其他
开源 CI/CD 构建框架 TekTon 的深入剖析
简介
Tekton 是一个功能强大且灵活的 Kubernetes 原生 CI/CD 构建框架，用于创建持续集成和交付（CI/CD）系统。 关于 Tekton ，网上可以搜到很多很多介绍文档，本文主要阐述我对 Tekton 的实现原理和背后的技术逻辑的一点理解。
实现原理
高度抽象的结构化设计使得 Tekton 具有非常灵活的特性，那么 Tekton 是如何实现 workflow 的流转的呢？
Tekton 对 DAG 的支持相对比较简单。在 Tekton 中一个 Pipeline 就是一张 DAG ，Pipeline 中的多个Task可是DAG中的节点。Task 默认并发执行，可以通过 RunAfter 和 From 关键字控制执行顺序。
- name: lint-repo taskRef: name: pylint resources: inputs: - name: workspace resource: my-repo- name: test-app taskRef: name: make-test resources: inputs: - name: workspace resource: my-repo- name: build-app taskRef: name: kaniko-build-app runAfter: - test-app resources: inputs: - name: workspace resource: my-repo outputs: - name: image resource: my-app-image- name: build-frontend taskRef: name: kaniko-build-frontend runAfter: - test-app resources: inputs: - name: workspace resource: my-repo outputs: - name: image resource: my-frontend-image- name: deploy-all taskRef: name: deploy-kubectl resources: inputs: - name: my-app-image resource: my-app-image from: - build-app - name: my-frontend-image resource: my-frontend-image from: - build-frontend | | v v test-app lint-repo / \ v vbuild-app build-frontend \ / v v deploy-all* condition检查失败(exitCode != 0)，task不会被执行，pipelineRun状态不会因为condition检查失败而失败。* 多个条件之间 “与” 逻辑关系PipelineResource 在 Task 间数据交换
作为 CI/CD 的工具，代码在什么时候 Clone 到 WorkSpace 中，如何实现的？ Tekton 中抽象了 PipelineResource 进行任务之间的数据交换， GitResource 是其中最基础的一种。用法如下。
kind: PipelineResourcemetadata: name: skaffold-git-build-push-kanikospec: type: git params: - name: revision value: v0.32.0 - name: url value: https://github.com/GoogleContainerTools/skaffoldkind: Taskmetadata: name: build-push-kanikospec: inputs: resources: - name: workspace type: git steps: - name: build-and-push image: registry.cn-shanghai.aliyuncs.com/kaniko-project-edas/executor:v0.17.1Tekton 源自 Knative Build ，在 Knative Build 中使用 Init-container 来串联 Steps 保证 Steps 顺序执行，在上面的分析中我们知道 Tekton 是用 Containers 来执行 Steps ， Pod 的 Containers 是并行执行的， Tekton 是如何保证 Steps 执行顺序呢？
- args: - -wait_file - /tekton/tools/0 - -post_file - /tekton/tools/1 - -termination_path - /tekton/termination - -entrypoint - /ko-app/git-init - -- - -url - https://github.com/GoogleContainerTools/skaffold - -revision - v0.32.0 - -path - /workspace/workspace command: - /tekton/tools/entrypoint image: registry.cn-shanghai.aliyuncs.com/kaniko-project-edas/git-init:v0.10.2 name: step-git-source-skaffold-git-build-push-kaniko-rz765 - args: - -wait_file - /tekton/tools/1 - -post_file - /tekton/tools/2 - -termination_path - /tekton/termination - -entrypoint - /kaniko/executor - -- - --dockerfile=Dockerfile - --destination=localhost:5000/leeroy-web - --context=/workspace/workspace/examples/microservices/leeroy-web - --oci-layout-path=$(inputs.resources.builtImage.path) command: - /tekton/tools/entrypoint image: registry.cn-shanghai.aliyuncs.com/kaniko-project-edas/executor@sha256:565d31516f9bb91763dcf8e23ee161144fd4e27624b257674136c71559ce4493 name: step-build-and-push - args: - -wait_file - /tekton/tools/2 - -post_file - /tekton/tools/3 - -termination_path - /tekton/termination - -entrypoint - /ko-app/imagedigestexporter - -- - -images - '[{"name":"skaffold-image-leeroy-web-build-push-kaniko","type":"image","url":"localhost:5000/leeroy-web","digest":"","OutputImageDir":"/workspace/output/builtImage"}]' command: - /tekton/tools/entrypoint image: registry.cn-shanghai.aliyuncs.com/kaniko-project-edas/imagedigestexporter:v0.10.2 name: step-image-digest-exporter-lvlj9实践
使用 Tekton 构建代码并部署到 SAE
示例中的演示代码地址：https://github.com/alicloud-demo/spring-cloud-demoapiVersion: tekton.dev/v1alpha1kind: PipelineResourcemetadata: name: spring-cloud-demospec: type: git params: - name: url value: https://github.com/alicloud-demo/spring-cloud-demoapiVersion: tekton.dev/v1alpha1kind: Taskmetadata: name: build-deploy-saespec: inputs: resources: - name: source type: git steps: - name: build-and-deploy image: maven:3.3-jdk-8 command: ["mvn", "clean", "package", "-f", "source", "toolkit:deploy", "-Dtoolkit_profile=toolkit_profile.yaml", "-Dtoolkit_package=toolkit_package.yaml", "-Dtoolkit_deploy=toolkit_deploy.yaml"] securityContext: runAsUser: 0apiVersion: tekton.dev/v1alpha1kind: TaskRunmetadata: name: build-deploy-saespec: taskRef: name: build-deploy-sae inputs: resources: - name: source resourceRef: name: spring-cloud-demo5、导入到kubernetes中运行
kubectl apply -f source-2-service-taskrun.yamlkubectl logs build-deploy-sae-pod-85xdk step-build-and-deploy[INFO] Start to upload [provider3-1.0-SNAPSHOT.jar] using [Sae uploader].[INFO] [##################################################] 100.0%[INFO] Upload finished in 3341 ms, download url: [https://edas-hz.oss-cn-hangzhou.aliyuncs.com/apps/K8S_APP_ID/37adb12b-5f0c-4711-98ec-1f1e91e6b043/provider3-1.0-SNAPSHOT.jar][INFO] Begin to trace change order: e2499b9a-6a51-4904-819c-1838c1dd62cb[INFO] PipelineName: Batch: 1, PipelineId:f029314a-88bb-450b-aa35-7cc550ff1329[INFO] Waiting...[INFO] Waiting...[INFO] Waiting...[INFO] Waiting...[INFO] Waiting...[INFO] Waiting...[INFO] Waiting...[INFO] Waiting...[INFO] Deploy application successfully![INFO] ------------------------------------------------------------------------[INFO] BUILD SUCCESS[INFO] ------------------------------------------------------------------------[INFO] Total time: 32:41 min[INFO] Finished at: 2020-04-15T10:09:39+00:00[INFO] Final Memory: 47M/190M[INFO] ------------------------------------------------------------------------总结
区别于传统的 CI/CD 工具（Jenkins），Tekton 是一套构建 CICD 系统的框架。 Tekton 不能使你立即获得 CI/CD 的能力。但是基于 Tekton 可以设计出各种花式的构建部署流水线。得益于 Tekton 良好的抽象，这些设计出的流水线可以作为模板在多个组织，项目间共享。Tekton 源自 Knative 的 Build-Template 项目，设计之初的一个重要目标就是使人们能够共享和重用构成 pipeline 的组件，以及 Pipeline 本身。在 Tekton的RoadMap 中 Tekton Catelog 就是为了实现这一目标而提出的。
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