EMQX

Quick reference

• Where to get help:

https://emqx.io or https://github.com/emqx/emqx

• Where to file issues:

https://github.com/emqx/emqx/issues

• Supported architectures

  amd64, arm64v8

• Supported Docker versions:

  the latest release

What is EMQX

EMQX is the world's most scalable open-source MQTT broker with a high performance that connects 100M+ IoT devices in 1 cluster, while maintaining 1M message per second throughput and sub-millisecond latency.

EMQX supports multiple open standard protocols like MQTT, HTTP, QUIC, and WebSocket. It's 100% compliant with MQTT 5.0 and 3.x standard, and secures bi-directional communication with MQTT over TLS/SSL and various authentication mechanisms.

With the built-in powerful SQL-based rules engine, EMQX can extract, filter, enrich and transform IoT data in real-time. In addition, it ensures high availability and horizontal scalability with a masterless distributed architecture, and provides ops-friendly user experience and great observability.

EMQX boasts more than 20K+ enterprise users across 50+ countries and regions, connecting 100M+ IoT devices worldwide, and is trusted by over 400 customers in mission-critical scenarios of IoT, IIoT, connected vehicles, and more, including over 70 Fortune 500 companies like HPE, VMware, Verifone, SAIC Volkswagen, and Ericsson.

How to use this image

Run EMQX

Execute some command under this docker image

$ docker run -d --name emqx emqx/emqx:${tag}

For example

$ docker run -d --name emqx -p 18083:18083 -p 1883:1883 emqx/emqx:latest

The EMQX broker runs as Linux user emqx in the docker container.

Configuration

All EMQX Configuration in etc/emqx.conf can be configured via environment variables.

By default, the environment variables with EMQX_ prefix are mapped to key-value pairs in configuration files.

You can change the prefix by overriding HOCON_ENV_OVERRIDE_PREFIX.

Example:

EMQX_LISTENERS__SSL__DEFAULT__ACCEPTORS <--> listeners.ssl.default.acceptors
EMQX_ZONES__DEFAULT__MQTT__MAX_PACKET_SIZE <--> zones.default.mqtt.max_packet_size

• Prefix EMQX_ is removed
• All upper case letters is replaced with lower case letters
• __ is replaced with .

If HOCON_ENV_OVERRIDE_PREFIX=DEV_ is set:

DEV_LISTENER__SSL__EXTERNAL__ACCEPTORS <--> listener.ssl.external.acceptors
DEV_MQTT__MAX_PACKET_SIZE              <--> mqtt.max_packet_size
DEV_LISTENERS__TCP__DEFAULT__BIND      <--> listeners.tcp.default.bind

For example, set MQTT TCP port to 1883

$ docker run -d --name emqx -e DEV_LISTENERS__TCP__DEFAULT__BIND=1883 -p 18083:18083 -p 1883:1883 emqx/emqx:latest

Please read more about EMQX configuration in the official documentation.

EMQX node name configuration

Options	Default	Mapped	Description
EMQX_NAME	container name	none	EMQX node short name
EMQX_HOST	container IP	none	EMQX node host, IP or FQDN

These environment variables are used during container startup phase only in docker-entrypoint.sh.

If EMQX_NAME and EMQX_HOST are set, and EMQX_NODE_NAME is not set, EMQX_NODE_NAME=$EMQX_NAME@$EMQX_HOST. Otherwise EMQX_NODE_NAME is taken verbatim.

Cluster

EMQX supports a variety of clustering methods, see our documentation for details.

Let's create a static node list cluster from docker-compose.

• Create docker-compose.yaml:

  version: '3'
  
  services:
    emqx1:
      image: emqx/emqx:latest
      environment:
      - "EMQX_NAME=emqx"
      - "EMQX_HOST=node1.emqx.io"
      - "EMQX_CLUSTER__DISCOVERY_STRATEGY=static"
      - "EMQX_CLUSTER__STATIC__SEEDS=[emqx@node1.emqx.io, emqx@node2.emqx.io]"
      networks:
        emqx-bridge:
          aliases:
          - node1.emqx.io
  
    emqx2:
      image: emqx/emqx:latest
      environment:
      - "EMQX_NAME=emqx"
      - "EMQX_HOST=node2.emqx.io"
      - "EMQX_CLUSTER__DISCOVERY_STRATEGY=static"
      - "EMQX_CLUSTER__STATIC__SEEDS=[emqx@node1.emqx.io, emqx@node2.emqx.io]"
      networks:
        emqx-bridge:
          aliases:
          - node2.emqx.io
  
  networks:
    emqx-bridge:
      driver: bridge

• Start the docker-compose cluster

  docker-compose -p my_emqx up -d

• View cluster

  $ docker exec -it my_emqx_emqx1_1 sh -c "emqx_ctl cluster status"
  Cluster status: #{running_nodes => ['emqx@node1.emqx.io','emqx@node2.emqx.io'],
                    stopped_nodes => []}

Persistence

If you want to persist the EMQX docker container, you need to keep the following directories:

• /opt/emqx/data
• /opt/emqx/etc
• /opt/emqx/log

Since data in these folders are partially stored under the /opt/emqx/data/mnesia/${node_name}, the user also needs to reuse the same node name to see the previous state. In detail, one needs to specify the two environment variables: EMQX_NAME and EMQX_HOST, EMQX_HOST set as 127.0.0.1 or network alias would be useful.

In if you use docker-compose, the configuration would look something like this:

volumes:
  vol-emqx-data:
    name: foo-emqx-data
  vol-emqx-etc:
    name: foo-emqx-etc
  vol-emqx-log:
    name: foo-emqx-log

services:
  emqx:
    image: emqx/emqx:latest
    restart: always
    environment:
      EMQX_NAME: foo_emqx
      EMQX_HOST: 127.0.0.1
    volumes:
      - vol-emqx-data:/opt/emqx/data
      - vol-emqx-etc:/opt/emqx/etc
      - vol-emqx-log:/opt/emqx/log

Note that /opt/emqx/etc contains some essential configuration files. If you want to mount a host directory in the container to persist configuration overrides, you will need to bootstrap it with default configuration files.

Kernel Tuning

Under Linux host machine, the easiest way is Tuning guide.

If you want tune Linux kernel by docker, you must ensure your docker is latest version (>=1.12).

docker run -d --name emqx -p 18083:18083 -p 1883:1883 \
    --sysctl fs.file-max=2097152 \
    --sysctl fs.nr_open=2097152 \
    --sysctl net.core.somaxconn=32768 \
    --sysctl net.ipv4.tcp_max_syn_backlog=16384 \
    --sysctl net.core.netdev_max_backlog=16384 \
    --sysctl net.ipv4.ip_local_port_range=1000 65535 \
    --sysctl net.core.rmem_default=262144 \
    --sysctl net.core.wmem_default=262144 \
    --sysctl net.core.rmem_max=16777216 \
    --sysctl net.core.wmem_max=16777216 \
    --sysctl net.core.optmem_max=16777216 \
    --sysctl net.ipv4.tcp_rmem=1024 4096 16777216 \
    --sysctl net.ipv4.tcp_wmem=1024 4096 16777216 \
    --sysctl net.ipv4.tcp_max_tw_buckets=1048576 \
    --sysctl net.ipv4.tcp_fin_timeout=15 \
    emqx/emqx:latest

REMEMBER: DO NOT RUN EMQX DOCKER PRIVILEGED OR MOUNT SYSTEM PROC IN CONTAINER TO TUNE LINUX KERNEL, IT IS UNSAFE.

Thanks

• @je-al
• @RaymondMouthaan
• @zhongjiewu