How-To: Share state between applications

Learn the strategies for sharing state between different applications

Dapr provides different ways to share state between applications.

Different architectures might have different needs when it comes to sharing state. In one scenario, you may want to:

  • Encapsulate all state within a given application
  • Have Dapr manage the access for you

In a different scenario, you may need two applications working on the same state to get and save the same keys.

To enable state sharing, Dapr supports the following key prefixes strategies:

Key prefixesDescription
appidThe default strategy allowing you to manage state only by the app with the specified appid. All state keys will be prefixed with the appid, and are scoped for the application.
nameUses the name of the state store component as the prefix. Multiple applications can share the same state for a given state store.
namespaceIf set, this setting prefixes the appid key with the configured namespace, resulting in a key that is scoped to a given namespace. This allows apps in different namespace with the same appid to reuse the same state store. If a namespace is not configured, the setting fallbacks to the appid strategy. For more information on namespaces in Dapr see How-To: Scope components to one or more applications
noneUses no prefixing. Multiple applications share state across different state stores.

Specifying a state prefix strategy

To specify a prefix strategy, add a metadata key named keyPrefix on a state component:

  1. apiVersion: dapr.io/v1alpha1
  2. kind: Component
  3. metadata:
  4.   name: statestore
  5.   namespace: production
  6. spec:
  7.   type: state.redis
  8.   version: v1
  9.   metadata:
  10.   - name: keyPrefix
  11.     value: <key-prefix-strategy>

Examples

The following examples demonstrate what state retrieval looks like with each of the supported prefix strategies.

appid (default)

In the example below, a Dapr application with app id myApp is saving state into a state store named redis:

  1. curl -X POST http://localhost:3500/v1.0/state/redis \
  2.   -H "Content-Type: application/json"
  3.   -d '[
  4.         {
  5.           "key": "darth",
  6.           "value": "nihilus"
  7.         }
  8.       ]'

The key will be saved as myApp||darth.

namespace

A Dapr application running in namespace production with app id myApp is saving state into a state store named redis:

  1. curl -X POST http://localhost:3500/v1.0/state/redis \
  2.   -H "Content-Type: application/json"
  3.   -d '[
  4.         {
  5.           "key": "darth",
  6.           "value": "nihilus"
  7.         }
  8.       ]'

The key will be saved as production.myApp||darth.

name

In the example below, a Dapr application with app id myApp is saving state into a state store named redis:

  1. curl -X POST http://localhost:3500/v1.0/state/redis \
  2.   -H "Content-Type: application/json"
  3.   -d '[
  4.         {
  5.           "key": "darth",
  6.           "value": "nihilus"
  7.         }
  8.       ]'

The key will be saved as redis||darth.

none

In the example below, a Dapr application with app id myApp is saving state into a state store named redis:

  1. curl -X POST http://localhost:3500/v1.0/state/redis \
  2.   -H "Content-Type: application/json"
  3.   -d '[
  4.         {
  5.           "key": "darth",
  6.           "value": "nihilus"
  7.         }
  8.       ]'

The key will be saved as darth.

Last modified July 6, 2022: [State Mgmt] Docset refresh (#2541) (a380dcbe)