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Tekton系列之实践篇-使用Tekton Trigger让Tekton使用更简单

乔克
2022-04-14 / 0 评论 / 0 点赞 / 492 阅读 / 15,182 字 / 正在检测是否收录...
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在《Tekton实践篇-如何用Jenkins来管理Tekton》我们介绍了如何使用Jenkins来管理Tekton,这种方式是运维主动式管理,也就是需要运维去触发发布,那有没有可能让自动触发Tekton PipelineRun的运行呢?

答案是有的,也就是这篇文章分享的Tekton Trigger。

什么是Tekton Trigger?

Tekton Trigger是Tekton的一个组件,它可以从各种来源的事件中检测并提取需要信息,然后根据这些信息来运行TaskRun和PipelineRun,还可以将提取出来的信息传递给它们以满足不同的运行要求。

其核心组件如下:

  • EventListener:时间监听器,是外部事件的入口 ,通常需要通过HTTP方式暴露,以便于外部事件推送,比如配置Gitlab的Webhook。
  • Trigger:指定当EventListener检测到事件发生时会发生什么,它会定义TriggerBinding、TriggerTemplate以及可选的Interceptor。
  • TriggerTemplate:用于模板化资源,根据传入的参数实例化Tekton对象资源,比如TaskRun、PipelineRun等。
  • TriggerBinding:用于捕获事件中的字段并将其存储为参数,然后会将参数传递给TriggerTemplate。
  • ClusterTriggerBinding:和TriggerBinding相似,用于提取事件字段,不过它是集群级别的对象。
  • Interceptor:拦截器,在TriggerBinding之前运行,用于负载过滤、验证、转换等处理,只有通过拦截器的数据才会传递给TriggerBinding。

工作原理图如下:

image.png

下面会详细介绍Trigger 的CRD对象。

Trigger CRD对象

TriggerTemplate

TriggerTemplate可以模块化Tekton资源的资源,可以使传入的参数在资源模板中的任何位置被使用,它就好比我们定义了一个对象,这个对象可以接收外部的参数,在对象内部把接收到的参数再传递给Tekton资源对象进行使用。

TriggerTemplate的定义很简单,如下:

apiVersion: triggers.tekton.dev/v1beta1
kind: TriggerTemplate
metadata:
  name: pipeline-template
spec:
  params:  # 参数的定义,从外部接收的参数
  - name: gitrevision
    description: The git revision
    default: main
  - name: gitrepositoryurl
    description: The git repository url
  - name: message
    description: The message to print
    default: This is the default message
  - name: contenttype
    description: The Content-Type of the event
  resourcetemplates: # 资源模板,将参数传递给资源模板,实例化一个PipelineRun对象
  - apiVersion: tekton.dev/v1beta1
    kind: PipelineRun
    metadata:
      generateName: simple-pipeline-run-
    spec:
      pipelineRef:
        name: simple-pipeline
      params:
      - name: message
        value: $(tt.params.message)
      - name: contenttype
        value: $(tt.params.contenttype)
      resources:
      - name: git-source
        resourceSpec:
          type: git
          params:
          - name: revision
            value: $(tt.params.gitrevision)
          - name: url
            value: $(tt.params.gitrepositoryurl)

从上面可以看出,resourcetemplates字段中就是定义的资源模板,上面定义的PipelineRun的资源,里面的语法和定义一个PipelineRun CRD一致,就像Deployment的Template中定义的Pod资源和单独定义Pod资源的语义一样。

params字段定义我们需要从外部获得的参数,这个参数后续会传递给resourcetemplates以完成其资源实例化。

TriggerBinding

TriggerBinding用于将事件进行绑定,通过捕获事件中的字段并将其存储为参数。

其定义方式如下:

apiVersion: triggers.tekton.dev/v1beta1
kind: TriggerBinding
metadata:
  name: pipeline-binding
spec:
  params:
  - name: gitrevision
    value: $(body.head_commit.id)
  - name: gitrepositoryurl
    value: $(body.repository.url)
  - name: contenttype
    value: $(header.Content-Type)

TriggerBinding接收从EventListener传递过来的参数,然后传给TriggerTemplate,在TriggerTemplate上实例化资源对象。

TriggerBinding提供TriggerTemplate需要的参数,参数以key-value的方式存储并传递。其中的value是通过$()中包裹得JSONPath表达式来提取(https://tekton.dev/docs/triggers/triggerbindings/)。

Trigger

用于指定当事件发生时需要做什么,它会定义TriggerBinding、TriggerTemplate以及可选的Interceptor。

如下:

apiVersion: triggers.tekton.dev/v1beta1
kind: Trigger
metadata:
  name: trigger
spec:
  interceptors:
    - ref:
        name: "cel"
      params:
        - name: "filter"
          value: "header.match('X-GitHub-Event', 'pull_request')"
        - name: "overlays"
          value:
            - key: extensions.truncated_sha
              expression: "body.pull_request.head.sha.truncate(7)"
  bindings:
  - ref: pipeline-binding
  template:
    ref: pipeline-template

上面定义了interceptorsbindingstemplate,一当EventListener收到事件,就会触发这个Trigger,先经过interceptors进行拦截筛选,然后再传给bindingstemplate

ClusterTriggerBinding

ClusterTriggerBinding和TriggerBinding功能一样,从名字就可以看到,ClusterTriggerBinding是集群级别的,可以作用于任何namespace。

其定义和TriggerBinding一样,如下:

apiVersion: triggers.tekton.dev/v1beta1
kind: ClusterTriggerBinding
metadata:
  name: pipeline-clusterbinding
spec:
  params:
    - name: gitrevision
      value: $(body.head_commit.id)
    - name: gitrepositoryurl
      value: $(body.repository.url)
    - name: contenttype
      value: $(header.Content-Type)

Interceptor

Interceptor是在TriggerBinding运行之前的事件处理器,可以做一些预处理,比如账户密码验证,再比如一些事件方式验证,如gitlab的push event。只有通过了Interceptor,才会把有效数据传递给TriggerBinding。

Tekton Trigger目前支持两种Interceptor的实现方式:

  • 独立Interceptor
  • 传统Interceptor(将被废弃)

独立Interceptor是ClusterInterceptor自定义资源的实例,可以在下面介绍的EventListener中引用这些Interceptor以及所需的参数。传统的Interceptor就是在EventListener中完全定义,不过这种方式将被废弃。

目前已经内置了以下Interceptor:

  • Webhook Interceptor
  • Github Interceptor
  • Gitlab Interceptor
  • Bitbucket Interceptor
  • CEL Interceptor

这里以Gitlab Interceptor为例。Gitlab Interceptor包括验证和过滤的逻辑,它可以验证Webhook的来源,也可以验证指定标准过滤传入的事件。如下:

interceptors:
- ref:
    name: "gitlab"
  params:
  - name: "secretRef"
    value:
      secretName: foo
      secretKey: bar
  - name: "eventTypes"
    value: ["Push Hook"]

也可以直接在EventListener中定义,如下:

apiVersion: triggers.tekton.dev/v1alpha1
kind: EventListener
metadata:
  name: gitlab-listener-interceptor
spec:
  serviceAccountName: tekton-triggers-example-sa
  triggers:
    - name: foo-trig
      interceptors:
        - gitlab:
            secretRef:
              secretName: foo
              secretKey: bar
            eventTypes:
              - Push Hook
      bindings:
        - ref: pipeline-binding
      template:
        ref: pipeline-template

EventListener

EventListener是一个Kubernetes对象,用于监听Kubernetes上指定端口的事件,然后会接收传入的事件并指定一个或多个触发器。

EventListener实际上是Tekton的另一种客户端形式,只是它是基于HTTP事件的,通过HTTP的方式可以绕过常规的认证路径,比如kubeconfig等,我们知道,任何需要通过kube-apiserver的事件都需要认证、鉴权等一系列操作,那HTTP方式是如何实现的呢?我们在创建一个简单的nginx deployment的时候,可以看到yaml文件里会自动生成一个default的serviceaccount,这个default就是用于认证、鉴权的。所以要使用EventListener,就需要让它拥有自己的serviceaccount,并且这个serviceaccount需要Tekton资源操作的权限才能让Event正常的和Tekton进行交互。

