Mosquitto Showcase

Java application sending messages to Eclipse Mosquitto broker, that is monitored by Node-RED.

My little exploration of how to do stuff.

MQTT Version 3.1.1

Mosquitto

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Docker

• It is the same for both 3.1.1 and 5.0

1. Prepare local folders and the config file mosquitto.conf

> mkdir c:\DockerShared\Mosquitto\
> mkdir c:\DockerShared\Mosquitto\Data
> vim c:\DockerShared\Mosquitto\mosquitto.conf

# Optional: Listener for WebSockets (port 9001)
listener 9001
protocol websockets

# Allow anonymous connections (set to false if you want authentication)
allow_anonymous true

# Optional: Password file for users (when allow_anonymous is false)
#password_file /mosquitto/config/passwords.txt

# Persistence (saves the messages when the broker restarts)
persistence true
persistence_location /mosquitto/data/

# Log to stdout (good for seeing logs in Docker container logs)
log_dest stdout

# Optional: Define logging level
log_type error
log_type warning
log_type notice
log_type information

# Optional: Set max client connections (default is no limit)
# max_connections 100

# Optional: Set client keep-alive time (default is 60 seconds)
# keepalive_interval 60

• The password file is generated with mosquitto_passwd utility

2. Pull & Run the Broker

> docker run --name mosquitto -it -p 1883:1883 -p 9001:9001 ^
    -v c:\DockerShared\Mosquitto\mosquitto.conf:/mosquitto/config/mosquitto.conf ^
    -v c:\DockerShared\Mosquitto\Data:/mosquitto/data ^
    eclipse-mosquitto:2.0.19

3. Test the instance

Open two consoles with

docker exec -it mosquitto /bin/sh

In the first, listen.

mosquitto_sub -h localhost -p 1883 -t "test/topic"

And in the other, send a message

mosquitto_pub -h localhost -p 1883 -t "test/topic" -m "test message"

Node-RED

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Docker

1. Pull & Run the Server

> docker run --name node-red -it -p 1880:1880 ^
    -v c:\DockerShared\Node-RED\Data:/data ^
    nodered/node-red:4.0.3-22

2. Configure the Debugger

1. Open the Web Console
2. Add mqtt in node (from network section).
3. Add new server,
   • the address is from docker DNS: 'mosquitto',
   • select "subscribe to single topic" and
   • fill in the topic name test/topic.
4. Done.
5. Add debug node (common section).
6. Connect the nodes.
7. Deploy.

Test

Now send some messages again (also this application sends the messages, and you should see them in the debug panel (2nd icon from the right, on the right side of the screen).

Run the Docker Image

Run with docker plugin (pom-configured hostname is mosquitto as in docker DNS)

> mvn clean package
> mvn docker:run -Dbroker.hostname=<optional mqtt broker hostname> 

or old school (default hostname is localhost)

> mvn clean package
> cd target
> java -jar demo-mosquitto-1.0.0.jar <optional mqtt broker hostname>

Run with Docker Compose

Build everything, including the docker image, with maven:

> mvn clean package
> docker compose up -d

Open the Node-RED Web Console and watch the incoming messages.

Now play with anything you want.