任务流引擎简介

Jenkinsfile (Declarative Pipeline)
pipeline {
    agent any 
    stages {
        stage('Build') { 
            steps {
                // 
            }
        }
        stage('Test') { 
            steps {
                // 
            }
        }
        stage('Deploy') { 
            steps {
                // 
            }
        }
    }
}

Jenkinsfile (Scripted Pipeline)
node {  
    stage('Build') { 
        // 
    }
    stage('Test') { 
        // 
    }
    stage('Deploy') { 
        // 
    }
}

name: default

kind: pipeline
type: docker

steps:
- name: backend
  image: golang
  commands:
    - go get
    - go build
    - go test

- name: frontend
  image: node:6
  commands:
    - npm install
    - npm test

- name: publish
  image: plugins/docker
  settings:
    repo: octocat/hello-world
    tags: [ 1, 1.1, latest ]
    registry: index.docker.io

- name: notify
  image: plugins/slack
  settings:
    channel: developers
    username: drone

start
for node in nodes:
    if all(node's dependency is done):
        do(node)
done 

if node's State is not start:
    start(node)
if node's State is not done:
    do(node's Next)

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: steps-
spec:
  entrypoint: hello-hello-hello

  # This spec contains two templates: hello-hello-hello and whalesay
  templates:
  - name: hello-hello-hello
    # Instead of just running a container
    # This template has a sequence of steps
    steps:
    - - name: hello1            # hello1 is run before the following steps
        template: whalesay
        arguments:
          parameters:
          - name: message
            value: "hello1"
    - - name: hello2a           # double dash => run after previous step
        template: whalesay
        arguments:
          parameters:
          - name: message
            value: "hello2a"
      - name: hello2b           # single dash => run in parallel with previous step
        template: whalesay
        arguments:
          parameters:
          - name: message
            value: "hello2b"

  # This is the same template as from the previous example
  - name: whalesay
    inputs:
      parameters:
      - name: message
    container:
      image: docker/whalesay
      command: [cowsay]
      args: ["{{inputs.parameters.message}}"]

tekton
tekton 来自Knative的build模块 做的事情和 argo 也大同小异，他扩展比较灵活，可以用来快速定制实现所需功能。tekton 的描述语法例子如下

apiVersion: tekton.dev/v1beta1
kind: Task
metadata:
  name: echo-hello-world
spec:
  steps:
    - name: echo
      image: ubuntu
      command:
        - echo
      args:
        - "Hello World"

const { events, Job } = require("brigadier");

events.on("simpleevent", (e, p) => {  // handler for a SimpleEvent
  var echo = new Job("echosimpleevent", "alpine:3.8");
  echo.tasks = [
    "echo Project " + p.name,
    "echo event type: $EVENT_TYPE",
    "echo payload " + JSON.stringify(e.payload)
  ];
  echo.env = {
    "EVENT_TYPE": e.type
  };
  echo.run();
});```

由于 kubernetes 对于部署和标准化环境的控制，以及 kubenetes 提供基础设施的强大能力，使得在 kubernetes 上实现类似的工具变得门槛很低，笔者也在早年也做过类似的 [玩具项目](https://github.com/arlert/kubepipe),
 看一下他的语法，是不是更 tekton/argo 有些相似呢。

```kubernetes
apiVersion: v1
kind: Pod
metadata:
  name: pod1
spec:
  restartPolicy: Never
  containers:
  - name: c
    image: alpine
    command: ["sh", "-c", "echo running pod1"]
---
apiVersion: v1
kind: Pod
metadata:
  name: pod2
spec:
  restartPolicy: Never
  containers:
  - name: c
    image: alpine
    command: ["sh", "-c", "echo running pod2"]
---
apiVersion: v1
kind: Pod
metadata:
  name: pod3
spec:
  restartPolicy: Never
  containers:
  - name: c
    image: alpine
    command: ["sh", "-c", "echo running pod3"]
---
apiVersion: v1
kind: Pipe
metadata:
  name: pipe
spec:
  stages:
  - name: stage1
    jobs: 
    - pod1
  - name: stage2
    jobs: 
    - pod2
  - name: stage3
    jobs: 
    - pod3