Table of Contents

• What is HiveMQ?
• HiveMQ Docker Images
  • HiveMQ Base Image
  • HiveMQ DNS Discovery Image
  • Tags
• Basic Single Instance
• Clustering
  • Local Cluster with Docker Swarm
    • Managing the Cluster
  • Production Use with Kubernetes
    • Accessing the HiveMQ Control Center
    • Accessing the MQTT Port Using External Clients
• Configuration
  • Setting the HiveMQ Control Center Username and Password
  • Adding a License
  • Disabling the hivemq-allow-all-extension
  • Disabling Privilege Step-Down
  • Overriding the Cluster Bind Address
  • Setting the Cluster Transport Type

What is HiveMQ?

HiveMQ is a MQTT based messaging platform designed for the fast, efficient and reliable movement of data to and from connected IoT devices. It uses the MQTT protocol for instant, bi-directional push of data between your device and your enterprise systems. HiveMQ is built to address some of the key technical challenges organizations face when building new IoT applications, including:

• Building reliable and scalable business critical IoT applications
• Fast data delivery to meet the expectations of end users for responsive IoT products
• Lower cost of operation through efficient use of hardware, network and cloud resources
• Integrating IoT data into existing enterprise systems

While at its core, HiveMQ is an MQTT 3.1, MQTT 3.1.1 and MQTT 5.0 compliant MQTT broker, HiveMQ excels with its additional features designed for enterprise use cases and professional deployments.

See Features for more information.

HiveMQ Docker Images

This repository provides the Dockerfile and context for the images hosted in the HiveMQ Docker Hub repository.

HiveMQ Base Image

The HiveMQ base image installs and optimizes the HiveMQ installation for execution as a container.

It is meant to be used to build custom images or to run a dockerized HiveMQ locally for testing purposes.

How to Build

The image can then be built by running the command HIVEMQ_VERSION=4.7.3 ./build.sh in the hivemq4/base-image folder. An alternative image name can be specified with the environment variable TARGETIMAGE, example: TARGETIMAGE=myregistry/custom-hivemq:1.2.3 HIVEMQ_VERSION=4.7.3 ./build.sh

HiveMQ DNS Discovery Image

The HiveMQ DNS discovery image is based on the HiveMQ base image and adds the HiveMQ DNS Discovery Extension.

We recommend using the HiveMQ DNS discovery image to run HiveMQ in a cluster.

How to Build

To build the DNS discover image, you must first obtain the HiveMQ DNS Discovery Extension, unzip the file and copy the folder to the hivemq4/dns-image folder.

The image can then be built by running docker build -t hivemq-dns . in the hivemq4/dns-image folder.

Tags

The HiveMQ Docker Hub repository provides different versions of the HiveMQ images using tags:

Basic Single Instance

To start a single HiveMQ instance and allow access to the MQTT port as well as the Control Center, get Docker and run the following command:

docker run --ulimit nofile=500000:500000 -p 8080:8080 -p 8000:8000 -p 1883:1883 hivemq/hivemq4

You can connect to the broker via MQTT (1883) or Websockets (8000) or the Control Center (8080) via the respective ports.

Clustering

For running HiveMQ in a cluster, we recommend using the DNS discovery image. This image has the HiveMQ DNS Discovery Extension built in. It can be used with any container orchestration engine that supports service discovery using a round-robin A record.

A custom solution supplying the A record could be used as well.

Environment Variables

The following environment variables can be used to customize the discovery and broker configuration respectively.

Following are two examples, describing how to use this image on Docker Swarm and Kubernetes respectively.

Other environments are compatible as well (provided they support DNS discovery in some way).

Entrypoint Scripts

There is a /docker-entrypoint.d directory which you can COPY custom entrypoint scripts to which will be executed before running HiveMQ. The scripts must follow the XX_name.sh naming scheme, where XX is an integer number that will determine the ordering in which the entrypoint scripts are executed.

