MQTT

Detailed documentation on the MQTT pubsub component

Setup MQTT


You can run a MQTT broker locally using Docker:

docker run -d -p 1883:1883 -p 9001:9001 --name mqtt eclipse-mosquitto:1.6.9

You can then interact with the server using the client port: mqtt://localhost:1883


You can run a MQTT broker in kubernetes using following yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mqtt-broker
  labels:
    app-name: mqtt-broker
spec:
  replicas: 1
  selector:
    matchLabels:
      app-name: mqtt-broker
  template:
    metadata:
      labels:
        app-name: mqtt-broker
    spec:
      containers:
        - name: mqtt
          image: eclipse-mosquitto:1.6.9
          imagePullPolicy: IfNotPresent
          ports:
            - name: default
              containerPort: 1883
              protocol: TCP
            - name: websocket
              containerPort: 9001
              protocol: TCP
---
apiVersion: v1
kind: Service
metadata:
  name: mqtt-broker
  labels:
    app-name: mqtt-broker
spec:
  type: ClusterIP
  selector:
    app-name: mqtt-broker
  ports:
    - port: 1883
      targetPort: default
      name: default
      protocol: TCP
    - port: 9001
      targetPort: websocket
      name: websocket
      protocol: TCP

You can then interact with the server using the client port: tcp://mqtt-broker.default.svc.cluster.local:1883

Create a Dapr component

The next step is to create a Dapr component for MQTT.

Create the following yaml file named mqtt.yaml

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: <NAME>
  namespace: <NAMESPACE>
spec:
  type: pubsub.mqtt
  metadata:
  - name: url
    value: "tcp://[username][:password]@host.domain[:port]"
  - name: qos
    value: 1
  - name: retain
    value: "false"
  - name: cleanSession
    value: "false"

To configure communication using TLS, ensure mosquitto broker is configured to support certificates. Pre-requisite includes certficate authority certificate, ca issued client certificate, client private key. Make following additional changes to mqtt pubsub components for supporting TLS.

...
spec:
  type: pubsub.mqtt
  metadata:
  - name: url
    value: "tcps://host.domain[:port]"
  - name: caCert
    value: ''
  - name: clientCert
    value: ''
  - name: clientKey
    value: ''

Where:

  • url (required) is the address of the MQTT broker.
    • use tcp:// scheme for non-TLS communication.
    • use tcps:// scheme for TLS communication.
  • qos (optional) indicates the Quality of Service Level (QoS) of the message. (Default 0)
  • retain (optional) defines whether the message is saved by the broker as the last known good value for a specified topic. (Default false)
  • cleanSession (optional) will set the “clean session” in the connect message when client connects to an MQTT broker . (Default true)
  • caCert (required for using TLS) is the certificate authority certificate.
  • clientCert (required for using TLS) is the client certificate.
  • clientKey (required for using TLS) is the client key.

Apply the configuration

Visit this guide for instructions on configuring pub/sub components.