Metadata API reference

Dapr has a metadata API that returns information about the sidecar allowing runtime discoverability. The metadata endpoint returns the following information.

• Runtime version
• List of the loaded resources (components, subscriptions and HttpEndpoints)
• Registered actor types
• Features enabled
• Application connection details
• Custom, ephemeral attributes with information.

Metadata API

组件

Each loaded component provides its name, type and version and also information about supported features in the form of component capabilities. These features are available for the state store and binding component types. The table below shows the component type and the list of capabilities for a given version. This list might grow in future and only represents the capabilities of the loaded components.

HTTPEndpoints

Each loaded HttpEndpoint provides a name to easily identify the Dapr resource associated with the runtime.

Subscriptions

The metadata API returns a list of pub/sub subscriptions that the app has registered with the Dapr runtime. This includes the pub/sub name, topic, routes, dead letter topic, and the metadata associated with the subscription.

Enabled features

A list of features enabled via Configuration spec (including build-time overrides).

App connection details

The metadata API returns information related to Dapr’s connection to the app. This includes the app port, protocol, host, max concurrency, along with health check details.

Attributes

The metadata API allows you to store additional attribute information in the format of key-value pairs. These are ephemeral in-memory and are not persisted if a sidecar is reloaded. This information should be added at the time of a sidecar creation (for example, after the application has started).

Get the Dapr sidecar information

Gets the Dapr sidecar information provided by the Metadata Endpoint.

使用案例：

The Get Metadata API can be used for discovering different capabilities supported by loaded components. It can help operators in determining which components to provision, for required capabilities.

HTTP Request

GET http://localhost:<daprPort>/v1.0/metadata

URL Parameters

HTTP Response Codes

HTTP Response Body

Metadata API Response Object

Metadata API Response Registered Actor

Metadata API Response Component

Metadata API Response HttpEndpoint

Metadata API Response Subscription

Metadata API Response Subscription Rules

Metadata API Response AppConnectionProperties

Metadata API Response AppConnectionProperties Health

示例

curl http://localhost:3500/v1.0/metadata

{
  "id": "myApp",
  "runtimeVersion": "1.12.0",
  "enabledFeatures": [
    "ServiceInvocationStreaming"
  ],
  "actors": [
    {
      "type": "DemoActor"
    }
  ],
  "components": [
    {
      "name": "pubsub",
      "type": "pubsub.redis",
      "version": "v1"
    },
    {
      "name": "statestore",
      "type": "state.redis",
      "version": "v1",
      "capabilities": [
        "ETAG",
        "TRANSACTIONAL",
        "ACTOR"
      ]
    }
  ],
  "httpEndpoints": [
    {
      "name": "my-backend-api"
    }
  ],
  "subscriptions": [
    {
      "pubsubname": "pubsub",
      "topic": "orders",
      "deadLetterTopic": "",
      "metadata": {
        "ttlInSeconds": "30"
      },
      "rules": [
          {
              "match": "%!s(<nil>)",
              "path": "orders"
          }
      ]
    }
  ],
  "extended": {
    "appCommand": "uvicorn --port 3000 demo_actor_service:app",
    "appPID": "98121",
    "cliPID": "98114",
    "daprRuntimeVersion": "1.12.0"
  },
  "appConnectionProperties": {
    "port": 3000,
    "protocol": "http",
    "channelAddress": "127.0.0.1",
    "health": {
      "healthProbeInterval": "5s",
      "healthProbeTimeout": "500ms",
      "healthThreshold": 3
    }
  }
}

Add a custom label to the Dapr sidecar information

Adds a custom label to the Dapr sidecar information stored by the Metadata endpoint.

使用案例：

The metadata endpoint is, for example, used by the Dapr CLI when running dapr in self hosted mode to store the PID of the process hosting the sidecar and store the command used to run the application. Applications can also add attributes as keys after startup.

HTTP Request

PUT http://localhost:<daprPort>/v1.0/metadata/attributeName

URL Parameters

HTTP Request Body

In the request you need to pass the custom attribute value as RAW data:

{
  "Content-Type": "text/plain"
}

Within the body of the request place the custom attribute value you want to store:

attributeValue

HTTP Response Codes

示例

Add a custom attribute to the metadata endpoint:

curl -X PUT -H "Content-Type: text/plain" --data "myDemoAttributeValue" http://localhost:3500/v1.0/metadata/myDemoAttribute

Get the metadata information to confirm your custom attribute was added:

{
  "id": "myApp",
  "runtimeVersion": "1.12.0",
  "enabledFeatures": [
    "ServiceInvocationStreaming"
  ],
  "actors": [
    {
      "type": "DemoActor"
    }
  ],
  "components": [
    {
      "name": "pubsub",
      "type": "pubsub.redis",
      "version": "v1"
    },
    {
      "name": "statestore",
      "type": "state.redis",
      "version": "v1",
      "capabilities": [
        "ETAG",
        "TRANSACTIONAL",
        "ACTOR"
      ]
    }
  ],
  "httpEndpoints": [
    {
      "name": "my-backend-api"
    }
  ],
  "subscriptions": [
    {
      "pubsubname": "pubsub",
      "topic": "orders",
      "deadLetterTopic": "",
      "metadata": {
        "ttlInSeconds": "30"
      },
      "rules": [
          {
              "match": "%!s(<nil>)",
              "path": "orders"
          }
      ]
    }
  ],
  "extended": {
    "myDemoAttribute": "myDemoAttributeValue",
    "appCommand": "uvicorn --port 3000 demo_actor_service:app",
    "appPID": "98121",
    "cliPID": "98114",
    "daprRuntimeVersion": "1.12.0"
  },
  "appConnectionProperties": {
    "port": 3000,
    "protocol": "http",
    "channelAddress": "127.0.0.1",
    "health": {
      "healthProbeInterval": "5s",
      "healthProbeTimeout": "500ms",
      "healthThreshold": 3
    }
  }
}