The mosquitto-go-auth supports a couple of backends and it seems that all backends will be built anyway. For me so far only the MariaDB/MySQL backend is in use and thus tested and documented here.

Running the container

You can not run a container based on this image "out-of-the-box". You need to edit the configuration, and if desired, run all the Let's Encrypt stuff. For details see below.

The container exposed the ports 1883 (MQTT), 8883 (MQTT over SSL) and 9001 (MQTT over websockets). Only the configuration directory containing mosquitto.conf and friends is prepared as a volume.

Besides the mosquitto configuration volume, there are volume required for the Let's Encrypt configuration and state, the data directory of the broker and for the logfiles for supervisord.

Due to the requirements of certbot it also exposed the port 80 and 443. So, be careful when trying to start this image as a container on the same host as a webserver.

All logging is send into a dedicated logfile under control of supervisord.

To start the container a script is provided, which might need to adjusted to the actual environment:

#!/bin/bash

IMAGE=wollud1969/mosquitto-with-auth:latest
VOLUME_CONFIG=mosquitto-config
VOLUME_DATA=mosquitto-data
VOLUME_LOG=mosquitto-log
VOLUME_LETSENCRYPT=mosquitto-letsencrypt

docker volume inspect $VOLUME_CONFIG > /dev/null || docker volume create $VOLUME_CONFIG
docker volume inspect $VOLUME_DATA > /dev/null || docker volume create $VOLUME_DATA
docker volume inspect $VOLUME_LOG > /dev/null || docker volume create $VOLUME_LOG
docker volume inspect $VOLUME_LETSENCRYPT > /dev/null || docker volume create $VOLUME_LETSENCRYPT

docker pull $IMAGE

docker run \
  -d \
  --rm \
  -p80:80 \
  -p443:443 \
  -p1883:1883 \
  -p8883:8883 \
  -p9001:9001 \
  -v $VOLUME_CONFIG:/opt/etc/mosquitto \
  -v $VOLUME_DATA:/opt/data \
  -v $VOLUME_LOG:/var/log/supervisor \
  -v $VOLUME_LETSENCRYPT:/etc/letsencrypt \
  --name mosquitto \
  $IMAGE

The container expects the main configuration file in the root of the configuration volume named mosquitto.conf.

A very simple configuration, supporting MQTT on port 1883 and over TLS on port 8883 is:

log_dest stdout

persistence true
persistence_location /opt/data/

listener 1883
protocol mqtt
#allow_anonymous true
allow_anonymous false

listener 8883
protocol mqtt
#allow_anonymous true
allow_anonymous false
certfile /opt/etc/mosquitto/server.crt
keyfile /opt/etc/mosquitto/server.key
dhparamfile /opt/etc/mosquitto/dh.pem
tls_version tlsv1.2

auth_plugin /opt/lib/go-auth.so
auth_opt_log_dest stdout
auth_opt_log_level debug
auth_opt_backends mysql
auth_opt_mysql_host mariadb
auth_opt_mysql_port 3306
auth_opt_mysql_dbname mosquittoauth
auth_opt_mysql_user mosquittoauth
auth_opt_mysql_password xxx
auth_opt_mysql_allow_native_passwords true
auth_opt_mysql_userquery SELECT pw FROM users WHERE username = ?
auth_opt_mysql_aclquery SELECT topic FROM acls WHERE username = ? AND (rw & ?) != 0

The original readme of the mosquitto-go-auth plugin proposes a different acl query. However, that one didn't work for me. Maybe the meaning of the access attribute handed over from mosquitto core to the plugin has been changed in between. Actually, it appears to me that the meaning of this attribute has to be interpreted bitwise: Bit0 (1) is read access, Bit1 (2) is write access (publish), Bit0 and Bit1 (3) is readwrite access and Bit2 (4) is subscribe access. Write access is obviously and verified be test publish and subscribe access is also obviously subscribe. Currently I don't know what is meant be read access. For this reason I'm using a bitwise operation in the acl query. I set the rw column for those users who should have read-only access to 5 (1&4), for users who should only publish to 2 and for those ones who should read and write to 7 (1&2&4).

The required schema in the database is

CREATE TABLE users_t (
    id INTEGER AUTO_INCREMENT,
    username VARCHAR(25) NOT NULL,
    pw VARCHAR(512) NOT NULL,
    super INT(1) NOT NULL DEFAULT 0,
    PRIMARY KEY (id)
);
CREATE UNIQUE INDEX users_username ON users_t (username);

CREATE OR REPLACE VIEW users AS
  SELECT username, pw, super
    FROM users_t;

CREATE TABLE acls_t (
    id INTEGER AUTO_INCREMENT,
    user INTEGER NOT NULL,
    topic VARCHAR(256) NOT NULL,
    rw INTEGER(1) NOT NULL DEFAULT 1,	-- 1 is read, 2 is write, 3 is readwrite, 4 is subscribe
    PRIMARY KEY (id),
    CONSTRAINT `fk_book_author`
      FOREIGN KEY (user) REFERENCES users_t (id)
      ON DELETE CASCADE
      ON UPDATE CASCADE
    );
CREATE UNIQUE INDEX acls_user_topic ON acls_t (user, topic);

CREATE OR REPLACE VIEW acls AS
  SELECT a.topic, a.rw,
	 u.username
    FROM users_t u, acls_t a
    WHERE a.user = u.id;

The password is generated using the pw tool provided by mosquitto-go-auth, which is included in the image at /opt/bin. It can be used either within the container using docker exec -it <mosquitto-container> /opt/bin/pw. You may also try to copy it from the container onto your Linux host. It should run, since it is only linked against typical Linux libraries, however, I wouldn't do that.

For further information consult the readme and the examples in the mosquitto-go-auth project (https://github.com/iegomez/mosquitto-go-auth or https://github.com/wollud1969/mosquitto-go-auth).

Preparing configuration and certificates

Start the container using the provided start script, follow the container log using docker logs -f <containername>, you will see that supervisord start cron and mosquitto and you will see that the start of mosquitto fails
Go into the container using docker exec -it <containername> bash
Go into the directory /opt/etc/mosquitto, copy mosquitto.conf-sample into mosquitto.conf and edit it if required

If you want to register at Let's Encrypt and obtain a certificate follow the next steps:

Generate Diffie-Hellman parameters in the broker's configuration directory using openssl dhparam -out /opt/etc/mosquitto/dh.pem 2048
Register at Let's Encrypt using certbot register
Obtain a certificate using certbot certonly -d <domainname> --standalone, make sure to add the domainname into DNS first
Copy the deployment script into the deploy hooks directory of Let's Encrypt: cp /opt/bin/cert-deploy.sh /etc/letsencrypt/renewal-hooks/deploy/, edit it to fill in the right domainname
Run the deployment script manually for the very first deployment of certificates: env RENEWED_DOMAINS=<domainname> RENEWED_LINEAGE=/etc/letsencrypt/live/<domainname> ./cert-deploy.sh
The certificate and private key is now copied from the Let's Encrypt state directory into the configuration directory of mosquitto and the broker is restarted, you can observe that in the container logging output
Finally, test the broker using something like mosquitto_sub -h <domainname> -p 8883 --tls-version tlsv1.2 -v -t test and mosquitto_pub -h <domainname> -p 8883 --tls-version tlsv1.2 -t test -m test123
Renewal of the certificate will be triggered once a week