Tekton 的工作原理

$ k api-resources --api-group=tekton.dev
NAME                SHORTNAMES   APIGROUP     NAMESPACED   KIND
clustertasks                     tekton.dev   false        ClusterTask
conditions                       tekton.dev   true         Condition
pipelineresources                tekton.dev   true         PipelineResource
pipelineruns        pr,prs       tekton.dev   true         PipelineRun
pipelines                        tekton.dev   true         Pipeline
taskruns            tr,trs       tekton.dev   true         TaskRun
tasks                            tekton.dev   true         Task

// Node represents a Task in a pipeline.
type Node struct {
	// Task represent the PipelineTask in Pipeline
	Task Task
	// Prev represent all the Previous task Nodes for the current Task
	Prev []*Node
	// Next represent all the Next task Nodes for the current Task
	Next []*Node
}

// Graph represents the Pipeline Graph
type Graph struct {
	//Nodes represent map of PipelineTask name to Node in Pipeline Graph
	Nodes map[string]*Node
}

func Build(tasks Tasks) (*Graph, error) {
    ...
}

pipelineSpec = resources.ApplyParameters(pipelineSpec, pr)

func GetSchedulable(g *Graph, doneTasks ...string) (map[string]struct{}, error) {
    ...
}

spec:
  containers:
    - args:
      - -wait_file
      - /tekton/downward/ready
      - -wait_file_content
      - -post_file
      - /tekton/tools/0
      - -termination_path
      - /tekton/termination
      - -entrypoint
      - /ko-app/git-init
      - --
      - -url
      - ssh://git@gitlab.nip.io:8022/addozhang/logan-pulse.git
      - -revision
      - develop
      - -path
      - /workspace/git-source
      command:
      - /tekton/tools/entrypoint
      volumeMounts:
      - mountPath: /tekton/downward
        name: tekton-internal-downward
      
  volumes:
    - downwardAPI:
        defaultMode: 420
        items:
        - fieldRef:
            apiVersion: v1
            fieldPath: metadata.annotations['tekton.dev/ready']
          path: ready
      name: tekton-internal-downward

func orderContainers(entrypointImage string, steps []corev1.Container, results []v1alpha1.TaskResult) (corev1.Container, []corev1.Container, error) {
	initContainer := corev1.Container{
		Name:         "place-tools",
		Image:        entrypointImage,
		Command:      []string{"cp", "/ko-app/entrypoint", entrypointBinary},
		VolumeMounts: []corev1.VolumeMount{toolsMount},
	}

	if len(steps) == 0 {
		return corev1.Container{}, nil, errors.New("No steps specified")
	}

	for i, s := range steps {
		var argsForEntrypoint []string
		switch i {
		case 0:
			argsForEntrypoint = []string{
				// First step waits for the Downward volume file.
				"-wait_file", filepath.Join(downwardMountPoint, downwardMountReadyFile),
				"-wait_file_content", // Wait for file contents, not just an empty file.
				// Start next step.
				"-post_file", filepath.Join(mountPoint, fmt.Sprintf("%d", i)),
				"-termination_path", terminationPath,
			}
		default:
			// All other steps wait for previous file, write next file.
			argsForEntrypoint = []string{
				"-wait_file", filepath.Join(mountPoint, fmt.Sprintf("%d", i-1)),
				"-post_file", filepath.Join(mountPoint, fmt.Sprintf("%d", i)),
				"-termination_path", terminationPath,
			}
		}
    ...
}

workspaces:
- name: m2
  persistentVolumeClaim:
    claimName: m2-pv-claim

apiVersion: v1
kind: PersistentVolume
metadata:
  name: m2-pv
  labels:
    type: local
spec:
  storageClassName: manual
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteMany
  hostPath:
    path: "/data/.m2"
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: m2-pv-claim
spec:
  storageClassName: manual
  # volumeName: m2-pv
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 10Gi

workspaces:
- name: git-source
  volumeClaimTemplate:
    spec:
      accessModes:
      - ReadWriteMany
      resources:
        requests:
          storage: 1Gi

workspaces:
- name: temp
  emptyDir: {}

workspaces:
- name: maven-settings
  configmap:
    name: maven-settings

apiVersion: tekton.dev/v1beta1
kind: Task
metadata:
  name: print-date
  annotations:
    description: |
            A simple task that prints the date
spec:
  results:
    - name: current-date-unix-timestamp
      description: The current date in unix timestamp format
    - name: current-date-human-readable
      description: The current date in human readable format
  steps:
    - name: print-date-unix-timestamp
      image: bash:latest
      script: |
        #!/usr/bin/env bash
        date +%s | tee $(results.current-date-unix-timestamp.path)        
    - name: print-date-humman-readable
      image: bash:latest
      script: |
        #!/usr/bin/env bash
        date | tee $(results.current-date-human-readable.path)        
---
apiVersion: tekton.dev/v1beta1
kind: PipelineRun
metadata:
  name: pass-date
spec:
  pipelineSpec:
    tasks:
      - name: print-date
        taskRef:
          name: print-date
      - name: read-date
        runAfter: #配置执行顺序
          - print-date
        taskSpec:
          params:
            - name: current-date-unix-timestamp
              type: string
            - name: current-date-human-readable
              type: string
          steps:
            - name: read
              image: busybox
              script: |
                echo $(params.current-date-unix-timestamp)
                echo $(params.current-date-human-readable)                
        params:
          - name: current-date-unix-timestamp
            value: $(tasks.print-date.results.current-date-unix-timestamp) # 注入参数
          - name: current-date-human-readable
            value: $(tasks.print-date.results.current-date-human-readable) # 注入参数