DHT22 prometheus exporter

This repository creates a Prometheus exporter container so that metrics can be collected by a Prometheus agent and displayed in any kind of dashboard such as Grafana.

Run the container

• Copy the .env.example file into a .env file and fill the values from your own
• Run this command to build and start the container:

> docker-compose up -d
...
Starting dht22_exporter_rpi ... done

• Verify that the sensor is correctly collecting data with:

> docker logs dht22_exporter_rpi
<2022-08-19 12:53:20,747> <INFO> <Set GPIO-Pin to D22 and SleepTime to 15sec>
<2022-08-19 12:53:20,754> <INFO> <Starting Prometheus client on port 9090>
<2022-08-19 12:53:21,106> <INFO> <Temp: 82.9 F / 28.3 C    Humidity: 58.1%>
<2022-08-19 12:53:21,107> <INFO> <Sleeping for 15 seconds>
<2022-08-19 12:53:36,465> <INFO> <Temp: 82.9 F / 28.3 C    Humidity: 59.4%>
<2022-08-19 12:53:36,465> <INFO> <Sleeping for 15 seconds>
<2022-08-19 12:53:51,832> <ERROR> <Checksum did not validate. Try again.>
<2022-08-19 12:54:07,195> <INFO> <Temp: 82.9 F / 28.3 C    Humidity: 58.4%>
<2022-08-19 12:54:07,195> <INFO> <Sleeping for 15 seconds>
<2022-08-19 12:54:22,563> <ERROR> <Checksum did not validate. Try again.>
<2022-08-19 12:54:37,930> <ERROR> <Checksum did not validate. Try again.>
<2022-08-19 12:54:53,298> <INFO> <Temp: 82.9 F / 28.3 C    Humidity: 58.2%>

• Verify that the /metrics is showing the metrics details with:

> curl localhost:9090/metrics
# HELP python_gc_objects_collected_total Objects collected during gc
# TYPE python_gc_objects_collected_total counter
python_gc_objects_collected_total{generation="0"} 100.0
python_gc_objects_collected_total{generation="1"} 273.0
python_gc_objects_collected_total{generation="2"} 0.0
# HELP python_gc_objects_uncollectable_total Uncollectable object found during GC
# TYPE python_gc_objects_uncollectable_total counter
python_gc_objects_uncollectable_total{generation="0"} 0.0
python_gc_objects_uncollectable_total{generation="1"} 0.0
python_gc_objects_uncollectable_total{generation="2"} 0.0
# HELP python_gc_collections_total Number of times this generation was collected
# TYPE python_gc_collections_total counter
python_gc_collections_total{generation="0"} 42.0
python_gc_collections_total{generation="1"} 3.0
python_gc_collections_total{generation="2"} 0.0
# HELP python_info Python platform information
# TYPE python_info gauge
python_info{implementation="CPython",major="3",minor="9",patchlevel="5",version="3.9.5"} 1.0
# HELP process_virtual_memory_bytes Virtual memory size in bytes.
# TYPE process_virtual_memory_bytes gauge
process_virtual_memory_bytes 1.8038784e+07
# HELP process_resident_memory_bytes Resident memory size in bytes.
# TYPE process_resident_memory_bytes gauge
process_resident_memory_bytes 1.1784192e+07
# HELP process_start_time_seconds Start time of the process since unix epoch in seconds.
# TYPE process_start_time_seconds gauge
process_start_time_seconds 1.66091359955e+09
# HELP process_cpu_seconds_total Total user and system CPU time spent in seconds.
# TYPE process_cpu_seconds_total counter
process_cpu_seconds_total 0.97
# HELP process_open_fds Number of open file descriptors.
# TYPE process_open_fds gauge
process_open_fds 7.0
# HELP process_max_fds Maximum number of open file descriptors.
# TYPE process_max_fds gauge
process_max_fds 1.048576e+06
# HELP dht22_temperature_celsius Temperature in celsius provided by dht sensor
# TYPE dht22_temperature_celsius gauge
dht22_temperature_celsius{location_name="Paris",location_country="FR",location="livingroom"} 28.3
# HELP dht22_temperature_fahrenheit Temperature in fahrenheit provided by dht sensor
# TYPE dht22_temperature_fahrenheit gauge
dht22_temperature_fahrenheit{location_name="Paris",location_country="FR",location="livingroom"} 82.9
# HELP dht22_humidity Humidity in percents provided by dht sensor
# TYPE dht22_humidity gauge
dht22_humidity{location_name="Paris",location_country="FR",location="livingroom"} 59.4
# HELP dht22_read_failures_total Count of the DHT22 sensor read failures
# TYPE dht22_read_failures_total counter
dht22_read_failures_total{location_name="Paris",location_country="FR",location="livingroom"} 20.0
# HELP dht22_read_failures_created Count of the DHT22 sensor read failures
# TYPE dht22_read_failures_created gauge
dht22_read_failures_created{location_name="Paris",location_country="FR",location="livingroom"} 1.660913631833311e+09

Known issues

The collection of the data from the sensor is not 100% available all the time. Sometimes the sensor fails to collect it and the error Checksum did not validate. Try again. is thrown into the logs.

When this happens, this increments the counter dht22_read_failures

Test

Tested on Raspberry 4 model B on Raspbian GNU/Linux 10 (buster)

Reference

The code in this repository has been inspired by:

• https://github.com/Tob1as/rpi-sensors
• https://github.com/clintjedwards/dht22_exporter