Fix statsd metrics collection for metric names with ":"

[odin-delrio]

Statsd server is ignoring malformed metrics. This change introduces a basic sanitizing to metric names for avoid losing those metrics.

Why is this needed at this level?

Because current statsd clients for JAVA are not dealing with this... I proposed the change to that clients but I did not get an answer (here and here)

Is Spring Boot producing metric names with ":"?

Yes, if you are using hystrix you will get metrics like this one:

 "gauge.servo.hystrix.hystrixcommand.https://mydomain.com.myfeignservice#getsomething(string).rollingcountshortcircuited": 0.0,

This kind of metrics are simply ignored by statsd servers.

Do you need a workaround?

For those that need this fixed right now, you can override the bean definition:

  @Bean
  @ExportMetricWriter
  @ConditionalOnMissingBean
  @ConditionalOnProperty(prefix = "spring.metrics.export.statsd", name = "host")
  public StatsdMetricWriter statsdMetricWriter(MetricExportProperties properties) {
    MetricExportProperties.Statsd statsdProperties = properties.getStatsd();
    return new StatsdMetricWriter(statsdProperties.getPrefix(), statsdProperties.getHost(), statsdProperties.getPort()) {
      @Override
      public void increment(Delta<?> delta) {
        super.increment(new Delta<Number>(sanitizeMetricName(delta.getName()), delta.getValue(), delta.getTimestamp()));
      }

      @Override
      public void set(Metric<?> metric) {
        super.set(new Metric<Number>(sanitizeMetricName(metric.getName()), metric.getValue(), metric.getTimestamp()));
      }

      private String sanitizeMetricName(String name) {
        return name.replace(":", "");
      }
    };
  }

[philwebb]

/cc @dsyer @spencergibb

[philwebb]

Looking at https://github.com/b/statsd_spec is seems that : is reserved as a separator. It would be nice if your other PR was merged and the Java client took care of this, but I can't see any harm in us doing it as well.

[dsyer]

LGTM. I might have suggested an alternative separator ("-" instead of ":" maybe?).