docs: Improve envoy metrics sending setup documentation (#3389)

* Add envoy metrics sending example
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Newline
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Fix
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Tear down note
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Typo
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

docs/en/setup/envoy/config.yaml

+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 admin:
   access_log_path: /tmp/admin_access.log
   address:
@@ -5,6 +21,7 @@ admin:
       protocol: TCP
       address: 127.0.0.1
       port_value: 9901
+
 stats_sinks:
   - name: envoy.metrics_service
     config:
@@ -66,7 +83,8 @@ static_resources:
                   address:
                     socket_address:
                       address: skywalking
-                      port_value: 9001
+                      # This is the port where SkyWalking serving the Envoy Metrics Service gRPC stream.
+                      port_value: 11800
 
     - name: service_google
       connect_timeout: 5s

docs/en/setup/envoy/examples/metrics/Makefile

+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+up:
+	docker-compose up -d
+
+down:
+	docker-compose down
+
+.PHONY: up down

docs/en/setup/envoy/examples/metrics/README.md

+# Sending Envoy Metrics to SkyWalking OAP Server Example
+
+This is an example of sending [Envoy Stats](https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/observability/statistics#arch-overview-statistics) to SkyWalking OAP server
+through [Metric Service](https://www.envoyproxy.io/docs/envoy/latest/api-v2/config/metrics/v2/metrics_service.proto).
+
+## Running the example
+
+The example requires `docker` and `docker-compose` to be installed in your local. It fetches images from Docker Hub.
+
+Note that in ths setup, we override the [`log4j2.xml`](log4j2.xml) config to set the `org.apache.skywalking.oap.server.receiver.envoy` logger level to `DEBUG`. This enables us to see the messages sent by Envoy to SkyWalking OAP server.
+
+```
+$ make up
+$ docker-compose logs -f skywalking
+$ # Please wait for a moment until SkyWalking is ready and Envoy starts sending the stats. You will see similar messages like the following:
+skywalking_1  | 2019-08-31 23:57:40,672 - org.apache.skywalking.oap.server.receiver.envoy.MetricServiceGRPCHandler -26870 [grpc-default-executor-0] DEBUG [] - Received msg identifier {
+skywalking_1  |   node {
+skywalking_1  |     id: "ingress"
+skywalking_1  |     cluster: "envoy-proxy"
+skywalking_1  |     metadata {
+skywalking_1  |       fields {
+skywalking_1  |         key: "skywalking"
+skywalking_1  |         value {
+skywalking_1  |           string_value: "iscool"
+skywalking_1  |         }
+skywalking_1  |       }
+skywalking_1  |       fields {
+skywalking_1  |         key: "envoy"
+skywalking_1  |         value {
+skywalking_1  |           string_value: "isawesome"
+skywalking_1  |         }
+skywalking_1  |       }
+skywalking_1  |     }
+skywalking_1  |     locality {
+skywalking_1  |       region: "ap-southeast-1"
+skywalking_1  |       zone: "zone1"
+skywalking_1  |       sub_zone: "subzone1"
+skywalking_1  |     }
+skywalking_1  |     build_version: "e349fb6139e4b7a59a9a359be0ea45dd61e589c5/1.11.1/Clean/RELEASE/BoringSSL"
+skywalking_1  |   }
+skywalking_1  | }
+skywalking_1  | envoy_metrics {
+skywalking_1  |   name: "cluster.service_skywalking.update_success"
+skywalking_1  |   type: COUNTER
+skywalking_1  |   metric {
+skywalking_1  |     counter {
+skywalking_1  |       value: 2.0
+skywalking_1  |     }
+skywalking_1  |     timestamp_ms: 1567295859556
+skywalking_1  |   }
+skywalking_1  | }
+...
+
+$ # To tear down:
+$ make down
+```

docs/en/setup/envoy/examples/metrics/docker-compose.yaml

+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+version: "3"
+services:
+  envoy:
+    image: envoyproxy/envoy-alpine:latest
+    command: /usr/local/bin/envoy -c /etc/envoy.yaml --service-cluster envoy-proxy
+    ports:
+    - 10000:10000
+    depends_on:
+    - skywalking
+    volumes:
+    - ./envoy.yaml:/etc/envoy.yaml
+
+  skywalking:
+    image: apache/skywalking-oap-server:latest
+    volumes:
+    - ./log4j2.xml:/skywalking/config/log4j2.xml
+    expose:
+    - "11800"

