MQTT

In our previous post EMQX 5.x HTTP password authentication server minimal example using NodeJS we provided a complete example of how to implement EMQX HTTP authentication.

This post provides an extension to our previous HTTP auth by adding a Koa router (i.e. a HTTP endpoint / URL) to provide ACL authentication, i.e. allow or deny topic level access with custom logic.

router.post('/emqx/acl', async ctx => {
    const body = ctx.request.body;
    console.log(body)
    // TODO: This example always returns true
    // You need to implement your authentication logic
    ctx.body = {
        result: "allow",
    };
});

Add that code before app.use(router.routes()); in the script from EMQX 5.x HTTP password authentication server minimal example using NodeJS.

My recommended Authorization configuration body which you can set in the EMQX dashboard is

{
  "action": "${action}",
  "client_id": "${clientid}",
  "ip": "${peerhost}",
  "topic": "${topic}",
  "username": "${username}"
}

Note: If you also want to implement ACL authorization via HTTP, see our extension to this example: EMQX 5.x HTTP ACL server using NodeJS

This server implements a minimal HTTP authentication server. In this minimal example, it will always allow authentication – you need to implement your own logic to verify passwords. Note: This server is written for EMQX versionx5.0 and will not work for EMQX 4.x without modification. See the official documentation on EMQX 5.x HTTP auth for more information.

#!/usr/bin/env node
const router = require('koa-router')();
const koaBody = require('koa-body');
const Koa = require('koa');
const app = new Koa();

app.use(koaBody());

router.post('/emqx/auth', async ctx => {
    const body = ctx.request.body;
    const username = body.username;
    const password = body.password;
    // TODO: This example always returns "allow"
    // You need to implement your authentication logic
    ctx.body = {
        result: "allow",
        is_superuser: false
    };
});

app.use(router.routes());

if (!module.parent) app.listen(19261);

This script is based on our previous post Minimal Koa.JS example with Router & Body parser, hence you can install the dependencies using

npm i --save koa koa-router koa-body

The request body config which you can set in the EMQX dashboard is

{
  "client_id": "${clientid}",
  "password": "${password}",
  "username": "${username}"
}