Targets

Named policies are applied to targets. Dapr supports three target types that apply all Dapr building block APIs:

• components
• actors

Apps

With the apps target, you can apply retry, timeout, and circuitBreaker policies to service invocation calls between Dapr apps. Under targets/apps, policies are applied to each target service’s app-id. The policies are invoked when a failure occurs in communication between sidecars, as shown in the diagram below.

Example of policies to a target app with the app-id “appB”:

Components

With the target, you can apply retry, timeout and circuitBreaker policies to component operations.

Outbound

outbound operations are calls from the sidecar to a component, such as:

• Persisting or retrieving state.
• Publishing a message on a PubSub component.

Inbound

inbound operations are calls from the sidecar to your application, such as:

• PubSub subscriptions when delivering a message.
• Input bindings.

PubSub

Actors

With the target, you can apply retry, timeout, and circuitBreaker policies to actor operations.

When using a circuitBreaker policy for the actors target, you can specify how circuit breaking state should be scoped by using circuitBreakerScope:

• id: an individual actor ID
• type: all actors of a given actor type
• both: both of the above

You can also specify a cache size for the number of circuit breakers to keep in memory with the circuitBreakerCacheSize property, providing an integer value, e.g. .

Example

Try out one of the Resiliency quickstarts: