---
type: docs
title: "Metadata API reference"
linkTitle: "Metadata API"
description: "Detailed documentation on the Metadata API"
weight: 800
---

Dapr has a metadata API that returns information about the sidecar allowing runtime discoverability. The metadata endpoint returns among other things, a list of the components loaded and the activated actors (if present).

The Dapr metadata API also allows you to store additional information in the format of key-value pairs.

Note: The Dapr metatada endpoint is for instance being used by the Dapr CLI when running dapr in standalone mode to store the PID of the process hosting the sidecar and the command used to run the application.

## Get the Dapr sidecar information

Gets the Dapr sidecar information provided by the Metadata Endpoint.

### HTTP Request

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

### URL Parameters

Parameter | Description
--------- | -----------
daprPort  | The Dapr port.

### HTTP Response Codes

Code | Description
---- | -----------
200  | Metadata information returned
500  | Dapr could not return the metadata information

### HTTP Response Body

**Metadata API Response Object**

Name                   | Type                                                                  | Description
----                   | ----                                                                  | -----------
id                     | string                                                                | Application ID
actors                 | [Metadata API Response Registered Actor](#metadataapiresponseactor)[] | A json encoded array of Registered Actors metadata.
extended.attributeName | string                                                                | List of custom attributes as key-value pairs, where key is the attribute name.
components             | [Metadata API Response Component](#metadataapiresponsecomponent)[]    | A json encoded array of loaded components metadata.

<a id="metadataapiresponseactor"></a>**Metadata API Response Registered Actor**

Name  | Type    | Description
----  | ----    | -----------
type  | string  | The registered actor type.
count | integer | Number of actors running.

<a id="metadataapiresponsecomponent"></a>**Metadata API Response Component**

Name    | Type   | Description
----    | ----   | -----------
name    | string | Name of the component.
type    | string | Component type.
version | string | Component version.

### Examples

Note: This example is based on the Actor sample provided in the [Dapr SDK for Python](https://github.com/dapr/python-sdk/tree/master/examples/demo_actor). 

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

```json
{
    "id":"demo-actor",
    "actors":[
        {
            "type":"DemoActor",
            "count":1
        }
    ],
    "extended": {
        "cliPID":"1031040",
        "appCommand":"uvicorn --port 3000 demo_actor_service:app"
    },
    "components":[
        {
            "name":"pubsub",
            "type":"pubsub.redis",
            "version":""
        },
        {
            "name":"statestore",
            "type":"state.redis",
            "version":""
        },
        {
            "name":"zipkin",
            "type":"exporters.zipkin",
            "version":""
        }
    ]
}
```

## Add a custom attribute to the Dapr sidecar information

Adds a custom attribute to the Dapr sidecar information stored by the Metadata Endpoint.

### HTTP Request

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

### URL Parameters

Parameter      | Description
---------      | -----------
daprPort       | The Dapr port.
attributeName  | Custom attribute name. This is they key name in the key-value pair.

### HTTP Request Body

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

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

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

```
attributeValue
```

### HTTP Response Codes

Code | Description
---- | -----------
204  | Custom attribute added to the metadata information

### Examples

Note: This example is based on the Actor sample provided in the [Dapr SDK for Python](https://github.com/dapr/python-sdk/tree/master/examples/demo_actor).

Add a custom attribute to the metadata endpoint:

```shell
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:

```json
{
    "id":"demo-actor",
    "actors":[
        {
            "type":"DemoActor",
            "count":1
        }
    ],
    "extended": {
        "myDemoAttribute": "myDemoAttributeValue",
        "cliPID":"1031040",
        "appCommand":"uvicorn --port 3000 demo_actor_service:app"
    },
    "components":[
        {
            "name":"pubsub",
            "type":"pubsub.redis",
            "version":""
        },
        {
            "name":"statestore",
            "type":"state.redis",
            "version":""
        },
        {
            "name":"zipkin",
            "type":"exporters.zipkin",
            "version":""
        }
    ]
}
```