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A step-by-step guide for starting a mosquitto broker service in a container with docker-compose

#docker #mqtt #mosquitto #broker

A step-by-step guide for starting a mosquitto broker service in a container with docker-compose

Prerequisites

Before we start, make sure you have the following installed on your machine:

  • Docker
  • docker-compose

You can install the prerequisites following this tutorial.

  • Open your terminal and create a new directory called mosquitto: 
 mkdir mosquitto
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  • Change to the mosquitto directory: 
 cd mosquitto
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  • Create the config folder and the mosquitto.conf and password.txt files inside it (with the content as follows): 
 mkdir config echo 'listener 1883 persistence true persistence_location /mosquitto/data/ log_dest file /mosquitto/log/mosquitto.log allow_anonymous false password_file /mosquitto/config/password.txt' > config/mosquitto.conf echo "admin:\$7\$101\$xuOfObQdv0Hi2p0A\$o+J3vzbpm0hekukYw73tT3fiB2Ogi1UCJgbzNyFA0GOgxAo79hqfTeXVr062KoD5nCphwV+1V/NxlMzwnV5Kvg==" > config/password.txt
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  • Create the log folder and the mosquitto.log file inside it: 
 mkdir log touch log/mosquitto.log
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  • Set the read and write permissions for all users for the following files: 
 chmod o+w log/mosquitto.log chmod 766 -R config
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  • Create the docker-compose.yml file with the following content: 
 version: '3.8' networks: mqtt-net: driver: bridge ipam: driver: default config: - subnet: 172.100.10.0/24 services: mqtt-broker: image: eclipse-mosquitto:latest user: mosquitto volumes: - type: bind source: ./config/ target: /mosquitto/config/ read_only: false - type: bind source: ./log/ target: /mosquitto/log/ read_only: false - type: volume source: data target: /mosquitto/data/ ports: - target: 1883 published: 1883 protocol: tcp mode: host - target: 9001 published: 9001 protocol: tcp mode: host networks: mqtt-net: ipv4_address: 172.100.10.10 mqtt-pub: image: eclipse-mosquitto:latest command: sh -c "mosquitto_pub -h mqtt-broker -t test -m 'Hello World' -u admin -P password" depends_on: - mqtt-broker networks: mqtt-net: ipv4_address: 172.100.10.11 mqtt-sub: image: eclipse-mosquitto:latest command: sh -c "mosquitto_sub -h mqtt-broker -t test -u admin -P password" depends_on: - mqtt-broker networks: mqtt-net: ipv4_address: 172.100.10.12 volumes: data: name: "mqtt-broker-data"
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Note that we have assigned a static IP address of 172.100.10.10 to the mqtt-broker service.

  • Build and start the containers by running the following command: 
 docker-compose up --build
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This should bring up 3 services, namely mqtt-broker, mqtt-pub, and mqtt-sub. The mqtt-pub service will immediately exit since it exits after publishing a message.

The default username and password for mqtt-broker are admin and password, respectively.

  • We can now publish messages using the mqtt-pub service: 
 docker compose run mqtt-pub sh -c "mosquitto_pub -h mqtt-broker -t test -m 'Hello World' -u admin -P password" docker compose run mqtt-pub sh -c "mosquitto_pub -h mqtt-broker -t test -m 'Message 2' -u admin -P password" docker compose run mqtt-pub sh -c "mosquitto_pub -h mqtt-broker -t test -m 'Message 3' -u admin -P password"
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The output should be as follows:

 mqtt-mqtt-sub-1 | Hello World mqtt-mqtt-sub-1 | Message 2 mqtt-mqtt-sub-1 | Message 3
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  • To change the password of the admin user (after changing the password, the service needs to be restarted): 
 docker compose exec mqtt-broker mosquitto_passwd -b /mosquitto/config/password.txt admin NEWPASSWORD
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Restart the container:

 docker compose restart mqtt-broker
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  • Since we changed the admin password, we will no longer be able to start the mqtt-pub service with docker compose up mqtt-sub. We need to start it using the following command:

    docker compose run mqtt-sub sh -c "mosquitto_sub -h mqtt-broker -t test -u admin -P CHANGED_PASSWORD"

    Now we can publish a message (using another terminal) and see it reflected in the mqtt-sub container service:

    docker compose run mqtt-pub sh -c "mosquitto_pub -h mqtt-broker -t test -m 'Hello World' -u admin -P CHANGED_PASSWORD"

How do manage the user info in a separate databse?

Top comments (1)

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ceentaxerror profile image
Syntax • • Edited

Your indentation is all screwed up. Any chance you can fix it for future travellers?

Docker compose build errors out because you are defining the driver twice, once as bridge then again as default.

Should be:

networks: mqtt-net: driver: bridge ipam: config: - subnet: 172.100.10.0/24
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You also get the message "volumes must be a mapping", this is because there is an indentation error on the data: field.

Should be:

volumes: data: name: "mqtt-broker-data"
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But after all of that still getting an invalid IPv4 address for the subscriber.

Any ideas?