Depending on the executable bit within the image, they will be either executed normally, or if the executable bit is not set, they will be sourced and run in the parent shell. Sourcing allows you to set custom environment variables from an entrypoint script before startup.

Local Cluster with Docker Swarm

To start a HiveMQ cluster locally, you can use Docker Swarm.

Note: Using Docker Swarm in production is not recommended.

• Start a single node Swarm cluster by running:

docker swarm init

• Create an overlay network for the cluster nodes to communicate on:

docker network create -d overlay --attachable myNetwork

• Create the HiveMQ service on the network

docker service create \
  --replicas 3 --network myNetwork \
  --env HIVEMQ_DNS_DISCOVERY_ADDRESS=tasks.hivemq \
  --publish target=1883,published=1883 \
  --publish target=8080,published=8080 \
  -p 8000:8000/udp \
  --name hivemq \
    hivemq/hivemq4:dns-latest

This will provide a 3 node cluster with the MQTT (1883) and HiveMQ Control Center (8080) ports forwarded to the host network.

This means you can connect MQTT clients on port 1883. The connection will be forwarded to any of the cluster nodes.

The HiveMQ HiveMQ Control Center can be used in a single node cluster. A sticky session for the HTTP requests in clusters with multiple nodes cannot be upheld with this configuration, as the internal load balancer forwards requests in an alternating fashion. To use sticky sessions the Docker Swarm Enterprise version is required.

Managing the Cluster

To scale the cluster up to 5 nodes, run

docker service scale hivemq=5

To remove the cluster, run

docker service rm hivemq

To read the logs for all HiveMQ nodes in real time, use

docker service logs hivemq -f

To get the log for a single node, get the list of service containers using

docker service ps hivemq

And print the log using

docker service logs <id>

where <id> is the container ID listed in the service ps command.

Production Use with Kubernetes

NOTE: Please consider using the Kubernetes Operator instead, as it makes production deployment of HiveMQ much easier.

For production we recommend using the DNS discovery image in combination with Kubernetes.

On Kubernetes, an appropriate deployment configuration is necessary to utilize DNS discovery. A headless service will provide a DNS record for the broker that can be used for discovery.

Following is an example configuration for a HiveMQ cluster with 3 nodes using DNS discovery in a replication controller setup.

Please note that you may have to replace HIVEMQ_DNS_DISCOVERY_ADDRESS according to your Kubernetes namespace and configured domain.

apiVersion: v1
kind: ReplicationController
metadata:
  name: hivemq-replica
spec:
  replicas: 3
  selector:
    app: hivemq-cluster1
  template:
    metadata:
      name: hivemq-cluster1
      labels:
        app: hivemq-cluster1
    spec:
      containers:
      - name: hivemq-pods
        image: hivemq/hivemq4:dns-latest
        ports:
        - containerPort: 8080
          protocol: TCP
          name: hivemq-control-center
        - containerPort: 1883
          protocol: TCP
          name: mqtt
        env:
        - name: HIVEMQ_DNS_DISCOVERY_ADDRESS
          value: "hivemq-discovery.default.svc.cluster.local."
        - name: HIVEMQ_DNS_DISCOVERY_TIMEOUT
          value: "20"
        - name: HIVEMQ_DNS_DISCOVERY_INTERVAL
          value: "21"
        - name: HIVEMQ_CLUSTER_TRANSPORT_TYPE
          value: "TCP"
        readinessProbe:
          tcpSocket:
            port: 1883
          initialDelaySeconds: 30
          periodSeconds: 60
          failureThreshold: 60
        livenessProbe:
          tcpSocket:
            port: 1883
          initialDelaySeconds: 30
          periodSeconds: 60
          failureThreshold: 60
---
kind: Service
apiVersion: v1
metadata:
  name: hivemq-discovery
  annotations:
    service.alpha.kubernetes.io/tolerate-unready-endpoints: "true"
spec:
  selector:
    app: hivemq-cluster1
  ports:
    - protocol: TCP
      port: 1883
      targetPort: 1883
  clusterIP: None

