Metrics Service Support (#220)

Signed-off-by: Rama <ramaraochavali@gmail.com>

README.md

@@ -108,6 +108,7 @@ Unless otherwise stated, the APIs with the same names as v1 APIs have a similar
   endpoints. The health check subset may not be a subset of the Envoy instance's
   EDS endpoints.
 * [Listener Discovery Service (LDS)](api/lds.proto). This new API supports dynamic discovery of the listener configuration (which ports to bind to, TLS details, filter chains, etc.).
+* [Metric Service (MS)](api/metrics_service.proto). This new API allows Envoy to push (stream) metrics forever for servers to consume.
 * [Rate Limit Service (RLS)](api/rls.proto)
 * [Route Discovery Service (RDS)](api/rds.proto).
 * [Secret Discovery Service (SDS)](api/sds.proto).

api/BUILD

@@ -132,6 +132,17 @@ api_proto_library(
     ],
 )
 
+api_proto_library(
+    name = "metrics",
+    srcs = ["metrics_service.proto"],
+    has_services = 1,
+    deps = [
+        ":base",
+        "@promotheus_metrics_model//:client_model_protos_lib",
+    ],
+    require_py = 0,
+)
+
 api_proto_library(
     name = "protocol",
     srcs = ["protocol.proto"],

api/metrics_service.proto

@@ -0,0 +1,40 @@
+syntax = "proto3";
+
+package envoy.api.v2;
+
+import "api/base.proto";
+
+import "google/api/annotations.proto";
+import "metrics.proto";
+
+// Service for streaming metrics to server that consumes the metrics data. It uses Prometheus metric
+// data model as a standard to represent metrics information.
+service MetricsService {
+  // Envoy will connect and send StreamMetricsMessage messages forever. It does not expect any
+  // response to be sent as nothing would be done in the case of failure. 
+  rpc StreamMetrics(stream StreamMetricsMessage) returns (StreamMetricsResponse) {
+  }
+}
+
+message StreamMetricsResponse {}
+
+message StreamMetricsMessage {
+  message Identifier {
+    // The node sending the access log messages over the stream.
+    Node node = 1;
+  }
+
+  // Identifier data effectively is a structured metadata. 
+  // As a performance optimization this will only be sent in the first message on the stream.
+  Identifier identifier = 1;
+
+  // A list of metric entries
+  repeated io.prometheus.client.MetricFamily envoy_metrics = 2;
+}
+
+// Configuration structure.
+message MetricsServiceConfig {
+  // The name of the upstream cluster that hosts the metrics service. The cluster must be
+  // configured in the cluster manager.
+  string cluster_name = 1;
+}

bazel/api_build_system.bzl

@@ -23,7 +23,7 @@ def api_py_proto_library(name, srcs = [], deps = [], has_services = 0):
 
 # TODO(htuch): has_services is currently ignored but will in future support
 # gRPC stub generation.
-def api_proto_library(name, srcs = [], deps = [], has_services = 0):
+def api_proto_library(name, srcs = [], deps = [], has_services = 0, require_py = 1):
     native.proto_library(
         name = name,
         srcs = srcs,
@@ -43,6 +43,7 @@ def api_proto_library(name, srcs = [], deps = [], has_services = 0):
         deps = [name],
         visibility = ["//visibility:public"],
     )
+    if (require_py == 1):
       api_py_proto_library(name, srcs, deps, has_services)
 
 def api_cc_test(name, srcs, proto_deps):

bazel/repositories.bzl

@@ -1,4 +1,5 @@
 GOOGLEAPIS_SHA = "5c6df0cd18c6a429eab739fb711c27f6e1393366" # May 14, 2017
+PROMETHEUS_SHA = "6f3806018612930941127f2a7c6c453ba2c527d2" # Nov 02, 2017
 
 def api_dependencies():
     native.new_http_archive(
@@ -44,3 +45,31 @@ py_proto_library(
 )
         """,
     )
+
+    native.new_http_archive(
+        name = "promotheus_metrics_model",
+        strip_prefix = "client_model-" + PROMETHEUS_SHA,
+        url = "https://github.com/prometheus/client_model/archive/" + PROMETHEUS_SHA + ".tar.gz",
+        build_file_content = """
+
+filegroup(
+    name = "client_model_protos_src",
+    srcs = [
+        "metrics.proto",
+    ],
+    visibility = ["//visibility:public"],
+ )
+
+proto_library(
+    name = "client_model_protos_lib",
+    srcs = [":client_model_protos_src"],
+    visibility = ["//visibility:public"],
+)
+
+cc_proto_library(
+    name = "client_model_protos",
+    deps = [":client_model_protos_lib"],
+    visibility = ["//visibility:public"],
+)
+        """,
+    )

test/build/BUILD

@@ -12,6 +12,7 @@ api_cc_test(
         "//api:eds",
         "//api:hds",
         "//api:lds",
+        "//api:metrics",
         "//api:rds",
         "//api:rls",
     ],

test/build/build_test.cc

@@ -16,6 +16,7 @@ int main(int argc, char *argv[]) {
     "envoy.api.v2.HealthDiscoveryService.StreamHealthCheck",
     "envoy.api.v2.ListenerDiscoveryService.FetchListeners",
     "envoy.api.v2.ListenerDiscoveryService.StreamListeners",
+    "envoy.api.v2.MetricsService.StreamMetrics",
     "envoy.api.v2.RouteDiscoveryService.FetchRoutes",
     "envoy.api.v2.RouteDiscoveryService.StreamRoutes",
     "envoy.api.v2.RateLimitService.ShouldRateLimit",