EventListener的定义示例如下:

apiVersion: triggers.tekton.dev/v1alpha1
kind: EventListener
metadata:
  name: gitlab-listener
spec:
  serviceAccountName: tekton-triggers-example-sa
  triggers:
    - name: gitlab-push-events-trigger
      interceptors:
        - name: "verify-gitlab-payload"
          ref:
            name: "gitlab"
            kind: ClusterInterceptor
          params:
            - name: secretRef
              value:
                secretName: "gitlab-secret"
                secretKey: "secretToken"
            - name: eventTypes
              value:
                - "Push Hook"
      bindings:
        - name: gitrevision
          value: $(body.checkout_sha)
        - name: gitrepositoryurl
          value: $(body.repository.git_http_url)
      template:
        spec:
          params:
            - name: gitrevision
            - name: gitrepositoryurl
          resourcetemplates:
            - apiVersion: tekton.dev/v1alpha1
              kind: TaskRun
              metadata:
                generateName: gitlab-run-
              spec:
                taskSpec:
                  inputs:
                    resources:
                      - name: source
                        type: git
                  steps:
                    - image: ubuntu
                      script: |
                        #! /bin/bash
                        ls -al $(inputs.resources.source.path)
                inputs:
                  resources:
                    - name: source
                      resourceSpec:
                        type: git
                        params:
                          - name: revision
                            value: $(tt.params.gitrevision)
                          - name: url
                            value: $(tt.params.gitrepositoryurl)

Trigger安装

上面简单介绍了一下Trigger的常用功能,更多的可以到官方文档(https://tekton.dev/docs/triggers/)进行学习。

下面我们将正式的把之前的Pipeline流程接入Trigger,实现开发人员推送代码,通过Webhook自动触发对应的PipelineRun。

首先我们需要安装Trigger(https://tekton.dev/docs/triggers/install/)。

安装的时候选择对应的版本安装,如果Kubernetes集群版本太低,会导致安装失败。

kubectl apply --filename https://storage.googleapis.com/tekton-releases/triggers/latest/release.yaml
kubectl apply --filename https://storage.googleapis.com/tekton-releases/triggers/latest/interceptors.yaml

不过由于网络原因,直接按着官方文档进行安装是下载不了,我将自己用到的上传到了仓库(https://gitee.com/coolops/tekton-install/tree/master/trigger),有需要的自己去下载。

安装完成后,可以看到如下Pod。

# kubectl get po -n tekton-pipelines 
NAME                                                 READY   STATUS    RESTARTS   AGE
tekton-dashboard-565c78b68d-6fjdz                    1/1     Running   12         32d
tekton-pipelines-controller-75c456df85-qxvq2         1/1     Running   5          32d
tekton-pipelines-webhook-5bc8d6b7c4-w6pdn            1/1     Running   5          32d
tekton-triggers-controller-686c6c8f79-fp7wd          1/1     Running   0          9m37s
tekton-triggers-core-interceptors-5d77595f79-8q9hb   1/1     Running   0          10s
tekton-triggers-webhook-76c55d6799-h997b             1/1     Running   0          9m36s

使用Tekton Trigger

上面已经安装好了Tekton Trigger,下面我们将正式接入Tekton Trigger实现自动持续部署。

定义Trigger Template

回看《Tekton系列之实践篇-由Jenkins改成Tekton》中的PipelineRun的YAML文件,可以看到有参数revision、git_url、imageUrl、imageTag、namespace等,所以在定义Trigger Template的时候需要这些参数传递进去。

apiVersion: triggers.tekton.dev/v1beta1 
kind: TriggerTemplate
metadata:
  name: trigger-rd-pipeline-template
spec:
  params:
    - name: gitrevision
      description: The git revision
      default: master
    - name: gitrepositoryurl
      description: The git repository url
    - name: namespace
      description: The namespace to create the resources
      default: tekton-devops-pipeline
    - name: projectname
      description: The project name
    - name: imagetag
      description: The image tag
      default: latest
  resourcetemplates:
    - apiVersion: tekton.dev/v1alpha1
      kind: PipelineRun
      metadata:
        name: rd-pipeline-run-$(uid)
        namespace: $(tt.params.namespace)
      spec:
        serviceAccountName: tekton-build-sa
        params: 
        - name: revision
          value: $(tt.params.gitrevision)
        - name: git_url
          value: $(tt.params.gitrepositoryurl)
        - name: imageUrl
          value: registry.cn-hangzhou.aliyuncs.com/coolops/$(tt.params.projectname)
        - name: imageTag
          value: latest
        - name: pathToDockerfile
          value: Dockerfile
        - name: chart_username
          value: xxx
        - name: chart_password
          value: xxx
        - name: app_name
          value: hello-world
        - name: namespace
          value: default
        - name: sonar_username
          value: xxxx
        - name: sonar_password
          value: xxxx
        - name: sonar_url
          value: http://sonarqube.coolops.cn
        pipelineRef:
          name: rd-pipeline
        workspaces:
        - name: rd-repo-pvc
          volumeClaimTemplate:
            spec:
              accessModes:
              - ReadWriteOnce
              storageClassName: local 
              resources:
                requests:
                  storage: 1Gi
        - name: docker-config
          secret:
            secretName: docker-config
        - name: kubernetes-config
          secret:
            secretName: kubernetes-config

