本篇介绍一下 ArgoWorkflow 中的 ExitHandler 和 LifecycleHook 功能，可以根据流水线每一步的不同状态，执行不同操作，一般用于发送通知.

1. 概述

本篇介绍一下 ArgoWorkflow 中的 ExitHandler 和 LifecycleHook 功能，可以根据流水线每一步的不同状态，执行不同操作，一般用于发送通知.

比如当某个步骤，或者某个 Workflow 执行失败时，发送邮件通知.

在 ArgoWorkflow 不同版本中中有两种实现方式:

• 1）v2.7 版本开始提供了 exit handler 功能，可以指定一个在流水线运行完成后执行的模板。同时这个模板中还可以使用 when 字段来做条件配置，以实现比根据当前流水线运行结果来执行不同流程。
  • 已废弃，v3.3 版本后不推荐使用
• 2）v.3.3 版本新增 LifecycleHook，exit handler 功能则不推荐使用了，LifecycleHook 提供了更细粒度以及更多功能，exit handler 可以看做是一个简单的 LifecycleHook。

2. ExitHandler

虽然官方已经不推荐使用该功能了，但是还是简单介绍一下.

ArgoWorkflow 提供了 spec.onExit 字段，可以指定一个 template，当 workflow 执行后(不论成功或者失败)就会运行 onExit 指定的 template.

类似于 Tekton 中的 finally 字段 。

同时这个 template 中可以使用 when 字段来做条件配置。比如根据当前流水线运行结果来执行不同流程.

比如下面这个 Demo,完整 Workflow 内容如下:

# An exit handler is a template reference that executes at the end of the workflow
# irrespective of the success, failure, or error of the primary workflow. To specify
# an exit handler, reference the name of a template in 'spec.onExit'.
# Some common use cases of exit handlers are:
# - sending notifications of workflow status (e.g. e-mail/slack)
# - posting the pass/fail status to a webhook result (e.g. github build result)
# - cleaning up workflow artifacts
# - resubmitting or submitting another workflow
apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: exit-handlers-
spec:
  entrypoint: intentional-fail
  onExit: exit-handler
  templates:
    # primary workflow template
    - name: intentional-fail
      container:
        image: alpine:latest
        command: [sh, -c]
        args: ["echo intentional failure; exit 1"]

    # exit handler related templates
    # After the completion of the entrypoint template, the status of the
    # workflow is made available in the global variable {{workflow.status}}.
    # {{workflow.status}} will be one of: Succeeded, Failed, Error
    - name: exit-handler
      steps:
        - - name: notify
            template: send-email
          - name: celebrate
            template: celebrate
            when: "{{workflow.status}} == Succeeded"
          - name: cry
            template: cry
            when: "{{workflow.status}} != Succeeded"
    - name: send-email
      container:
        image: alpine:latest
        command: [sh, -c]
        # Tip: {{workflow.failures}} is a JSON list. If you're using bash to read it, we recommend using jq to manipulate
        # it. For example:
        #
        # echo "{{workflow.failures}}" | jq -r '.[] | "Failed Step: \(.displayName)\tMessage: \(.message)"'
        #
        # Will print a list of all the failed steps and their messages. For more info look up the jq docs.
        # Note: jq is not installed by default on the "alpine:latest" image, however it can be installed with "apk add jq"
        args: ["echo send e-mail: {{workflow.name}} {{workflow.status}} {{workflow.duration}}. Failed steps {{workflow.failures}}"]
    - name: celebrate
      container:
        image: alpine:latest
        command: [sh, -c]
        args: ["echo hooray!"]
    - name: cry
      container:
        image: alpine:latest
        command: [sh, -c]
        args: ["echo boohoo!"]

首先是通过 spec.onExit 字段配置了一个 template 。

spec:
  entrypoint: intentional-fail
  onExit: exit-handler

这个 template 内容如下:

    - name: exit-handler
      steps:
        - - name: notify
            template: send-email
          - name: celebrate
            template: celebrate
            when: "{{workflow.status}} == Succeeded"
          - name: cry
            template: cry
            when: "{{workflow.status}} != Succeeded"

内部包含 3 个步骤，每个步骤又是一个 template:

• 1）发送邮件，无论成功或者失败
• 2）若成功则执行 celebrate
• 3）若失败则执行 cry

该 Workflow 不论执行结果如何，都会发送邮件，邮件内容包含了任务的执行信息，若是执行成功则会额外打印执行成功，若是执行失败则会打印执行失败.

