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Overview

The Retry is a fundamental concept in the Serverless Workflow DSL, used to define the strategy for retrying a failed task when an error is encountered during execution. This policy provides developers with fine-grained control over how and when to retry failed tasks, enabling robust error handling and fault tolerance within workflows.

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Retry Policy

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when
string
A runtime expression used to determine whether or not to retry running the task, in a given context.
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exceptWhen
string
A runtime expression used to determine whether or not to retry running the task, in a given context.
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delay
duration
The duration, if any, to wait between retry attempts.
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limit
object
The limits, if any, to impose to the retry policy.
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backoff
object
The backoff strategy to use, if any.
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jitter
object
The parameters, if any, that control the randomness or variability of the delay between retry attempts.

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Retry Limit

The definition of retry limits.
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attempt.count
integer
The maximum attempts count.
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attempt.duration
duration
The duration limit, if any, for all retry attempts.
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duration
duration
The maximum duration, if any, during which to retry a given task.

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Backoff Strategies

The definition of a retry backoff strategy.
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constant
object
The definition of the constant backoff to use, if any.Required if exponential and linear are not set, otherwise ignored.
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exponential
object
The definition of the exponential backoff to use, if any.Required if constant and linear are not set, otherwise ignored.
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linear
object
The definition of the linear backoff to use, if any.Required if constant and exponential are not set, otherwise ignored.

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Jitter

Represents the definition of the parameters that control the randomness or variability of a delay, typically between retry attempts.
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from
duration
required
The minimum duration of the jitter range.
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to
duration
required
The maximum duration of the jitter range.

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Examples

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Exponential Backoff with Retry Limit

document:
  dsl: '1.0.3'
  namespace: test
  name: retry-example
  version: '0.1.0'
do:
  - callExternalService:
      try:
        - makeRequest:
            call: http
            with:
              method: get
              endpoint: https://api.example.com/data
      catch:
        errors:
          with:
            type: https://serverlessworkflow.io/spec/1.0.0/errors/communication
        retry:
          delay:
            seconds: 3
          backoff:
            exponential: {}
          limit:
            attempt:
              count: 5

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Retry with Jitter

retry:
  delay:
    seconds: 1
  backoff:
    exponential: {}
  jitter:
    from:
      milliseconds: 100
    to:
      milliseconds: 500
  limit:
    attempt:
      count: 3

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Linear Backoff

retry:
  delay:
    seconds: 2
  backoff:
    linear: {}
  limit:
    attempt:
      count: 5
    duration:
      minutes: 5

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Constant Backoff with Duration Limit

retry:
  delay:
    seconds: 5
  backoff:
    constant: {}
  limit:
    duration:
      minutes: 10

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Conditional Retry

retry:
  when: .error.status >= 500
  delay:
    seconds: 2
  backoff:
    exponential: {}
  limit:
    attempt:
      count: 3

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Retry with Exception Condition

retry:
  exceptWhen: .error.status == 401
  delay:
    seconds: 1
  backoff:
    exponential: {}
  limit:
    attempt:
      count: 5

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Reusable Retry Policies

You can define retry policies in the workflow’s reusable components and reference them by name: 
document:
  dsl: '1.0.3'
  namespace: test
  name: reusable-retry-example
  version: '0.1.0'
use:
  retries:
    standardRetry:
      delay:
        seconds: 3
      backoff:
        exponential: {}
      limit:
        attempt:
          count: 5
do:
  - callService:
      try:
        - makeRequest:
            call: http
            with:
              method: get
              endpoint: https://api.example.com/data
      catch:
        errors:
          with:
            type: https://serverlessworkflow.io/spec/1.0.0/errors/communication
        retry: standardRetry

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Duration Format

Durations can be defined through properties or with an ISO 8601 string:

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Using Properties

delay:
  hours: 2
  minutes: 15
  seconds: 30

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Using ISO 8601 String

delay: PT2H15M30S

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Duration Properties

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days
integer
Number of days, if any.
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hours
integer
Number of hours, if any.
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minutes
integer
Number of minutes, if any.
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seconds
integer
Number of seconds, if any.
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milliseconds
integer
Number of milliseconds, if any.

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