REST API

EMQX exposes an HTTP management API designed following OpenAPI (Swagger) 3.0 specification.

After EMQX is started, you can visit http://localhost:18083/api-docs/index.html to view the API document and execute the management APIs from the Swagger UI. By default, under the Dashboard configuration, swagger_support is set to true, indicating Swagger UI support is enabled, which means all Swagger-related features are turned on, such as generating interactive API documentation. You can also set it to false to disable this feature. For more information, see Dashboard configuration.

The section introduces how to work with EMQX REST API.

Basic Path

EMQX has version control on the REST API, all API paths from EMQX 5.0.0 start with /api/v5.

Authentication

EMQX's REST API uses HTTP Basic Authentication with API keys as authentication credentials. Before using the EMQX REST API, you need to create an API key.

TIP

For security reasons, from EMQX 5.0.0 onwards, Dashboard users cannot be used for REST API authentication. Role-based API credentials are a feature of the EMQX Enterprise edition.

Create API Keys

You can manually create API keys for authentication on the Dashboard by navigating to System -> API Key. For instructions, see System - API Keys.

You can also create API keys using the bootstrap file method. Add the following configuration to the emqx.conf file to specify the file location:

api_key = {
  bootstrap_file = "etc/default_api_key.conf"
}

In the specified file, add multiple API keys in the format {API Key}:{Secret Key}:{?Role}, separated by new lines:

• API Key: Any string as the key identifier.
• Secret Key: Use a random string as the secret key.
• Role (optional): Specify the key's role, applicable only in the Enterprise edition.

For example:

my-app:AAA4A275-BEEC-4AF8-B70B-DAAC0341F8EB
ec3907f865805db0:Ee3taYltUKtoBVD9C3XjQl9C6NXheip8Z9B69BpUv5JxVHL:viewer
foo:3CA92E5F-30AB-41F5-B3E6-8D7E213BE97E:publisher

API keys created this way are valid indefinitely.

Each time EMQX starts, it will add the data set in the file to the API key list. If an API key already exists, its Secret Key and Role will be updated.

Roles and Permissions

In the EMQX Enterprise edition, the REST API implements role-based access control. When creating an API key, you can assign one of the following 3 predefined roles:

• Administrator: This role can access all resources and is the default value if no role is specified. The corresponding role identifier is administrator.
• Viewer: This role can only view resources and data, corresponding to all GET requests in the REST API. The corresponding role identifier is viewer.
• Publisher: Designed specifically for MQTT message publishing, this role is limited to accessing APIs related to message publishing. The corresponding role identifier is publisher.

Authentication Method

You can use the generated API Key and Secret Key as the username and password for Basic authentication:

• cURL
• Java
• Python
• Go
• JavaScript

curl -X GET http://localhost:18083/api/v5/nodes \
     -u 4f33d24d7b8e448d:gwtbmFJZrnzUu8mPK1BxUkBA66PygETiDEegkf1q8dD \
     -H "Content-Type: application/json"

import okhttp3.*;

import java.io.IOException;

public class EMQXNodesAPIExample {
    public static void main(String[] args) {
        try {
            String username = "4f33d24d7b8e448d";
            String password = "gwtbmFJZrnzUu8mPK1BxUkBA66PygETiDEegkf1q8dD";

            OkHttpClient client = new OkHttpClient();

            Request request = new Request.Builder()
                    .url("http://localhost:18083/api/v5/nodes")
                    .header("Content-Type", "application/json")
                    .header("Authorization", Credentials.basic(username, password))
                    .build();

            Response response = client.newCall(request).execute();
            System.out.println(response.body().string());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import urllib.request
import json
import base64

username = '4f33d24d7b8e448d'
password = 'gwtbmFJZrnzUu8mPK1BxUkBA66PygETiDEegkf1q8dD'

url = 'http://localhost:18083/api/v5/nodes'

req = urllib.request.Request(url)
req.add_header('Content-Type', 'application/json')

auth_header = "Basic " + base64.b64encode((username + ":" + password).encode()).decode()
req.add_header('Authorization', auth_header)

with urllib.request.urlopen(req) as response:
    data = json.loads(response.read().decode())

print(data)

package main

import (
    "fmt"
    "net/http"
    "bytes"
    "encoding/json"
)

func main() {
    username := "4f33d24d7b8e448d"
    password := "gwtbmFJZrnzUu8mPK1BxUkBA66PygETiDEegkf1q8dD"

    url := "http://localhost:18083/api/v5/nodes"

    req, err := http.NewRequest("GET", url, nil)
    if err != nil {
        panic(err)
    }
    req.SetBasicAuth(username, password)
    req.Header.Set("Content-Type", "application/json")

    client := &http.Client{}
    resp, err := client.Do(req)
    if err != nil {
        panic(err)
    }
    defer resp.Body.Close()

    buf := new(bytes.Buffer)
    _, err = buf.ReadFrom(resp.Body)
    if err != nil {
        panic(err)
    }

    var data interface{}
    json.Unmarshal(buf.Bytes(), &data)
    fmt.Println(data)
}

const axios = require('axios')

const username = '4f33d24d7b8e448d'
const password = 'gwtbmFJZrnzUu8mPK1BxUkBA66PygETiDEegkf1q8dD'

axios
  .get('http://localhost:18083/api/v5/nodes', {
    auth: {
      username: username,
      password: password,
    },
    headers: {
      'Content-Type': 'application/json',
    },
  })
  .then((response) => {
    console.log(response.data)
  })
  .catch((error) => {
    console.log(error)
  })

HTTP Headers

Unless otherwise specified, most API requests require the Accept header to be set to application/json, and then the response will be returned in JSON format.

