Air CO2 Exporter

Prometheus exporter for TFA Dostmann air CO2 monitor.

Air CO2 Exporter could read CO2 concentration and indoor temperature metrics from an AirCO2NTROL device.

This project is a golang implementation ported from the old Node.js project which shares similar functions. The new exporter reduced deployment file size and runtime dependencies, added support for the docker and kubernetes environment, and more easy to use.

Node.js exporter: https://github.com/huhamhire/co2-monitor-exporter

Contents

• Installation
  • Requirements
  • Dependencies
  • Install
• Usage
  • CLI
  • Systemd
  • Docker
  • Kubernetes
• Metrics
• Compatible Devices
• Troubleshooting
• License

Installation

Requirements

• Operating System: Linux
• CPU Architecture Supported:
  • amd64
  • arm64

Executable files can be built for other operating systems like Windows, OS X, or other platforms like ARM devices. However, there could be issues related to libusb library on OS other than Linux.

Dependencies

air_co2_exporter used libusb to read data from AirCO2NTROL devices.

# Debian / Ubuntu
sudo apt-get install -y libusb-1.0

# RHEL / CentOS
sudo yum install -y libusb-1.0

# Arch
sudo pacman -S libusb

# Alpine Linux
apk add libusb

Install

Download the air_co2_exporter executable file and put it under system path like /usr/local/bin/.

Usage

CLI

air_co2_exporter can be used as a normal program in foreground by shell.

$ air_co2_exporter --help
usage: air_co2_exporter [<flags>]

Flags:
  -h, --help                 Show context-sensitive help (also try --help-long and --help-man).
      --web.listen-address=":9110"
                             Address on which to expose metrics and web interface.
      --web.telemetry-path="/metrics"
                             Path under which to expose metrics.
  -t, --label.tag="default"  Tag for exposed metrics.
      --log.level=info       Only log messages with the given severity or above. One of: [debug, info, warn, error]
      --log.format=logfmt    Output format of log messages. One of: [logfmt, json]
      --version              Show application version.

Systemd

If you preferred to manage air_co2_exporter by systemd, a systemd unit file should be created.

• /etc/systemd/system/air_co2_exporter.service

  [Unit]
  Description=Air Co2 Exporter
  
  [Service]
  User=prometheus
  Group=prometheus
  Restart=on-failure
  ExecStart=/usr/local/bin/air_co2_exporter \
          --web.listen-address=:9110 \
          --log.level=warn
  
  [Install]
  WantedBy=default.target
  

Once unit file is created, you can manage air_co2_exporter like other systemd services.

systemctl daemon-reload

systemctl start air_co2_exporter
systemctl enable air_co2_exporter

Docker

air_co2_exporter is supported to be run in a docker container environment with privileged mode.

https://hub.docker.com/r/huhamhire/air-co2-exporter

A custom metrics tag can be set by environment variable LABEL_TAG.

docker run --privileged -p 9110:9110 huhamhire/air-co2-exporter:latest

Kubernetes

In addition to run with docker, air-co2-exporter image is supported to be managed in a kubernetes cluster.

Node(s) attached with AirCO2NTROL device can be managed by a specific label. And exporter pod could be deployed to these nodes later.

kubectl label node ${node_name} alpha.monitor.device/air-co2=exists

However, without a kubernetes device plugin implementation, only one air-co2-exporter pod can be managed on a single node. Use this exporter as DaemonSet is recommended in most scenarios.

⚠ IMPORTANT: Pod securityContext must be set to privileged mode for the exporter to access usb devices on kubernetes host node. Otherwise, it will encounter program panic cause by libusb error -99.

Here is an example kubernetes DaemonSet configuration.

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: air-co2-exporter
  namespace: temperature
  labels:
    app: air-co2-exporter
    prometheus: exporter
    sensor: air-co2
spec:
  selector:
    matchLabels:
      app: air-co2-exporter
  updateStrategy:
    type: RollingUpdate
  revisionHistoryLimit: 1
  template:
    metadata:
      labels:
        app: air-co2-exporter
      annotations:
        prometheus.io/port: '9110'
        prometheus.io/scrape: 'true'
    spec:
      restartPolicy: Always
      terminationGracePeriodSeconds: 0
      nodeSelector:
        alpha.monitor.device/air-co2: exists
      containers:
        - name: exporter
          image: huhamhire/air-co2-exporter:latest
          imagePullPolicy: IfNotPresent
          ports:
            - name: metrics
              hostPort: 9110
              containerPort: 9110
              protocol: TCP
          env:
            - name: LABEL_TAG
              value: my_custom_tag
          resources:
            limits:
              cpu: 100m
              memory: 100Mi
          securityContext:
            privileged: true
            capabilities:
              add:
                - SYS_ADMIN
              drop:
                - ALL
            readOnlyRootFilesystem: true
            allowPrivilegeEscalation: true

Metrics

• air_temp - Ambient Temperature (Tamb) in ℃.
• air_co2 - Relative Concentration of CO2 (CntR) in ppm.

Compatible Devices

• TFA Dostmann AirCO2NTROL Mini - Monitor CO2 31.5006.02
• CO2Meter RAD-0301 Mini CO2 Monitor

Other AirCO2NTROL devices with more metrics have not been tested. Supplement for compatible device list is always welcomed.

Limitations

• Only support Linux amd64 and arm64 platforms currently.
• air_co2_exporter could read metrics from only one AirCO2NTROL device only.
• Device ID (VID: 0x04D9, PID: 0xA052) of AirCO2NTROL Mini is hard coded in the exporter currently.

Troubleshooting

• libusb error -99

  panic: libusb: unknown error [code -99]
  

  This could happen when air_co2_exporter does not have sufficient privileges to access usb devices. Mostly caused by using a docker container environment without privileged mode.

• libusb not found

  air_co2_exporter: error while loading shared libraries: libusb-1.0.so.0: cannot open shared object file: No such file or directory
  

  libusb is required by gousb which used by air-co2-exporter to communicate with the device. libusb-1.0 library is required to be installed first.

• air_co2_exporter is not found by shell.

  sh: air_co2_exporter: not found
  

  Typically seen when used in Apline Linux docker images. Since Alpine image is a compact docker image with the size of only around 5 MB. It does not come with a GNU C library (glibc) by default which golang programs required. A glibc library like libc6-compat on Alpine is required.

License

MIT

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