Envoy defines a gRPC service to emit the metrics, whatever implements this protocol can be used to receive the metrics. SkyWalking has a built-in receiver that implements this protocol so that you can configure Envoy to emit its metrics to SkyWalking.
As an APM system, SkyWalking does not only receive and store the metrics emitted by Envoy, it also analyzes the topology of services and service instances.
Attention: There are two versions of Envoy metrics service protocol up to date, v2 and v3, SkyWalking (8.3.0+) supports both of them.
Envoy can be used with / without Istio's control. This section introduces how to configure the standalone Envoy to send the metrics to SkyWalking.
In order to let Envoy send metrics to SkyWalking, we need to feed Envoy with a configuration which contains stats_sinks that includes envoy.metrics_service. This envoy.metrics_service should be configured as a config.grpc_service entry.
The interesting parts of the config is shown in the config below:
stats_sinks: - name: envoy.metrics_service config: grpc_service: # Note: we can use google_grpc implementation as well. envoy_grpc: cluster_name: service_skywalking static_resources: ... clusters: - name: service_skywalking connect_timeout: 5s type: LOGICAL_DNS http2_protocol_options: {} dns_lookup_family: V4_ONLY lb_policy: ROUND_ROBIN load_assignment: cluster_name: service_skywalking endpoints: - lb_endpoints: - endpoint: address: socket_address: address: skywalking # This is the port where SkyWalking serving the Envoy Metrics Service gRPC stream. port_value: 11800
A more complete static configuration, can be observed here.
Note that Envoy can also be configured dynamically through xDS Protocol.
As mentioned above, SkyWalking also builds the topology of services from the metrics, this is because Envoy also carries the service metadata along with the metrics, to feed the Envoy such metadata, another configuration part is as follows:
node: # ... other configs metadata: LABELS: app: test-app NAME: service-instance-name
Typically, Envoy can be also used under Istio's control, where the configurations are much more simple because Istio composes the configurations for you and sends them to Envoy via xDS Protocol. Istio also automatically injects the metadata such as service name and instance name into the bootstrap configurations.
Under this circumstance, emitting the metrics to SyWalking is as simple as adding the option --set meshConfig.defaultConfig.envoyMetricsService.address=<skywalking.address.port.11800> to Istio install command, for example:
istioctl install -y \ --set profile=demo `# replace the profile as per your need` \ --set meshConfig.defaultConfig.envoyMetricsService.address=<skywalking.address.port.11800> # replace <skywalking.address.port.11800> with your actual SkyWalking OAP address
If you already have Istio installed, you can use the following command to apply the config without re-installing Istio:
istioctl manifest install -y \ --set profile=demo `# replace the profile as per your need` \ --set meshConfig.defaultConfig.envoyMetricsService.address=<skywalking.address.port.11800> # replace <skywalking.address.port.11800> with your actual SkyWalking OAP address
Some Envoy statistics are listed in this list. A sample data that contains identifier can be found here, while the metrics only can be observed here.