Accessing the HiveMQ Control Center

To access the HiveMQ HiveMQ Control Center for a cluster running on Kubernetes, follow these steps:

• Create a service exposing the HiveMQ Control Center of the HiveMQ service. Use the following YAML definition (as web.yaml):

kind: Service
apiVersion: v1
metadata:
  name: hivemq-control-center
spec:
  selector:
    app: hivemq-cluster1
  ports:
    - protocol: TCP
      port: 8080
      targetPort: 8080
  sessionAffinity: ClientIP
  type: LoadBalancer

• Create the service using kubectl create -f web.yaml

Note: Depending on your provider of Kubernetes environment, load balancers might not be available or additional configuration may be necessary to access the HiveMQ Control Center.

Accessing the MQTT Port Using External Clients

To allow access for the MQTT port of a cluster running on Kubernetes, follow these steps:

• Create a service exposing the MQTT port using a load balancer. You can use the following YAML definition (as mqtt.yaml):

kind: Service
apiVersion: v1
metadata:
  name: hivemq-mqtt
  annotations:
    service.spec.externalTrafficPolicy: Local
spec:
  selector:
    app: hivemq-cluster1
  ports:
    - protocol: TCP
      port: 1883
      targetPort: 1883
  type: LoadBalancer

• Create the service using kubectl create -f mqtt.yaml

Note: The externalTrafficPolicy annotation is necessary to allow the Kubernetes service to maintain a larger amount of concurrent connections.
See Source IP for Services for more information.

Configuration

Setting the HiveMQ Control Center Username and Password

The environment variable HIVEMQ_CONTROL_CENTER_PASSWORD allows you to set the password of the HiveMQ Control Center by defining a SHA256 hash for a custom password.

Additionally, you can also configure the username, using the environment variable HIVEMQ_CONTROL_CENTER_USER.

See Generate a SHA256 Password to read more about how to generate the password hash.

Adding a License

To use a license with a HiveMQ docker container, you must first encode it as a string.

To do so, run cat license.lic | base64 (replace license.lic with the path to your license file).

Set the resulting string as the value for the HIVEMQ_LICENSE environment variable of the container.

Disabling the hivemq-allow-all-extension

By default the HiveMQ docker images use the packaged hivemq-allow-all-extension.

This can be circumvented by setting the HIVEMQ_ALLOW_ALL_CLIENTS environment variable to false.

This will cause the entrypoint script to delete the extension on startup.

Disabling Privilege Step-Down

By default the HiveMQ docker images check for root privileges at startup and, if present, switch to a less privileged user before running the HiveMQ broker.

This will enhance the security of the container.

If you wish to skip this step, set the environment variable HIVEMQ_NO_ROOT_STEP_DOWN to false.

Overriding the Cluster Bind Address

By default the HiveMQ DNS discovery image attempts to set the bind address using the containers ${HOSTNAME} to ensure that HiveMQ will bind the cluster connection to the correct interface so a cluster can be formed.

This behavior can be overridden by setting any value for the environment variable HIVEMQ_BIND_ADDRESS. The broker will attempt to use the given value as the bind address instead.

Setting the Cluster Transport Type

By default the HiveMQ DNS discovery image uses UDP as transport protocol for the cluster transport.

If you would like to use TCP as transport type instead, you can set the HIVEMQ_CLUSTER_TRANSPORT_TYPE environment variable to TCP.

Note: We generally recommend using TCP for the cluster transport, as it makes HiveMQ less susceptible to network splits under high network load.

Building a custom Docker image

See our documentation for more information on how to build custom HiveMQ images.

Contributing

If you want to contribute to HiveMQ 4 Docker Images, see the contribution guidelines.

License

HiveMQ 4 Docker Images is licensed under the APACHE LICENSE, VERSION 2.0. A copy of the license can be found here.