private Map<String, String> metricsDimensionsForService(RoutingTable.Target target) {
        String applicationId = target.tenant().value() + "." + target.application().value();
        String app = target.application().value();
        if (target.instance().isPresent()) {
            app += "." + target.instance().get().value();
            applicationId += "." + target.instance().get().value();
        }
        return ImmutableMap.of(
                "tenantName", target.tenant().value(),
                "app", app,
                "applicationId", applicationId,
                "clusterid", target.cluster().value()
        );
    }
Report Nginx metrics periodically.

@author Morten Tokle
@author Martin Polden
routing-generator/src/main/java/com/yahoo/vespa/hosted/routing/nginx/NginxMetricsReporter.java