为了简单，这里所有操作都使用 echo 命令进行模拟 。

由于在主 template 中最后执行的是 exit 1 命令，因此会判断为执行失败，会发送邮件并打印失败信息，Pod 列表如下:

[root@argo-1 lifecyclehook]# k get po
NAME                                              READY   STATUS      RESTARTS        AGE
exit-handlers-44ltf                               0/2     Error       0               2m45s
exit-handlers-44ltf-cry-1621717811                0/2     Completed   0               2m15s
exit-handlers-44ltf-send-email-2605424148         0/2     Completed   0               2m15s

各个 Pod 日志 。

[root@argo-1 lifecyclehook]# k logs -f exit-handlers-44ltf-cry-1621717811
boohoo!
time="2024-05-25T11:34:39.472Z" level=info msg="sub-process exited" argo=true error="<nil>"
[root@argo-1 lifecyclehook]# k logs -f exit-handlers-44ltf-send-email-2605424148
send e-mail: exit-handlers-44ltf Failed 30.435347. Failed steps [{"displayName":"exit-handlers-44ltf","message":"Error (exit code 1)","templateName":"intentional-fail","phase":"Failed","podName":"exit-handlers-44ltf","finishedAt":"2024-05-25T11:34:16Z"}]
time="2024-05-25T11:34:44.424Z" level=info msg="sub-process exited" argo=true error="<nil>"
[root@argo-1 lifecyclehook]# k logs -f exit-handlers-44ltf
intentional failure
time="2024-05-25T11:34:15.856Z" level=info msg="sub-process exited" argo=true error="<nil>"
Error: exit status 1

至此，这个 exitHandler 功能就可以满足我们基本的通知需求了，比如将结果以邮件发出，或者对接外部系统 Webhook，更加复杂的需求也可以实现.

不过存在一个问题，就是 exitHandler 是 Workflow 级别的，只能整个 Workflow 执行完成才会执行 exitHandler.

如果想要更细粒度的，比如 template 级别则做不到，v3.3 中提供的 LifecycleHook 则实现了更加细粒度的通知.

3. LifecycleHook

LifecycleHook 可以看做是一个比较灵活的 exit hander，官方描述如下:

Put differently, an exit handler is like a workflow-level LifecycleHook with an expression of workflow.status == "Succeeded" or workflow.status == "Failed" or workflow.status == "Error". 。

LifecycleHook 有两种级别:

• Workflow 级别
• template 级别

Workflow 级别

Workflow 级别的 LifecycleHook 和 exitHandler 基本类似.

下面就是一个 Workflow 级别的 LifecycleHook Demo，完整 Workflow 内容如下:

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: lifecycle-hook-
spec:
  entrypoint: main
  hooks:
    exit: # Exit handler
      template: http
    running:
      expression: workflow.status == "Running"
      template: http
  templates:
    - name: main
      steps:
      - - name: step1
          template: heads
    
    - name: heads
      container:
        image: alpine:3.6
        command: [sh, -c]
        args: ["echo \"it was heads\""]
    
    - name: http
      http:
        # url: http://dummy.restapiexample.com/api/v1/employees
        url: "https://raw.githubusercontent.com/argoproj/argo-workflows/4e450e250168e6b4d51a126b784e90b11a0162bc/pkg/apis/workflow/v1alpha1/generated.swagger.json"

首先是配置 hook 。

spec:
  entrypoint: main
  hooks:
    exit: # Exit handler
      template: http
    running:
      expression: workflow.status == "Running"
      template: http

可以看到，原有的 onExit 被 hooks 字段替代了，同时 hooks 字段支持指定多个 hook，每个 hook 中可以通过 expression 设置不同的条件，只有满足条件时才会执行.

这里的 template 则是一个内置的 http 类型的 template 。

    - name: http
      http:
        # url: http://dummy.restapiexample.com/api/v1/employees
        url: "https://raw.githubusercontent.com/argoproj/argo-workflows/4e450e250168e6b4d51a126b784e90b11a0162bc/pkg/apis/workflow/v1alpha1/generated.swagger.json"

该 Workflow 的主 template 比较简单，就是使用 echo 命令打印一句话，因此会执行成功，那么 hooks 中的两个 hooks 都会执行.

