A simple notifier that can publish build notifications to a topic on a MQTT broker.

MQTT is a machine-to-machine (M2M)/"Internet of Things" connectivity protocol. It was designed as an extremely lightweight publish/subscribe messaging transport.

The following details are configurable per Jenkins job:

• Broker URL - The URL to the MQTT broker (e.g. tcp://localhost:1883 or ssl://broker.example.com:8883).
• Credentials - Optional username/password credentials configured in Jenkins.
• Topic - Topic to publish notifications to (default: jenkins/$PROJECT_URL).
• Message - Message payload (default: $BUILD_RESULT).
• Notify on build start? - Optional toggle to send an MQTT notification when the build begins execution.
• Start Topic - Optional topic specifically for build start notifications (falls back to Topic).
• Start Message - Optional payload for build start notifications (default: STARTED).
• Notify on build completion? - Toggle to send notification upon build completion (default: true).
• Quality of Service - QoS level (0 - At most once, 1 - At least once, 2 - Exactly once).
• Retain Message? - Whether to set the retain flag on published messages.

Both topic and message strings support dynamic variable replacement:

• PROJECT_URL - The relative URL to the Jenkins project (e.g. "job/my-build/").
• BUILD_RESULT - The result of the build (e.g. SUCCESS, FAILURE, ABORTED, etc.).
• BUILD_NUMBER - The build number.
• BUILD_DISPLAY_NAME - The display name of the build (e.g. #1 or custom name).
• CULPRITS - Comma-separated list of build culprits.
• All standard Jenkins environment variables and build parameters.

The plugin provides the mqttNotification step for use in Jenkins Pipelines.

pipeline {
    agent any
    stages {
        stage('Build') {
            steps {
                echo 'Building...'
            }
        }
    }
    post {
        always {
            mqttNotification(
                brokerUrl: 'tcp://localhost:1883',
                topic: 'jenkins/builds/${JOB_NAME}',
                message: '{ "job": "${JOB_NAME}", "build": "${BUILD_NUMBER}", "status": "${BUILD_RESULT}" }',
                qos: '0',
                retainMessage: false,
                credentialsId: 'my-mqtt-credentials' // optional
            )
        }
    }
}

stage('Notify Start') {
    steps {
        mqttNotification(
            brokerUrl: 'tcp://localhost:1883',
            topic: 'jenkins/builds/${JOB_NAME}',
            message: 'Build ${BUILD_DISPLAY_NAME} started'
        )
    }
}

node {
    stage('Build') {
        mqttNotification brokerUrl: 'tcp://localhost:1883', topic: 'jenkins/start', message: 'Build started'
        // ... build steps ...
        mqttNotification brokerUrl: 'tcp://localhost:1883', topic: 'jenkins/finish', message: 'Build finished: ${BUILD_RESULT}'
    }
}

This Jenkins plugin is licensed under the MIT License.