Overview

Dapr provides a capability for defining and applying fault tolerance resiliency policies via a resiliency spec. Resiliency specs are saved in the same location as components specs and are applied when the Dapr sidecar starts. The sidecar determines how to apply resiliency policies to your Dapr API calls. In self-hosted mode, the resiliency spec must be named . In Kubernetes Dapr finds the named resiliency specs used by your application. Within the resiliency spec, you can define policies for popular resiliency patterns, such as:

Additionally, resiliency policies can be .

  1. apiVersion: dapr.io/v1alpha1
  2. kind: Resiliency
  3. metadata:
  4.   name: myresiliency
  5. # similar to subscription and configuration specs, scopes lists the Dapr App IDs that this
  6. # resiliency spec can be used by.
  7. scopes:
  8.   - app1
  9.   - app2
  10. spec:
  11.   # policies is where timeouts, retries and circuit breaker policies are defined. 
  12.   # each is given a name so they can be referred to from the targets section in the resiliency spec.
  13.   policies:
  14.     # timeouts are simple named durations.
  15.     timeouts:
  16.       general: 5s
  17.       important: 60s
  18.       largeResponse: 10s
  20.     # retries are named templates for retry configurations and are instantiated for life of the operation.
  21.     retries:
  22.       pubsubRetry:
  23.         policy: constant
  24.         duration: 5s
  25.         maxRetries: 10
  27.       retryForever:
  28.         policy: exponential
  29.         maxRetries: -1 # retry indefinitely
  31.       important:
  32.         policy: constant
  34.         maxRetries: 30
  36.       someOperation:
  37.         policy: exponential
  38.         maxInterval: 15s
  40.       largeResponse:
  41.         policy: constant
  42.         duration: 5s
  43.         maxRetries: 3
  45.     # circuit breakers are automatically instantiated per component and app instance.
  46.     # circuit breakers maintain counters that live as long as the Dapr sidecar is running. They are not persisted.
  47.     circuitBreakers:
  48.       simpleCB:
  49.         maxRequests: 1
  50.         timeout: 30s 
  51.         trip: consecutiveFailures >= 5
  53.       pubsubCB:
  54.         maxRequests: 1
  55.         interval: 8s
  56.         timeout: 45s
  57.         trip: consecutiveFailures > 8
  59.   # targets are what named policies are applied to. Dapr supports 3 target types - apps, components and actors
  60.   targets:
  61.     apps:
  62.       appB:
  63.         timeout: general
  64.         retry: important
  65.         # circuit breakers for services are scoped app instance.
  68.     actors:
  69.       myActorType: # custom Actor Type Name
  70.         timeout: general
  71.         retry: important
  72.         # circuit breakers for actors are scoped by type, id, or both.
  73.         # when a breaker is tripped, that type or id is removed from the placement table for the configured `timeout` duration.
  74.         circuitBreaker: simpleCB
  75.         circuitBreakerScope: both ## 
  76.         circuitBreakerCacheSize: 5000
  78.     components:
  79.       # for state stores, policies apply to saving and retrieving state.
  80.       statestore1: # any component name -- happens to be a state store here
  81.         outbound:
  82.           timeout: general
  83.           retry: retryForever
  84.           # circuit breakers for components are scoped per component configuration/instance. For example myRediscomponent.
  85.           # when this breaker is tripped, all interaction to that component is prevented for the configured `timeout` duration.
  86.           circuitBreaker: simpleCB
  88.       pubsub1: # any component name -- happens to be a pubsub broker here
  89.         outbound:
  90.           retry: pubsubRetry
  91.           circuitBreaker: pubsubCB
  93.       pubsub2: # any component name -- happens to be another pubsub broker here
  94.         outbound:
  95.           retry: pubsubRetry
  96.           circuitBreaker: pubsubCB
  97.         inbound: # inbound only applies to delivery from sidecar to app
  98.           timeout: general
  99.           retry: important

Watch this video for how to use resiliency:

Next steps