simple-prom/README.md

# simple-prom

A simple and easy to use module for Prometheus metric exporting.

## Usage

Create an instance of SimpleProm using `SimpleProm.init`
```ts
import SimpleProm from "simple-prom";

const instance = SimpleProm.init({});
```
See [IConfig](https://git.eusv.net/Catgirl.Enterprises/simple-prom/src/branch/master/interfaces/IConfig.ts) for config values to use in `SimpleProm.init`

### Self hosted usage
SimpleProm can self host it's own http server for metrics polling, simple pass "selfHost: true" in the init config.
```ts
const instance = SimpleProm.init({
	selfHost: true,
	selfHostPort: 1337 // Optional, defaults to 9100
});
```

### Use your own http server
Simply passing an empty config `{}` will get you what you want here, to get the metrics data call `getMetricText()` on your SimpleProm instance.
You can then use it as you normally would with anything, in this example with express:
```ts
const instance = SimpleProm.init({});

req.get("/metrics", (req, res) => res.end(instance.getMetricText()));
```

## Creating metrics
To add a metric call the `addMetric` method on your SimpleProm instance, passing in a metric object.

Currently supported metric types are:
- [Counter](https://prometheus.io/docs/concepts/metric_types/#counter)
- [Gauge](https://prometheus.io/docs/concepts/metric_types/#gauge)

Support for all metric types is planned.

Example for Counter:
```ts
const instance = SimpleProm.init({});

const httpRequests = instance.addMetric(new Counter("app_http_requests_handled"));
httpRequests.setHelpText("The number of HTTP requests handled since startup");
httpRequests.add(1);
```

Example for Gauge:
```ts
const instance = SimpleProm.init({});

const onlineUsers = instance.addMetric(new Gauge("app_online_users"));
onlineUsers.setHelpText("The number of online users");
onlineUsers.Value = 1234;
```