MQTT

Detailed documentation on the MQTT pubsub component

Setup MQTT

You can run a MQTT broker locally using Docker:

  1. 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:

  1. apiVersion: apps/v1
  2. kind: Deployment
  3. metadata:
  4.   name: mqtt-broker
  5.   labels:
  6.     app-name: mqtt-broker
  7. spec:
  8.   replicas: 1
  9.   selector:
  10.     matchLabels:
  11.       app-name: mqtt-broker
  12.   template:
  13.     metadata:
  14.       labels:
  15.         app-name: mqtt-broker
  16.     spec:
  17.       containers:
  18.         - name: mqtt
  19.           image: eclipse-mosquitto:1.6.9
  20.           imagePullPolicy: IfNotPresent
  21.           ports:
  22.             - name: default
  23.               containerPort: 1883
  24.               protocol: TCP
  25.             - name: websocket
  26.               containerPort: 9001
  27.               protocol: TCP
  28. ---
  29. apiVersion: v1
  30. kind: Service
  31. metadata:
  32.   name: mqtt-broker
  33.   labels:
  34.     app-name: mqtt-broker
  35. spec:
  36.   type: ClusterIP
  37.   selector:
  38.     app-name: mqtt-broker
  39.   ports:
  40.     - port: 1883
  41.       targetPort: default
  42.       name: default
  43.       protocol: TCP
  44.     - port: 9001
  45.       targetPort: websocket
  46.       name: websocket
  47.       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

  1. apiVersion: dapr.io/v1alpha1
  2. kind: Component
  3. metadata:
  4.   name: <NAME>
  5.   namespace: <NAMESPACE>
  6. spec:
  7.   type: pubsub.mqtt
  8.   version: v1
  9.   metadata:
  10.   - name: url
  11.     value: "tcp://[username][:password]@host.domain[:port]"
  12.   - name: qos
  13.     value: 1
  14.   - name: retain
  15.     value: "false"
  16.   - name: cleanSession
  17.     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.

  1. ...
  2. spec:
  3.   type: pubsub.mqtt
  4.   metadata:
  5.   - name: url
  6.     value: "tcps://host.domain[:port]"
  7.   - name: caCert
  8.     value: ''
  9.   - name: clientCert
  10.     value: ''
  11.   - name: clientKey
  12.     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.

Warning

The above example uses secrets as plain strings. It is recommended to use a secret store for the secrets as described here.

Apply the configuration

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

Related links

Last modified February 16, 2021: Merge pull request #1235 from dapr/update-v0.11 (b4e9fbb)