influxer

influxer is a simple tool to observe messages published to an mqtt broker and store them in influxdb.

This is a tool I built for myself and my own readings because existing tools were too complicated and I wanted something I could understand.

QuickStart

Here's a really simple example to get you started:

from mqtt://your.mqtt.broker/#clientid {
    watch "home/kitchen/temperature" float [site="myhouse", room="kitchen"] field="temperature" measurement="env"
}

In the example, you can see the kitchen thermometer is being read and stored in an influxdb measurement called env with numeric value of the reading being stored as the field temperature with the tags myhouse and kitchen. Allowing you to issue queries like:

select last(temperature) from env where room='kitchen'

...if you have a lot of thermometers deployed like that, you can use topic wildcards and positional variables for mapping back to tags. e.g., the following is similar, but supports all rooms:

from mqtt://your.mqtt.broker/#clientid {
    watch "home/+/thermometer" float [site="myhouse", room=$2] field="temperature" measurement="env"
}

For a more advanced example, if you have temperature and humidity sensors in the same form, you can do the following:

from mqtt://your.mqtt.broker/#clientid {
    watch "home/+/+" float [site="myhouse", room=$2] field=$3 measurement="env"
}

In practice, I end up with a lot of patterns I'm observing, so I tend to use match instead of watch. match is like watch, but doesn't subscribe. So I'll often do something that looks more like this:

from mqtt://your.mqtt.broker/#clientid {
    // Only put temperature and humidity readings into the env measurement
    match "home/+/temperature" float [site="myhouse", room=$2] field=$3 measurement="env"
    match "home/+/humidity" float [site="myhouse", room=$2] field=$3 measurement="env"

    match "home/+/battery" int [site="myhouse", thing=$2] measurement="battery"

    // This causes us to subscribe to everything under home, but
    // anything not explicitly matched is ignored.
    watch "home/#" ignore
}

We also support JSON via jsonpointer for parsing fields out of JSON payloads. For example, if you use tasmota with something like POWR2 sensor/switches, you get a lot of interesting telemetry reported like this:

{
  "Time": "2021-07-03T10:41:53",
  "ENERGY": {
    "TotalStartTime": "2019-01-16T05:53:10",
    "Total": 459.394,
    "Yesterday": 0.667,
    "Today": 0.223,
    "Period": 0,
    "Power": 0,
    "ApparentPower": 0,
    "ReactivePower": 0,
    "Factor": 0,
    "Voltage": 119,
    "Current": 0
  }
}

This is useful data, so let's build on our previous example to import it:

from mqtt://your.mqtt.broker/#clientid {
    // Only put temperature and humidity readings into the env measurement
    match "home/+/temperature" float [site="myhouse", room=$2] field=$3 measurement="env"
    match "home/+/humidity" float [site="myhouse", room=$2] field=$3 measurement="env"

    match "home/+/battery" int [site="myhouse", thing=$2] measurement="battery"

    match "home/+/tele/SENSOR" jsonp {
          measurement "pow" [which=$1]
          "total"      <- "/ENERGY/Total"
          "yesterday"  <- "/ENERGY/Yesterday"
          "today"      <- "/ENERGY/Today"
          "power"      <- "/ENERGY/Power"
          "voltage"    <- "/ENERGY/Voltage"
          "current"    <- "/ENERGY/Current"
    }


    // This causes us to subscribe to everything under home, but
    // anything not explicitly matched is ignored.
    watch "home/#" ignore
}

Config Syntax

The config is a series of blocks that are specific to an mqtt connection. If you want to observe multiple mqtt brokers, or just have different client auth requirements, go for it.

Each block starts with the literal string "from" followed by an MQTT URL and then the collection of watches for that source.

Matches and watches are the same syntax and concept. The only difference between match and watch is whether an explicit subscription is requested for the item. As shown in quickstart, a blanket watch near the bottom can simplify subscriptions a bit.

Each item consists of an optional QoS, a filter, and an extractor. The default QoS is 2, but qos0 qos1 or qos2 may be specified between the literal watch and the filter if your needs are different.

After the topic, you specify your extractor. There are three matcher types:

Ignore

Ignore is what it sounds like, and lets you ignore topics that your watch may have picked up, but don't provide any useful value. In the quick start examples, it's the catch-all for the broad watch, allowing influxer to see all of the messages, but ignore the ones it doesn't have specific plans for.

Simple Value

The simple value parser is meant for processing topics that send single values per topic. (e.g., your thermometer just sends 25 for the temperature). A handful of parsers are available for mapping to useful influxdb fields:

• int
• float
• bool
• string
• auto

Most of these are fairly obvious. auto means approximately the same thing as float currently as that's what sensor values often end up looking like. If you're unsure, you can be explicit.

Tags are optional, but are generally quite useful string values attached to rows in influxdb to allow you to discriminate values in queries. You specify them by adding [tag1="val", tag2="val"] after the value parser. Tag values can reference topic segments using $X for topic field position X (one-based). e.g., if the topic is home/bedroom/thermometer, then $1 is home and $2 is bedroom, etc...

Next, you specify the influxdb field that will receive the value. The default is value, otherwise you can specify field="temperature" or use a topic field position.

Finally, you can specify the measurement. The default is the full name of the topic, which is probably not great, but it makes it easy to grab all the things with minimal effort.

Here are are a few complete example:

watch "a/b/c" auto
watch qos0 "some/thing" int measurement="things"
watch "+/temp" field=$1 measurement="temps"
watch "+/+/+" [sensor=$2] field=$3 measurement=$1

JSON

The JSON extractor allows field extractions using jsonpointer to nest multiple influxdb values into a single mqtt message handler.

It's somewhat related to the Simple Value parser, but the measurement and tags are shared for the entire block, and JSON values are pulled into explicitly named fields. The format is jsonp { ... } where ... contains

measurement "mname" [tag1="tagv"]
"field1" <- "/json/path" auto
"field2" <- "/json/path2"
"field3" <- "/json/path3" int

Both "mname" and "tagv" can use $ topic vars and tags may be omitted if you don't want any.

After your measurement declaration, we have one or more specific field extractors in the form of:

"fieldname" <- "/json/path" auto

auto may be omitted or replaced with any other simple value parser.