两个 hook 对应的都是同一个 template，因此会执行两遍.

template 级别

template 级别的 hooks 则是提供了更细粒度的配置，比如可能用户比较关心 Workflow 中某一个步骤的状态，可以单独为该 template 设置 hook.

下面是一个template 级别的 hooks demo，Workflow 完整内容如下:

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: lifecycle-hook-tmpl-level-
spec:
  entrypoint: main
  templates:
    - name: main
      steps:
        - - name: step-1
            hooks:
              running: # Name of hook does not matter
                # Expr will not support `-` on variable name. Variable should wrap with `[]`
                expression: steps["step-1"].status == "Running"
                template: http
              success:
                expression: steps["step-1"].status == "Succeeded"
                template: http
            template: echo
        - - name: step2
            hooks:
              running:
                expression: steps.step2.status == "Running"
                template: http
              success:
                expression: steps.step2.status == "Succeeded"
                template: http
            template: echo

    - name: echo
      container:
        image: alpine:3.6
        command: [sh, -c]
        args: ["echo \"it was heads\""]

    - name: http
      http:
        # url: http://dummy.restapiexample.com/api/v1/employees
        url: "https://raw.githubusercontent.com/argoproj/argo-workflows/4e450e250168e6b4d51a126b784e90b11a0162bc/pkg/apis/workflow/v1alpha1/generated.swagger.json"

内容和 Workflow 级别的 Demo 差不多，只是 hooks 字段的位置不同 。

spec:
  entrypoint: main
  templates:
    - name: main
      steps:
        - - name: step-1
            hooks:
              # ...
            template: echo
        - - name: step2
            hooks:
						  # ...
            template: echo

在 spec.templates 中我们分别为不同的步骤配置了 hooks，相比与 exiHandler 则更加灵活.

如何替代 exitHandler

LifecycleHook 可以完美替代 Exit Handler，就是把 Hook 命名为 exit，虽然 hook 的命名无无关紧要，但是如果是 exit 则是会特殊处理.

官方原文如下:

You must not name a LifecycleHook exit or it becomes an exit handler; otherwise the hook name has no relevance. 。

这个 exit 直接是写死在代码里的，具体如下:

const (
    ExitLifecycleEvent = "exit"
)

func (lchs LifecycleHooks) GetExitHook() *LifecycleHook {
    hook, ok := lchs[ExitLifecycleEvent]
    if ok {
       return &hook
    }
    return nil
}

func (lchs LifecycleHooks) HasExitHook() bool {
    return lchs.GetExitHook() != nil
}

那么我们只需要将 LifecycleHook 命名为 exit 即可替代 exit handler，就像这样:

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: lifecycle-hook-
spec:
  entrypoint: main
  hooks:
    exit: # if named exit, it'a an Exit handler
      template: http
  templates:
    - name: main
      steps:
      - - name: step1
          template: heads
    - name: http
      http:
        # url: http://dummy.restapiexample.com/api/v1/employees
        url: "https://raw.githubusercontent.com/argoproj/argo-workflows/4e450e250168e6b4d51a126b784e90b11a0162bc/pkg/apis/workflow/v1alpha1/generated.swagger.json"

4. 常见通知模板

通知一般支持 webhook、email、slack、微信通知等方式.

在 ArgoWorkflow 中则是准备对应的模板即可.

Webhook

这应该是最通用的一种方式，收到消息后具体做什么事情，可以灵活的在 webhook 服务调整.

对于 ArgoWorkflow 模板就是执行 curl 命令即可，因此只需要一个包含 curl 工具的容器 。

apiVersion: argoproj.io/v1alpha1
kind: ClusterWorkflowTemplate
metadata:
  name: step-notify-webhook
spec:
  templates:
    - name: webhook
      inputs:
        parameters:
          - name: POSITIONS # 指定什么时候运行，多个以逗号隔开，例如：Pending,Running,Succeeded,Failed,Error
            value: "Succeeded,Failed,Error"
          - name: WEBHOOK_ENDPOINT
          - name: CURL_VERSION
            default: "8.4.0"

      container:
        image: curlimages/curl:{{inputs.parameters.CURL_VERSION}}
        command: [sh, -cx]
        args: [
          "curl -X POST  -H \"Content-type: application/json\" -d '{
          \"message\": \"{{workflow.name}} {{workflow.status}}\",
          \"workflow\": {
                \"name\": \"{{workflow.name}}\",
                \"namespace\": \"{{workflow.namespace}}\",
                \"uid\": \"{{workflow.uid}}\",
                \"creationTimestamp\": \"{{workflow.creationTimestamp}}\",
                \"status\": \"{{workflow.status}}\"
              }
        }'
        {{inputs.parameters.WEBHOOK_ENDPOINT}}"
        ]

Email

对于邮件方式，这里简单提供一个使用 Python 发送邮件的 Demo.

