mqttbroker - A broker for messages on MQTT

Installation

Installation using Docker

docker run -it --rm --name mqttbroker -v mqttbroker.conf:/etc/mqttbroker.conf docker.io/gbeine/mqttbroker

Installation using Podman

podman run -it --rm --name mqttbroker -v mqttbroker.conf:/etc/mqttbroker.conf docker.io/gbeine/mqttbroker

Native installation with Python venv

The installation requires at least Python 3.9.

Philosophy is to install it under /usr/local/lib/mqttbroker and control it via systemd.

cd /usr/local/lib
git clone https://github.com/gbeine/mqttbroker.git
cd mqttbroker
./install

The install script creates a virtual python environment using the venv module. All required libraries are installed automatically. Depending on your system this may take some time.

Configuration

The configuration is located in /etc/mqttbroker.conf.

Each configuration option is also available as command line argument.

• copy mqttbroker.conf.example
• configure as you like

option	default	arguments	comment
mqtt_host	'localhost'	-m, --mqtt_host	The hostname of the MQTT server.
mqtt_port	1883	--mqtt_port	The port of the MQTT server.
mqtt_keepalive	30	--mqtt_keepalive	The keep alive interval for the MQTT server connection in seconds.
mqtt_clientid	'airrohr2mqtt'	--mqtt_clientid	The clientid to send to the MQTT server.
mqtt_user	-	-u, --mqtt_user	The username for the MQTT server connection.
mqtt_password	-	-p, --mqtt_password	The password for the MQTT server connection.
mqtt_topic	'airrohr'	-t, --mqtt_topic	The topic to publish MQTT message.
mqtt_tls	-	--mqtt_tls	Use SSL/TLS encryption for MQTT connection.
mqtt_tls_version	'TLSv1.2'	--mqtt_tls_version	The TLS version to use for MQTT. One of TLSv1, TLSv1.1, TLSv1.2.
mqtt_verify_mode	'CERT_REQUIRED'	--mqtt_verify_mode	The SSL certificate verification mode. One of CERT_NONE, CERT_OPTIONAL, CERT_REQUIRED.
mqtt_ssl_ca_path	-	--mqtt_ssl_ca_path	The SSL certificate authority file to verify the MQTT server.
mqtt_tls_no_verify	-	--mqtt_tls_no_verify	Do not verify SSL/TLS constraints like hostname.
verbose	-	-v, --verbose	Be verbose while running.
-	'/etc/mqttbroker.conf'	-c, --config	The path to the config file.
topics	see below	-	The configuration for the topics handling.

Topics handling

Forwarding topics

The most easy case - just forward one topic on another

{
    "topic": "target/topic/1",
    "sources": [
      "source/topic/1"
    ]
}

There can be many sources, the last one wins

{
    "topic": "target/topic/1",
    "sources": [
      "source/topic/1",
      "source/topic/2"
    ]
}

Connect topics bidirectional

{
    "topic": "target/topic/1"
    "sources": [
      "source/topic/1"
    ],
},
{
    "topic": "source/topic/1"
    "sources": [
      "target/topic/1"
    ],
}

Dealing with data types

type can be one of str, int, float, bool ('true' or 'false' in lower cases), and bool_int ('1' or '0'). bool accepts 'true', '1', 'on', 'yes' as values for true.

For all data types it is possible to set an initial value using init. This is helpful if values should be combined and there is no SLA when partial values will be published on MQTT.

{
    "topic": "target/topic/str_example",
    "sources": [
      "source/topic/str_example"
    ],
    "type": "str"
},
{
    "topic": "target/topic/int_example",
    "sources": [
      "source/topic/int_example"
    ],
    "type": "int"
},
{
    "topic": "target/topic/float_example",
    "sources": [
      "source/topic/float_example"
    ],
    "type": "float"
},
{
    "topic": "target/topic/bool_example",
    "sources": [
      "source/topic/bool_example"
    ],
    "type": "bool"
},
{
    "topic": "target/topic/bool_int_example",
    "sources": [
      "source/topic/bool_int_example"
    ],
    "type": "bool_int"
},
{
    "topic": "target/topic/bool_example",
    "sources": [
      "source/topic/bool_example"
    ],
    "type": "bool",
    "init": "false"
},
{
    "topic": "target/topic/bool_int_example",
    "sources": [
      "source/topic/bool_int_example"
    ],
    "type": "bool_int",
    "init": 1
}

Math on MQTT

int and float can be modified by a factor (multiply) and rounded to a specific number of digits. The factor is always applied before rounding.

{
    "topic": "target/topic/rounded_by_2",
    "sources": [
      "source/topic/1"
    ],
    "type": "float",
    "round": 2
},
{
    "topic": "target/topic/multiplied_by_10",
    "sources": [
      "source/topic/1"
    ],
    "type": "int",
    "factor": 10
},
{
    "topic": "target/topic/multiplied_by_0_01_rounded_by_2",
    "sources": [
      "source/topic/1"
    ],
    "type": "float",
    "factor": 0.01,
    "round": 2
}

Numeric values can be added and the min and max values can be determined. Of course, factor and round can be applied to the results.

{
    "topic": "target/topic/1_plus_2",
    "sources": [
      "source/topic/1",
      "source/topic/2"
    ],
    "handle": "add",
    "type": "float"
},
{
    "topic": "target/topic/minimum",
    "sources": [
      "source/topic/1",
      "source/topic/2",
      "source/topic/3"
    ],
    "handle": "min",
    "type": "int",
    "factor": 10
},
{
    "topic": "target/topic/maximum",
    "sources": [
      "source/topic/1",
      "source/topic/2",
      "source/topic/3"
    ],
    "handle": "max",
    "type": "float",
    "round": 2
}

Combining topics

Multiple topics can be combined to a string. If a certain length is required, the missing values can be appended.

{
    "topic": "target/topic/combined",
    "sources": [
      "source/topic/1",
      "source/topic/2"
    ],
    "handle": "combine"
},
{
    "topic": "target/topic/combined_append",
    "sources": [
      "source/topic/1",
      "source/topic/2",
      "source/topic/3"
    ],
    "handle": "combine",
    "append": [0, "test", 0, 0, 0, 0, 10]
}

Splitting topics

And topics containing multiple values can be splitted, of course. The split is based on spaces in the payload string. The selection uses array counting, so the first value has index 0, the second value has index 1, and so on.

{
    "topic": "target/topic/selected_1",
    "sources": [
      "source/topic/1"
    ],
    "handle": "split",
    "select": 0,
    "type": int
},
{
    "topic": "target/topic/selected_2",
    "sources": [
      "source/topic/1"
    ],
    "handle": "split"
    "select": 2,
    "type": float,
    "factor": 0.1,
    "round": 1
}

Running mqttbroker

I use systemd to manage my local services.

Support

I have not the time (yet) to provide professional support for this project. But feel free to submit issues and PRs, I'll check for it and honor your contributions.

License

The whole project is licensed under BSD-3-Clause license. Stay fair.