homebridge-prometheus-exporter/README.md

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# Homebridge Prometheus Exporter
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> What if we could store homebridge metrics in Prometheus

*homebridge-prometheus-exporter* is a plugin for *homebridge* that provides a metrics endpoint for *Prometheus* to scrape.
Once the metrics are in *Prometheus*, they can be consumed and presented in various ways. One can use *Prometheus
Alerting Rules* to trigger actions on certain thresholds or *Grafana* to build informative graphs or alerts.

![A Grafana timeseries showing wattage and voltage of two home appliances on a timeseries chart](https://user-images.githubusercontent.com/79707/200554468-940da6fb-b1c8-4b2e-bd76-f5e208bf72a3.png)


## Installing

### Install the plugin

Run this command to install the plugin as a global *nodejs* module:

```shell
npm install -g homebridge-prometheus-exporter
```

### Configure *homebridge*

Edit the *homebridge* `config.json` to load the plugin:
```json lines
{
    // …
    "platforms": [
    {
      "platform": "PrometheusExporter",
      "pin": "123-12-123",
    },
    // …
  ]
}
```

### Customize *homebridge* startup

For *homebridge-prometheus-exporter* to work, *homebridge* has to run in "insecure mode". This means that any user who
has access to your network can control your *homebridge* devices. This is usually not a big problem but it is still
something you should consciously decide. *homebridge-config-ui-x*
[requires running in insecure mode](https://github.com/oznu/homebridge-config-ui-x/wiki/Enabling-Accessory-Control)
if you want to control your devices from *homebridge-config-ui-x*.

To enable "insecure mode", edit the startup script for *homebridge* and add `--insecure` or `-I`. Assuming you run
systemd, the proper way to override the config would be to use *systemd’s* drop-in mechanism.

Create `/etc/systemd/system/homebridge.service.d` folder:
```shell
mkdir /etc/systemd/system/homebridge.service.d
```
Write this drop-in configuration file to `/etc/systemd/system/homebridge.service.d/insecure.conf`:
```ini
[Service]
ExecStart=
ExecStart=/usr/lib/node_modules/homebridge/bin/homebridge --insecure
```

The first and empty `ExecStart` tells *systemd* to forget about the `ExecStart` from the original service definition
and the second `ExecStart` declares the new file. Run `systemctl daemon-reload` to refresh *systemd’s* unit database
and then run `systemd-delta --type=extended` to check if the drop-in worked as expected.

You should see something like this in the output:

```text
…
[EXTENDED]   /lib/systemd/system/homebridge.service → /etc/systemd/system/homebridge.service.d/insecure.conf
…
```

If you are not using *systemd*, first of all, you absolutely should but second of all you will likely have some sort
of env file, e.g. `/etc/defaults/homebridge` to customize the *homebridge* start command. Restart *homebridge* using
`systemctl restart homebridge`.

Test that the metrics endpoint is available by accesing `http://homebridge-host:36123/metrics`. You should see a
response similar to this:

```text
# TYPE homebridge_air_purifier_active gauge
homebridge_air_purifier_active{name="…",…} 0 1667914208196
# TYPE homebridge_air_purifier_current_air_purifier_state gauge
homebridge_air_purifier_current_air_purifier_state{name="…",…} 0 1667914208196
```

### Configuring *Prometheus*

With *homebridge-prometheus-exporter* up and running, it is now time to configure *Prometheus* to scrape the config
endpoint. Go to your prometheus host and edit `/etc/prometheus/prometheus.yml` and add the following scrape config:

```yml

scrape_configs:
  - job_name: homebridge-exporter
    static_configs:
    - targets:
      - homebridge-host:36123
```

Once *Prometheus* is restarted, metrics with the `homebridge_` prefix should start to be ingested.

### Customize *homebridge-prometheus-exporter*

*homebridge-prometheus-exporter* offers a few advanced settings to customize its behavior.

<!-- AUTOGENERATED CONFIG DOCS BEGIN -->
```json5
{
  // ...
  "platforms": [
    {
      "platform": "PrometheusExporter",


      // Pin
      //
      // Homebridge PIN for service authentication
      "pin": "<string>",


      // Debug
      "debug": "<boolean>",


      // Metrics prefix
      "prefix": "<string>",


      // Metrics server port
      //
      // TCP port where the Prometheus metrics server listens
      "port": "<integer>",


      // Metrics server interface
      //
      // Interface where the Prometheus metrics server listens. Can be an IP, a
      // hostname, "0.0.0.0" for all IPv4 interfaces, "::1" for all IPv6 interfaces.
      // Default is "::" which means "any interface"
      "interface": "<string>",


      // Service refresh interval
      //
      // Discover new services every <interval> seconds
      "refresh_interval": "<integer>",


      // Request timeout
      //
      // Request timeout when interacting with homebridge instances
      "request_timeout": "<integer>",


      // Service discovery timeout
      //
      // Discovery timeout after which the current discovery is considered failed
      "discovery_timeout": "<integer>",


      // TLS cert file
      //
      // Path to TLS certificate file (in PEM format)
      "tls_cert_file": "<string>",


      // TLS key file
      //
      // Path to TLS key file
      "tls_key_file": "<string>",


      // Basic auth username/password pairs
      //
      // Usernames and passwords for basic auth. Object key is the username, object
      // value is the password. Password must be encoded with bcrypt. Example:
      // {"joanna": "$2a$12$5/mmmRB28wg9yzaXhee5Iupq3UrFr/qMgAe9LvAxGoY5jLcfVGTUq"}
      "basic_auth": "<object>"
    }
  ]
}
```
<!-- AUTOGENERATED CONFIG DOCS END -->