qmp-testing-suite/golang-producer-consumer/vendor/gitlab-app.eng.qops.net/golang/metrics

author: alexanderh@qualtrics.com

Sending Metrics with golang/metrics

This guide will walk you through how to configure a Go client to send metrics to the metrics service.

If you are looking for how to record runtime metrics about your Go application check out the [_____ guide found _____](TODO insert link).

Click here for the full GoDoc for the golang/metrics package.

Configuring hiera

Each production host has a telegraf agent that accepts statsD UDP packets to be forwarded on to the metrics service. In the hiera confiuration for your app you need to add telegraf to the container's host file and inject the local telegraf address as an environment variable.

docker::apps:
  app:
      ...
      docker_args: >
        --add-host="telegraf:%{::ipaddress}"
        -e STATS_REPORTER_ADDRESS="telegraf:8125"        

Using golang/metrics

You can use the the package-level DefaultReporter or create an instance of a Reporter to be passed to you application's types.

Package-level Reporter

To use the DefaultReporter you need to enable it. In your main func, enable the reporter before your app starts. Note that you will use the environment variable that you configured in hiera.

func main() {
	if err := metrics.EnableStatsDReporter(
	    "my_cannonical_service_id",
	    metrics.AddressFromEnv("STATS_REPORTER_ADDRESS"),
	); err != nil {
		fmt.Printf("unable to connect to statsd: %v", err)
	}

	// Ensure that metrics are flushed on shutdown
	defer metrics.DefaultReporter.Close()
}

// Somewhere in the application
metrics.IncCounter("my_request", metrics.Tag("foo", "bar"))

!!! warning Metrics are buffered before being sent to StatsD. If your application does not close the DefaultReporter before shutdown, some collected metrics may be lost. (In the future, this package's API may be updated to better reflect this.)

Then within your application you can call the other package-level funcs to send metrics.

metrics.IncCounter("my_request", metrics.Tag("foo", "bar"))
// or
defer metrics.NewTimer("http_request", Tag("protocol", "http2")).Record()

!!! info Note that when metrics.EnableStatsDReporter is used to enable the DefaultReporter the golang/http/accesslog package will use that DefaultReporter to send timing metrics of each request handled. The sent http_request_time metric will be tagged with status_code and name (which is the id/name provided by the consumer with accesslog.SetRequired(ctx, accesslog.Name, ...))

Reporter Instance

To create an instance of a Reporter use the constructor.

reporter, err := metrics.NewReporter(
	"my_cannonical_service_id", 
	metrics.AddressFromEnv("STATS_REPORTER_ADDRESS"),
)
if err != nil {
	fmt.Printf("unable to connect to statsd: %v", err)
}

Then within your application pass the reporter variable to your types and call the methods rather than the package-level funcs.

reporter.IncCounter("my_request", metrics.Tag("foo", "bar"))
// or
defer reporter.NewTimer("http_request", Tag("protocol", "http2")).Record()

Now your metrics can be queried in grafana or kairos!