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109 lines
3.6 KiB
Markdown
109 lines
3.6 KiB
Markdown
# CCMetric sinks
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This folder contains the SinkManager and sink implementations for the cc-metric-collector.
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# Available sinks:
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- [`stdout`](./stdoutSink.md): Print all metrics to `stdout`, `stderr` or a file
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- [`http`](./httpSink.md): Send metrics to an HTTP server as POST requests
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- [`influxdb`](./influxSink.md): Send metrics to an [InfluxDB](https://www.influxdata.com/products/influxdb/) database
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- [`influxasync`](./influxAsyncSink.md): Send metrics to an [InfluxDB](https://www.influxdata.com/products/influxdb/) database with non-blocking write API
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- [`nats`](./natsSink.md): Publish metrics to the [NATS](https://nats.io/) network overlay system
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- [`ganglia`](./gangliaSink.md): Publish metrics in the [Ganglia Monitoring System](http://ganglia.info/) using the `gmetric` CLI tool
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- [`libganglia`](./libgangliaSink.md): Publish metrics in the [Ganglia Monitoring System](http://ganglia.info/) directly using `libganglia.so`
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- [`prometeus`](./prometheusSink.md): Publish metrics for the [Prometheus Monitoring System](https://prometheus.io/)
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# Configuration
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The configuration file for the sinks is a list of configurations. The `type` field in each specifies which sink to initialize.
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```json
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{
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"mystdout" : {
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"type" : "stdout",
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"meta_as_tags" : [
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"unit"
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]
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},
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"metricstore" : {
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"type" : "http",
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"host" : "localhost",
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"port" : "4123",
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"database" : "ccmetric",
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"password" : "<jwt token>"
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}
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}
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```
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# Contributing own sinks
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A sink contains five functions and is derived from the type `sink`:
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* `Init(name string, config json.RawMessage) error`
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* `Write(point CCMetric) error`
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* `Flush() error`
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* `Close()`
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* `New<Typename>(name string, config json.RawMessage) (Sink, error)` (calls the `Init()` function)
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The data structures should be set up in `Init()` like opening a file or server connection. The `Write()` function writes/sends the data. For non-blocking sinks, the `Flush()` method tells the sink to drain its internal buffers. The `Close()` function should tear down anything created in `Init()`.
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Finally, the sink needs to be registered in the `sinkManager.go`. There is a list of sinks called `AvailableSinks` which is a map (`sink_type_string` -> `pointer to sink interface`). Add a new entry with a descriptive name and the new sink.
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## Sample sink
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```go
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package sinks
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import (
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"encoding/json"
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"log"
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lp "github.com/ClusterCockpit/cc-metric-collector/internal/ccMetric"
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)
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type SampleSinkConfig struct {
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defaultSinkConfig // defines JSON tags for 'name' and 'meta_as_tags'
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}
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type SampleSink struct {
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sink // declarate 'name' and 'meta_as_tags'
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config StdoutSinkConfig // entry point to the SampleSinkConfig
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}
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// Initialize the sink by giving it a name and reading in the config JSON
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func (s *SampleSink) Init(name string, config json.RawMessage) error {
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s.name = fmt.Sprintf("SampleSink(%s)", name) // Always specify a name here
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// Read in the config JSON
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if len(config) > 0 {
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err := json.Unmarshal(config, &s.config)
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if err != nil {
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return err
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}
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}
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return nil
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}
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// Code to submit a single CCMetric to the sink
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func (s *SampleSink) Write(point lp.CCMetric) error {
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log.Print(point)
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return nil
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}
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// If the sink uses batched sends internally, you can tell to flush its buffers
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func (s *SampleSink) Flush() error {
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return nil
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}
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// Close sink: close network connection, close files, close libraries, ...
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func (s *SampleSink) Close() {}
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// New function to create a new instance of the sink
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func NewSampleSink(name string, config json.RawMessage) (Sink, error) {
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s := new(SampleSink)
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err := s.Init(name, config)
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return s, err
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}
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```
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