Switch to using config file

.gitignore

@@ -0,0 +1 @@
+/config

Dockerfile

@@ -18,7 +18,7 @@ RUN ln -st /usr/local/bin/ /coturn_exporter_files/coturn_exporter
 
 USER nobody:nogroup
 
-ENTRYPOINT []
-CMD ["coturn_exporter"]
+ENTRYPOINT ["coturn_exporter"]
+CMD []
 
 EXPOSE 9524/tcp

README.md

@@ -1,24 +1,92 @@
 # Coturn Exporter
 
-Tests whether a given TURN server is working and exports the result as a Prometheus metric
+Tests whether TURN servers are working and exports the result as a Prometheus metric
 
 ## How to Run It
 
 ```bash
 docker build -t coturn_exporter .
-docker run -e IP=1.2.3.4 -e PORT=1234 -e SECRET=qwerty -e INTERVAL=600 -e LOGLEVEL=INFO -p 127.0.0.1:80:9524 coturn_exporter
+echo 'ip: 1.2.3.4' > config  # Replace with your TURN server's IP; see below for port, secret, and more
+docker run \
+  --mount type=bind,src="$(pwd)"/config,dst=/coturn_exporter_files/config,readonly \
+  -p 127.0.0.1:80:9524 coturn_exporter
 ```
 
-All environment variables except `IP` are optional. `INTERVAL` (how many seconds to wait between checks) defaults to 900. `IP`, `PORT`, and `SECRET` refer to the TURN server to be checked. `LOGLEVEL` can be one of `DEBUG`, `INFO`, `WARNING`, `ERROR`, or `CRITICAL` and defaults to `WARNING`.
+## The Configuration File
+
+You must mount a configuration file into the container at `/coturn_exporter_files/config` to specify the TURN server(s) to be checked and optionally other settings. Its format is YAML.
+
+### `ip`, `port`, and `secret`
+
+If you have only one TURN server to check, you can specify its IP and optionally its port and/or secret at the root level of the config file.
+
+```yaml
+ip: 1.2.3.4
+port: 1234
+secret: qwerty
+```
+
+If no port is specified, 3478 is assumed.
+
+### `turn_servers`
+
+It is possible to specify more than one TURN server with the `turn_servers` key.
+
+```yaml
+turn_servers:
+  - ip: 1.2.3.4
+    port: 1234
+    secret: qwerty
+  - ip: 9.8.7.6
+    port: 9876
+    secret: asdf
+```
+
+You must use exactly one of `turn_servers` and `ip` \[+ `port`] \[+ `secret`] at the root level.
+
+### `interval`
+
+The optional key `interval` specifies the wait time between checks of each TURN server in seconds. It defaults to 900.
+
+```yaml
+interval: 333.33
+```
+
+### `loglevel`
+
+The optional key `loglevel` specifies the verbosity of the Coturn Exporter. It can be one of `DEBUG`, `INFO`, `WARNING`, `ERROR`, or `CRITICAL` and defaults to `WARNING`.
+
+```yaml
+loglevel: INFO
+```
+
+### A Complete Example
+
+```yaml
+---
+loglevel: INFO
+interval: 333.33
+turn_servers:
+  - ip: 1.2.3.4
+    port: 1234
+    secret: qwerty
+  - ip: 9.8.7.6
+    port: 9876
+    secret: asdf
+...
+```
 
 ## Output
 
-Metrics are exported on port 9524. They will include something like the following (plus some metrics added by the [Prometheus Python client](https://github.com/prometheus/client_python)):
+Metrics are exported on port 9524. They will look like the following (plus some metrics added by the [Prometheus Python client](https://github.com/prometheus/client_python)):
 
 ```
-# HELP turn_server_state the state of the TURN server
-# TYPE turn_server_state gauge
-turn_server_state{turn_server_state="ok"} 1.0
-turn_server_state{turn_server_state="not_ok"} 0.0
-turn_server_state{turn_server_state="unknown"} 0.0
+# HELP turnserver_state the state of the TURN server
+# TYPE turnserver_state gauge
+turnserver_state{host="1.2.3.4:1234",turnserver_state="ok"} 1.0
+turnserver_state{host="1.2.3.4:1234",turnserver_state="not_ok"} 0.0
+turnserver_state{host="1.2.3.4:1234",turnserver_state="unknown"} 0.0
+turnserver_state{host="9.8.7.6:9876",turnserver_state="ok"} 0.0
+turnserver_state{host="9.8.7.6:9876",turnserver_state="not_ok"} 1.0
+turnserver_state{host="9.8.7.6:9876",turnserver_state="unknown"} 0.0
 ```