Post notifications 最佳实践
[*]设置 resource requests and limits on each container in your Pod
[*]如果使用maven 构建 java项目，.m2 cache目录需要 mount 出来，这样加快后面的maven build速度。
[*]使用 Jenkins Shared Libraries 抽取Pipeline的共用代码
[*]在容器里构建容器化应用（Run docker in docker) 我的例子是通过 mount docker.sock 利用k8s 主机 docker engine来实现的，这种方式需要 privileges mode 不安全，推荐使用Kaniko，下一篇文章会介绍。
感谢阅读，如果您觉得本文的内容对您的学习有所帮助，您可以打赏和推荐，您的鼓励是我创作的动力。
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