tracer: Add SkyWalking tracer

CODEOWNERS

@@ -48,6 +48,8 @@ extensions/filters/common/original_src @snowp @klarose
 /*/extensions/tracers/datadog @cgilmour @palazzem @mattklein123
 # tracers.xray extension
 /*/extensions/tracers/xray @marcomagdy @lavignes @mattklein123
+# tracers.skywalking extension
+/*/extensions/tracers/skywalking @dio @lizan @wbpcode
 # mysql_proxy extension
 /*/extensions/filters/network/mysql_proxy @rshriram @venilnoronha @mattklein123
 # postgres_proxy extension

api/bazel/repositories.bzl

@@ -37,6 +37,11 @@ def api_dependencies():
         locations = REPOSITORY_LOCATIONS,
         build_file_content = ZIPKINAPI_BUILD_CONTENT,
     )
+    envoy_http_archive(
+        name = "com_github_apache_skywalking_data_collect_protocol",
+        locations = REPOSITORY_LOCATIONS,
+        build_file_content = SKYWALKING_DATA_COLLECT_PROTOCOL_BUILD_CONTENT,
+    )
 
 PROMETHEUSMETRICS_BUILD_CONTENT = """
 load("@envoy_api//bazel:api_build_system.bzl", "api_cc_py_proto_library")
@@ -98,3 +103,17 @@ go_proto_library(
     visibility = ["//visibility:public"],
 )
 """
+
+SKYWALKING_DATA_COLLECT_PROTOCOL_BUILD_CONTENT = """
+load("@com_google_protobuf//:protobuf.bzl", "cc_proto_library")
+cc_proto_library(
+    name = "protocol_cc_proto",
+    srcs = [
+        "common/Common.proto",
+        "language-agent/Tracing.proto",
+    ],
+    default_runtime = "@com_google_protobuf//:protobuf",
+    protoc = "@com_google_protobuf//:protoc",
+    visibility = ["//visibility:public"],
+)
+"""

api/bazel/repository_locations.bzl

@@ -22,6 +22,9 @@ ZIPKINAPI_SHA256 = "688c4fe170821dd589f36ec45aaadc03a618a40283bc1f97da8fa11686fc
 RULES_PROTO_GIT_SHA = "40298556293ae502c66579620a7ce867d5f57311"  # Aug 17, 2020
 RULES_PROTO_SHA256 = "aa1ee19226f707d44bee44c720915199c20c84a23318bb0597ed4e5c873ccbd5"
 
+SKYWALKING_COLLECT_DATA_PROTOCOL_RELEASE = "8.1.0"
+SKYWALKING_COLLECT_DATA_PROTOCOL_SHA256 = "ebea8a6968722524d1bcc4426fb6a29907ddc2902aac7de1559012d3eee90cf9"
+
 REPOSITORY_LOCATIONS = dict(
     bazel_skylib = dict(
         sha256 = BAZEL_SKYLIB_SHA256,
@@ -63,4 +66,9 @@ REPOSITORY_LOCATIONS = dict(
         strip_prefix = "zipkin-api-" + ZIPKINAPI_RELEASE,
         urls = ["https://github.com/openzipkin/zipkin-api/archive/" + ZIPKINAPI_RELEASE + ".tar.gz"],
     ),
+    com_github_apache_skywalking_data_collect_protocol = dict(
+        sha256 = SKYWALKING_COLLECT_DATA_PROTOCOL_SHA256,
+        strip_prefix = "skywalking-data-collect-protocol-" + SKYWALKING_COLLECT_DATA_PROTOCOL_RELEASE,
+        urls = ["https://github.com/apache/skywalking-data-collect-protocol/archive/v" + SKYWALKING_COLLECT_DATA_PROTOCOL_RELEASE + ".tar.gz"],
+    ),
 )

api/envoy/config/trace/v3/skywalking.proto

@@ -0,0 +1,57 @@
+syntax = "proto3";
+
+package envoy.config.trace.v3;
+
+import "envoy/config/core/v3/grpc_service.proto";
+
+import "google/protobuf/wrappers.proto";
+
+import "udpa/annotations/migrate.proto";
+import "udpa/annotations/status.proto";
+import "udpa/annotations/versioning.proto";
+import "validate/validate.proto";
+
+option java_package = "io.envoyproxy.envoy.config.trace.v3";
+option java_outer_classname = "SkywalkingProto";
+option java_multiple_files = true;
+option (udpa.annotations.file_migrate).move_to_package =
+    "envoy.extensions.tracers.skywalking.v4alpha";
+option (udpa.annotations.file_status).package_version_status = ACTIVE;
+
+// [#protodoc-title: SkyWalking tracer]
+
+// Configuration for the SkyWalking tracer.
+// [#extension: envoy.tracers.skywalking]
+message SkyWalkingConfig {
+  // SkyWalking collector service.
+  core.v3.GrpcService grpc_service = 1 [(validate.rules).message = {required: true}];
+
+  ClientConfig client_config = 2;
+}
+
+// Client config for SkyWalking tracer.
+// [#next-free-field: 6]
+message ClientConfig {
+  // Service name for SkyWalking tracer. If service_name is empty, then cluster
+  // name of Envoy will be used as service name.
+  string service_name = 1;
+
+  // Service instance name for SkyWalking tracer. If instance_name is empty, the
+  // node name of Envoy will be used as service instance name.
+  string instance_name = 2;
+
+  // Authentication token. Set client token if backend open token
+  // authentication.
+  string authentication = 3;
+
+  // When this field is set to true and Envoy is not the first tracing node, it
+  // directly uses the downstream endpoint as its own endpoint. This is helpful
+  // when the user wants to use the endpoint to aggregate all span data on the
+  // tracing link.
+  bool pass_endpoint = 4;
+
+  // Envoy caches the segment in memory when the backend service is temporarily
+  // unavailable. This field specifies the maximum number of segments that can
+  // be cached. If not specified, the default is 1024.
+  google.protobuf.UInt32Value max_cache_size = 5;
+}

api/envoy/config/trace/v3/trace.proto

@@ -10,6 +10,7 @@ import public "envoy/config/trace/v3/http_tracer.proto";
 import public "envoy/config/trace/v3/lightstep.proto";
 import public "envoy/config/trace/v3/opencensus.proto";
 import public "envoy/config/trace/v3/service.proto";
+import public "envoy/config/trace/v3/skywalking.proto";
 import public "envoy/config/trace/v3/zipkin.proto";
 
 option java_package = "io.envoyproxy.envoy.config.trace.v3";

source/extensions/extensions_build_config.bzl

@@ -153,6 +153,7 @@ EXTENSIONS = {
     "envoy.tracers.datadog":                            "//source/extensions/tracers/datadog:config",
     "envoy.tracers.zipkin":                             "//source/extensions/tracers/zipkin:config",
     "envoy.tracers.opencensus":                         "//source/extensions/tracers/opencensus:config",
+    "envoy.tracers.skywalking":                         "//source/extensions/tracers/skywalking:config",
     # WiP
     "envoy.tracers.xray":                               "//source/extensions/tracers/xray:config",