Metrics Additional Attributes

SkyWalking provides OAL and MAL to analyze the data source and generate the metrics. Generally, the metrics fields in the storage include name, entity_id, service_id value and timebucket etc. In most cases, these fields are enough to query a metric. However, sometimes we need to add more fields to the metrics to make the query more flexible. A typical case is the topN query, when we query the top N services by the metric value. If we want to filter the services by Layer or Group or other specific conditions, it is impossible to do this with the current metrics fields.

Since 10.2.0, SkyWalking supports the metrics attributes through source decorate. SkyWalking provides additional attributes(attr0...attr5) fields to the metrics and source. By default, these fields are empty, we can fill them by set a specific decorate logic for source. According to the difference between the OAL and MAL, the usage of decorate is different.

Notice: For now, the metrics attributes only support the service metrics and non-labeled metrics.

OAL Source Decorate

In the OAL script, you can use the decorator function to specify a Java Class to decorate the source, and the Java Class must follow the following rules:

  • The Class must implement the ISourceDecorator interface.
  • The Class package must be under the org.apache.skywalking.*.

Default Decorator

SkyWalking provides some default implementation of decorator:

  • ServiceDecorator which set the attr0 to the service Layer. The following OAL metrics had been decorated by the ServiceDecorator by default:
// Service scope metrics
service_resp_time = from(Service.latency).longAvg().decorator("ServiceDecorator");
service_sla = from(Service.*).percent(status == true).decorator("ServiceDecorator");
service_cpm = from(Service.*).cpm().decorator("ServiceDecorator");
service_apdex = from(Service.latency).apdex(name, status).decorator("ServiceDecorator");
  • EndpointDecorator which set the attr0 to the endpoint Layer. The following OAL metrics had been decorated by the EndpointDecorator by default:
endpoint_cpm = from(Endpoint.*).cpm().decorator("EndpointDecorator");
endpoint_resp_time = from(Endpoint.latency).longAvg().decorator("EndpointDecorator");
endpoint_sla = from(Endpoint.*).percent(status == true).decorator("EndpointDecorator");
  • K8SServiceDecorator which set the attr0 to the k8s service Layer. The following OAL metrics had been decorated by the K8SServiceDecorator by default:
kubernetes_service_http_call_cpm = from(K8SService.*).filter(detectPoint == DetectPoint.SERVER).filter(type == "protocol").filter(protocol.type == "http").cpm().decorator("K8SServiceDecorator");
kubernetes_service_http_call_time = from(K8SService.protocol.http.latency).filter(detectPoint == DetectPoint.SERVER).filter(type == "protocol").filter(protocol.type == "http").longAvg().decorator("K8SServiceDecorator");
kubernetes_service_http_call_successful_rate = from(K8SService.*).filter(detectPoint == DetectPoint.SERVER).filter(type == "protocol").filter(protocol.type == "http").percent(protocol.success == true).decorator("K8SServiceDecorator");
kubernetes_service_apdex = from(K8SService.protocol.http.latency).filter(detectPoint == DetectPoint.SERVER).filter(type == "protocol").filter(protocol.type == "http").apdex(name, protocol.success).decorator("K8SServiceDecorator");

MAL Source Decorate

In the MAL script, you can use the decorate function to decorate the source, and must follow the following rules:

  • The decorate function must after service() function.
  • Not supported for histogram metrics.
  • Not supported for labeled metrics.

SkyWalking does not provide a default script for MAL, you can refer to the following example to set the attr0 to the service Layer:

  - name: cpu_load1
    exp: (node_load1 * 100).service(['node_identifier_host_name'] , Layer.OS_LINUX).decorate({ me -> me.attr0 = me.layer.name()})