定义Trigger Binding

Trigger Template的入参都可以通过PushEvent中获取,PushEvent里的数据需要通过Trigger Binding来绑定。

apiVersion: triggers.tekton.dev/v1beta1
kind: TriggerBinding
metadata:
  name: trigger-rd-pipeline-bingding
  namespace: tekton-devops-pipeline
spec:
  params:
    - name: gitrevision
      value: $(body.ref)
    - name: namespace
      value: tekton-devops-pipeline
    - name: gitrepositoryurl
      value: $(body.project.git_http_url)
    - name: projectname
      value: $(body.project.name)

定义EventListener

上面创建好Trigger Template和Trigger Binding,接下来就是创建EventListener,把Template和Binding关联起来。

apiVersion: triggers.tekton.dev/v1beta1
kind: EventListener
metadata:
  name: trigger-rd-pipeline-eventlistener
spec:
  serviceAccountName: tekton-triggers-gitlab-sa
  triggers:
    - bindings:
        - ref: trigger-rd-pipeline-bingding
      template:
        ref: trigger-rd-pipeline-template

这里的tekton-triggers-gitlab-sa是需要我们创建的,如下:

apiVersion: v1
kind: ServiceAccount
metadata:
  name: tekton-triggers-gitlab-sa
secrets:
- name: gitlab-secret
- name: gitlab-auth
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: tekton-triggers-gitlab-minimal
rules:
  # Permissions for every EventListener deployment to function
  - apiGroups: ["triggers.tekton.dev"]
    resources: ["eventlisteners", "triggerbindings", "triggertemplates","clustertriggerbindings", "clusterinterceptors","triggers"]
    verbs: ["get","list","watch"]
  - apiGroups: [""]
    # secrets are only needed for Github/Gitlab interceptors, serviceaccounts only for per trigger authorization
    resources: ["configmaps", "secrets", "serviceaccounts"]
    verbs: ["get", "list", "watch"]
  # Permissions to create resources in associated TriggerTemplates
  - apiGroups: ["tekton.dev"]
    resources: ["pipelineruns", "pipelineresources", "taskruns"]
    verbs: ["create"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: tekton-triggers-gitlab-binding
subjects:
  - kind: ServiceAccount
    name: tekton-triggers-gitlab-sa
    namespace: tekton-devops-pipeline
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: tekton-triggers-gitlab-minimal

现在需要新增一个Gitlab的Webhook的Secret Token,如下:

apiVersion: v1
kind: Secret
metadata:
  name: gitlab-secret
type: Opaque
stringData:
  secretToken: "coolops"

当创建完EventListener过后,会在当前namespace下生成一个service和deployment,如下:

# kubectl get all | grep event
pod/el-trigger-rd-pipeline-eventlistener-674768c8d5-p8z66             2/2     Running     2          128m
service/el-trigger-rd-pipeline-eventlistener   ClusterIP   10.98.84.33      <none>        8080/TCP   128m
deployment.apps/el-trigger-rd-pipeline-eventlistener   1/1     1            1           128m
replicaset.apps/el-trigger-rd-pipeline-eventlistener-674768c8d5   1         1         1       128m

我们需要把这个service暴露出去,创建Ingress如下:

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: el-trigger-test-eventlistener
spec:
  rules:
  - host: hello-word.webhook.coolops.cn
    http:
      paths:
      - backend:
          serviceName: el-trigger-rd-pipeline-eventlistener 
          servicePort: 8080