HTTP Response Status Code

EMQX follows the HTTP Response Status Code standard, and the possible status codes are as follows:

Codes	Description
200	Request successfully, and the returned JSON data will provide more details
201	Created successfully, and the new object will be returned in the Body
204	Request successfully. Usually used for delete and update operations, and the returned Body will be empty
400	Bad Request. Usually request body or parameter error
401	Unauthorized. API key expires or does not exist.
403	Forbidden. Check if the object is in use or has dependency constraints.
404	Not Found. You can refer to the message field in the Body to check the reason
409	Conflict. The object already exists or the number limit is exceeded
500	Internal Server Error. Check the reason in the Body and logs

Pagination

For some APIs with large amounts of data, pagination functionality is provided. There are 2 types of pagination methods based on the data characteristics.

Page Number Pagination

In most APIs that support pagination, you can control the pagination by using the page (page number) and limit (page size) parameters. The maximum page size is 10000. If the limit parameter is not specified, the default is 100.

For example:

GET /clients?page=1&limit=100

In the response result, the meta field will contain pagination information. EMQX cannot predict the total number of data entries for requests using search conditions. Therefore, the meta.hasnext field indicates whether there is another page of data:

{
  "data":[],
  "meta":{
    "count":0,
    "limit":20,
    "page":1,
    "hasnext":false
  }
}

Cursor Pagination

In a few APIs where data changes rapidly, and page number pagination is inefficient, cursor pagination is used.

You can specify the starting position of the data using the position or cursor (starting position) parameter, and the limit (page size) parameter specifies the number of entries loaded from the starting position. The maximum page size is 10000. If the limit parameter is not specified, it defaults to 100.

For example:

GET /clients/{clientid}/mqueue_messages?position=1716187698257189921_0&limit=100

The meta field in the response will contain pagination information, with meta.position or meta.cursor indicating the starting position of the next page:

{
    "meta": {
        "start": "1716187698009179275_0",
        "position": "1716187698491337643_0"
    },
    "data": [
        {
            "inserted_at": "1716187698260190832",
            "publish_at": 1716187698260,
            "from_clientid": "mqttx_70e2eecf_10",
            "from_username": "undefined",
            "msgid": "000618DD161F682DF4450000F4160011",
            "mqueue_priority": 0,
            "qos": 0,
            "topic": "t/1",
            "payload": "SGVsbG8gRnJvbSBNUVRUWCBDTEk="
        }
    ]
}

This pagination method efficiently handles scenarios where data changes rapidly, ensuring continuity and efficiency in data retrieval.

Error Codes

Besides the HTTP response status codes, EMQX also defines a list of error codes to identify specific errors.

When an error happens, the error code is returned in JSON format by the Body:

# GET /clients/foo

{
  "code": "RESOURCE_NOT_FOUND",
  "reason": "Client id not found"
}

Error Codes	Description
WRONG_USERNAME_OR_PWD	Wrong username or password
WRONG_USERNAME_OR_PWD_OR_API_KEY_OR_API_SECRET	Wrong username & password or key & secret
BAD_REQUEST	Request parameters not legal
NOT_MATCH	Conditions not matched
ALREADY_EXISTS	Resources already exist
BAD_CONFIG_SCHEMA	Configuration data not legal
BAD_LISTENER_ID	Bad listener ID
BAD_NODE_NAME	Bad Node Name
BAD_RPC	RPC Failed. Check the cluster status and the requested node status
BAD_TOPIC	Topic syntax error, topic needs to comply with the MQTT protocol standard
EXCEED_LIMIT	Resources to be created exceed the maximum limit or minimum limit
INVALID_PARAMETER	Request parameters not legal and exceed the boundary value
CONFLICT	Conflicting request resources
NO_DEFAULT_VALUE	Request parameters do not use default values
DEPENDENCY_EXISTS	Resource depends on other resources
MESSAGE_ID_SCHEMA_ERROR	Message ID parsing error
INVALID_ID	Bad ID schema
MESSAGE_ID_NOT_FOUND	Message ID does not exist
NOT_FOUND	Resource not found or does not exist
CLIENTID_NOT_FOUND	Client ID not found or does not exist
CLIENT_NOT_FOUND	Client not found or does not exist(usually not an MQTT client)
RESOURCE_NOT_FOUND	Resource not found
TOPIC_NOT_FOUND	Topic not found
USER_NOT_FOUND	User not found
INTERNAL_ERROR	Server inter error
SERVICE_UNAVAILABLE	Service unavailable
SOURCE_ERROR	Source error
UPDATE_FAILED	Update fails
REST_FAILED	Reset source or configuration fails
CLIENT_NOT_RESPONSE	Client not responding