This folder contains the sinks for the cc-metric-collector.

# `metricSink.go`
The base class/configuration is located in `metricSink.go`.

# Sinks
* `stdoutSink.go`: Writes all metrics to `stdout` in InfluxDB line protocol. The sink does not use https://github.com/influxdata/line-protocol to reduce the executed code for debugging
* `influxSink.go`: Writes all metrics to an InfluxDB database instance using a blocking writer. It uses https://github.com/influxdata/influxdb-client-go . Configuration for the server, port, user, password and database name are in the global configuration file
* `natsSink.go`: Sends all metrics to an NATS server using the InfluxDB line protocol as encoding. It uses https://github.com/nats-io/nats.go . Configuration for the server, port, user, password and database name are in the global configuration file. The database name is used as subject for the NATS messages.

# Installation
Nothing to do, all sinks are pure Go code

# Contributing own sinks
A sink contains three functions and is derived from the type `Sink` (in `metricSink.go`):
* `Init(config SinkConfig) error`
* `Write(measurement string, tags map[string]string, fields map[string]interface{}, t time.Time) error`
* `Close()`

The data structures should be set up in `Init()` like opening a file or server connection. The `Write()` function takes a measurement, tags, fields and a timestamp and writes/sends the data. The `Close()` function should tear down anything created in `Init()`.

Finally, the sink needs to be registered in the `metric-collector.go`. There is a list of sinks called `Sinks` which is a map (string -> pointer to sink). Add a new entry with a descriptive name and the new sink.