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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