# use golangcd-lint for lint
apiVersion: argoproj.io/v1alpha1
kind: ClusterWorkflowTemplate
metadata:
  name: step-notify-email
spec:
  templates:
    - name: email
      inputs:
        parameters:
          - name: POSITIONS # 指定什么时候运行，多个以逗号隔开，例如：Pending,Running,Succeeded,Failed,Error
            value: "Succeeded,Failed,Error"
          - name: CREDENTIALS_SECRET
          - name: TO # 收件人邮箱
          - name: PYTHON_VERSION
            default: "3.8-alpine"
      script:
        image: docker.io/library/python:{{inputs.parameters.PYTHON_VERSION}}
        command: [ python ]
        env:
          - name: TO
            value: '{{inputs.parameters.TO}}'
          - name: HOST
            valueFrom:
              secretKeyRef:
                name: '{{inputs.parameters.CREDENTIALS_SECRET}}'
                key: host
          - name: PORT
            valueFrom:
              secretKeyRef:
                name: '{{inputs.parameters.CREDENTIALS_SECRET}}'
                key: port
          - name: FROM
            valueFrom:
              secretKeyRef:
                name: '{{inputs.parameters.CREDENTIALS_SECRET}}'
                key: from
          - name: USERNAME
            valueFrom:
              secretKeyRef:
                name: '{{inputs.parameters.CREDENTIALS_SECRET}}'
                key: username
          - name: PASSWORD
            valueFrom:
              secretKeyRef:
                name: '{{inputs.parameters.CREDENTIALS_SECRET}}'
                key: password
          - name: TLS
            valueFrom:
              secretKeyRef:
                name: '{{inputs.parameters.CREDENTIALS_SECRET}}'
                key: tls
        source: |
          import smtplib
          import ssl
          import os
          from email.header import Header
          from email.mime.text import MIMEText

          smtp_server = os.getenv('HOST')
          port = os.getenv('PORT')
          sender_email = os.getenv('FROM')
          receiver_emails = os.getenv('TO')
          user = os.getenv('USERNAME')
          password = os.getenv('PASSWORD')
          tls = os.getenv('TLS')

          # 邮件正文,文本格式
          # 构建邮件消息
          workflow_info = f"""\
            "workflow": {{
              "name": "{{workflow.name}}",
              "namespace": "{{workflow.namespace}}",
              "uid": "{{workflow.uid}}",
              "creationTimestamp": "{{workflow.creationTimestamp}}",
              "status": "{{workflow.status}}"
            }}
          """
          msg = MIMEText(workflow_info, 'plain', 'utf-8')
          # 邮件头信息
          msg['From'] = Header(sender_email)  # 发送者
          msg['To'] = Header(receiver_emails)  # 接收者
          subject = '{{workflow.name}} {{workflow.status}}'
          msg['Subject'] = Header(subject, 'utf-8')  # 邮件主题
          if tls == 'True':
            context = ssl.create_default_context()
            server = smtplib.SMTP_SSL(smtp_server, port, context=context)
          else:
            server = smtplib.SMTP(smtp_server, port)

          if password != '':
            server.login(user, password)

          for receiver in [item for item in receiver_emails.split(' ') if item]:
            server.sendmail(sender_email, receiver, msg.as_string())

            server.quit()

---

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5. 小结

本文主要分析了 Argo 中的通知触发机制，包括旧版的 exitHandler 以及新版的 LifecycleHook，并提供了几个简单的通知模板.

最后则是推荐使用更加灵活的 LifecycleHook.

最后此篇关于ArgoWorkflow教程(八)---基于LifecycleHook实现流水线通知提醒的文章就讲到这里了,如果你想了解更多关于ArgoWorkflow教程(八)---基于LifecycleHook实现流水线通知提醒的内容请搜索CFSDN的文章或继续浏览相关文章，希望大家以后支持我的博客！ 。