Configure Retries, Restarts, and Replays in Subflows

为流程配置正确的重试行为,可以让失败的子流程执行从合适的位置继续,避免重复运行已经成功的任务。

使用子流程时,需要区分 Subflow 任务级别的重试,以及子流程内部流程级别的重试。本指南说明如何管理子流程执行的重试、重启和重放,避免不必要地再次执行已完成任务。

流程级重试与子流程任务级重试

Subflow 任务级重试

在 Subflow 任务上定义 retry,控制的是父流程如何重试这个 Subflow 任务本身。例如:

id: parent_flow
namespace: company.team

tasks:
  - id: subflow
    type: io.kestra.plugin.core.flow.Subflow
    namespace: company.team
    flowId: my_subflow
    wait: true
    retry:
      type: constant
      maxAttempts: 3
      interval: PT1S

这里的重试应用在父流程中的 Subflow 任务上。任务失败时,整个子流程执行会从头再试。因此,每次重试执行都会重新运行子流程中的全部任务,包括已经成功的任务。

子流程内部的流程级重试

如果希望从子流程中失败的任务继续执行,而不再次运行已经成功的任务,应把 retry 配置在子流程的流程定义中,而不是 Subflow 任务上。这样子流程执行可以从失败任务重新开始,而不是从整个流程的开头开始。

例如:

id: my_subflow
namespace: company.team

retry:
  maxAttempts: 3
  behavior: RETRY_FAILED_TASK
  type: constant
  interval: PT1S

tasks:
  - id: start
    type: io.kestra.plugin.core.log.Log
    message: This task will succeed and won't be retried

  - id: fail
    type: io.kestra.plugin.core.execution.Fail
    runIf: "{{ randomInt(lower=0, upper=2) == 1 }}"
    errorMessage: Bad value returned!

  - id: end
    type: io.kestra.plugin.core.log.Log
    message: This task will only run if the fail task succeeds

这个流程失败时,只会重试失败的任务——本例中的 fail。已经成功的 start 不会再运行。

示例的 runIf 使用随机整数模拟失败。它用于观察执行机制,不能保证每次都失败或在固定尝试次数内成功;本稿未执行该流程。

推荐配置

大多数情况下,应当:

  • 在子流程内部的流程级别定义 retry,不要配置在 Subflow 任务上。
  • 使用 behavior: RETRY_FAILED_TASK,从失败任务继续,避免重新运行已经成功的任务。
  • 只有希望每次都从开头重新启动子流程执行时,才使用 behavior: CREATE_NEW_EXECUTION。

示例:父流程调用子流程

id: my_parent_flow
namespace: company.team

tasks:
  - id: subflow
    type: io.kestra.plugin.core.flow.Subflow
    namespace: company.team
    flowId: my_subflow
    wait: true

  - id: hello
    type: io.kestra.plugin.core.log.Log
    message: Success

当 my_subflow 配置了 behavior: RETRY_FAILED_TASK,重试时就会自动从失败任务重新开始。父流程不需要额外配置。

重放与重启

  • 重放(Replay):如果子流程定义了 behavior: RETRY_FAILED_TASK,可以从失败的子流程任务处重放父执行。
  • 重启(Restart):通过 UI 或 API 重启一个子流程任务失败的父执行时,默认会从头重启整个子执行,不受子流程任务定义影响;只有子流程 YAML 在流程级重试配置中定义 behavior: RETRY_FAILED_TASK 时,才不采用这种从头重启行为。

要点

  • 需要细粒度控制重启位置时,在子流程内部使用流程级重试。
  • 用 behavior: RETRY_FAILED_TASK 从失败任务继续。
  • 避免父流程与子流程配置相互冲突的重试行为。
  • 只有希望每次重试都创建一个全新的子流程执行时,才使用子流程任务级重试。只要 retry 定义在 Subflow 任务级别,每次重试就会从开头创建新执行,不会从现有子执行中的失败任务继续;即使子流程流程级别配置了其他 behavior,这一点也不会改变。

来源:Subflow Retries, Restarts, and Replays in Kestra | Kestra。原文作者:Kestra 文档贡献者 / Kestra Technologies。许可:Apache-2.0。中文内容和版式作了调整。

Copyright 2019 Kestra Technologies.

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