docs/en/setup/envoy/examples/metrics/envoy.yaml

+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+admin:
+  access_log_path: /tmp/admin_access.log
+  address:
+    socket_address:
+      protocol: TCP
+      address: 127.0.0.1
+      port_value: 9901
+
+stats_sinks:
+  - name: envoy.metrics_service
+    config:
+      grpc_service:
+        envoy_grpc:
+          cluster_name: service_skywalking
+
+node:
+  id: ingress
+  cluster: card-api-cluster
+  locality:
+    region: ap-southeast-1
+    zone: zone1
+    sub_zone: subzone1
+  metadata:
+    skywalking: iscool
+    envoy: isawesome
+
+static_resources:
+  listeners:
+    - name: listener_0
+      address:
+        socket_address:
+          protocol: TCP
+          address: 0.0.0.0
+          port_value: 10000
+      filter_chains:
+        - filters:
+            - name: envoy.http_connection_manager
+              typed_config:
+                "@type": type.googleapis.com/envoy.config.filter.network.http_connection_manager.v2.HttpConnectionManager
+                stat_prefix: ingress_http
+                route_config:
+                  name: local_route
+                  virtual_hosts:
+                    - name: local_service
+                      domains: ["*"]
+                      routes:
+                        - match:
+                            prefix: "/"
+                          route:
+                            host_rewrite: www.google.com
+                            cluster: service_google
+                http_filters:
+                  - name: envoy.router
+  clusters:
+    - name: service_skywalking
+      connect_timeout: 5s
+      type: STRICT_DNS
+      http2_protocol_options: {}
+      # Comment out the following line to test on v6 networks
+      dns_lookup_family: V4_ONLY
+      lb_policy: ROUND_ROBIN
+      load_assignment:
+        cluster_name: service_skywalking
+        endpoints:
+          - lb_endpoints:
+              - endpoint:
+                  address:
+                    socket_address:
+                      address: skywalking
+                      port_value: 11800
+
+    - name: service_google
+      connect_timeout: 5s
+      type: STRICT_DNS
+      # Comment out the following line to test on v6 networks
+      dns_lookup_family: V4_ONLY
+      lb_policy: ROUND_ROBIN
+      load_assignment:
+        cluster_name: service_google
+        endpoints:
+          - lb_endpoints:
+              - endpoint:
+                  address:
+                    socket_address:
+                      address: www.google.com
+                      port_value: 443
+      tls_context:
+        sni: www.google.com

docs/en/setup/envoy/examples/metrics/log4j2.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Licensed to the Apache Software Foundation (ASF) under one or more
+  ~ contributor license agreements.  See the NOTICE file distributed with
+  ~ this work for additional information regarding copyright ownership.
+  ~ The ASF licenses this file to You under the Apache License, Version 2.0
+  ~ (the "License"); you may not use this file except in compliance with
+  ~ the License.  You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  ~
+  -->
+
+<Configuration status="INFO">
+    <Appenders>
+        <Console name="Console" target="SYSTEM_OUT">
+            <PatternLayout charset="UTF-8" pattern="%d - %c -%-4r [%t] %-5p %x - %m%n"/>
+        </Console>
+    </Appenders>
+    <Loggers>
+        <logger name="org.eclipse.jetty" level="INFO"/>
+        <logger name="org.apache.zookeeper" level="INFO"/>
+        <logger name="org.elasticsearch.common.network.IfConfig" level="INFO"/>
+        <logger name="io.grpc.netty" level="INFO"/>
+        <logger name="org.apache.skywalking.oap.server.receiver.istio.telemetry" level="DEBUG"/>
+        <!-- We make envoy metrics receiver to log at DEBUG level -->
+        <logger name="org.apache.skywalking.oap.server.receiver.envoy" level="DEBUG"/>
+        <Root level="INFO">
+            <AppenderRef ref="Console"/>
+        </Root>
+    </Loggers>
+</Configuration>