创建Webhook

上面已经把EventListener暴露出来了,下面就在代码仓库中创建Webhook。

由于我的代码放在私有Gitlab中的,配置如下(由于内网,就直接使用了NodePort暴露EventListener):

image.png

然后可以测试一下,并查看更多的信息。

image.png

需要的信息都是从Request中获取,如下:

{
  "object_kind": "push",
  "event_name": "push",
  "before": "77e1901516fc2ee1a47b03bb4bfc63ca02e6b23d",
  "after": "ac84d875c6094b5feebd477809a2021fd745c9df",
  "ref": "refs/heads/master",
  "checkout_sha": "ac84d875c6094b5feebd477809a2021fd745c9df",
  "message": null,
  "user_id": 1,
  "user_name": "Administrator",
  "user_username": "root",
  "user_email": "",
  "user_avatar": "https://www.gravatar.com/avatar/e64c7d89f26bd1972efa854d13d7dd61?s=80&d=identicon",
  "project_id": 2,
  "project": {
    "id": 2,
    "name": "Devops Hello World",
    "description": "",
    "web_url": "http://192.168.205.128/root/devops-hello-world",
    "avatar_url": null,
    "git_ssh_url": "git@192.168.205.128:root/devops-hello-world.git",
    "git_http_url": "http://192.168.205.128/root/devops-hello-world.git",
    "namespace": "Administrator",
    "visibility_level": 0,
    "path_with_namespace": "root/devops-hello-world",
    "default_branch": "master",
    "ci_config_path": null,
    "homepage": "http://192.168.205.128/root/devops-hello-world",
    "url": "git@192.168.205.128:root/devops-hello-world.git",
    "ssh_url": "git@192.168.205.128:root/devops-hello-world.git",
    "http_url": "http://192.168.205.128/root/devops-hello-world.git"
  },
  "commits": [
    {
      "id": "ac84d875c6094b5feebd477809a2021fd745c9df",
      "message": "ceshi ",
      "title": "ceshi ",
      "timestamp": "2022-03-30T08:54:11+00:00",
      "url": "http://192.168.205.128/root/devops-hello-world/-/commit/ac84d875c6094b5feebd477809a2021fd745c9df",
      "author": {
        "name": "coolops",
        "email": "baidjay@163.com"
      },
      "added": [

      ],
      "modified": [
        "Jenkinsfile"
      ],
      "removed": [

      ]
    },
    {
      "id": "cc36ed8cf920d9a3470fda6a28576ba7d29f9c04",
      "message": "ceshi ",
      "title": "ceshi ",
      "timestamp": "2022-03-30T08:52:13+00:00",
      "url": "http://192.168.205.128/root/devops-hello-world/-/commit/cc36ed8cf920d9a3470fda6a28576ba7d29f9c04",
      "author": {
        "name": "coolops",
        "email": "baidjay@163.com"
      },
      "added": [

      ],
      "modified": [
        "Jenkinsfile"
      ],
      "removed": [

      ]
    },
    {
      "id": "77e1901516fc2ee1a47b03bb4bfc63ca02e6b23d",
      "message": "多分支发布",
      "title": "多分支发布",
      "timestamp": "2022-03-30T08:45:11+00:00",
      "url": "http://192.168.205.128/root/devops-hello-world/-/commit/77e1901516fc2ee1a47b03bb4bfc63ca02e6b23d",
      "author": {
        "name": "coolops",
        "email": "baidjay@163.com"
      },
      "added": [

      ],
      "modified": [
        "Jenkinsfile"
      ],
      "removed": [

      ]
    }
  ],
  "total_commits_count": 3,
  "push_options": {
  },
  "repository": {
    "name": "Devops Hello World",
    "url": "git@192.168.205.128:root/devops-hello-world.git",
    "description": "",
    "homepage": "http://192.168.205.128/root/devops-hello-world",
    "git_http_url": "http://192.168.205.128/root/devops-hello-world.git",
    "git_ssh_url": "git@192.168.205.128:root/devops-hello-world.git",
    "visibility_level": 0
  }
}

需要什么就从Request中取什么。这样就可以通过WebHook触发一条Tekton流水线。

可以看到流水线正常运行了。

image.png

到目前为止,就可以实现代码提交到Gitlab,然后通过Webhook自动触发Tekton Pipeline了。

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