Add overload manager to bootstrap config (#4038)

Initialize on startup and add documentation (issue #373)

Risk Level: low
Testing: unit tests
Docs Changes: add docs for overload manager

Signed-off-by: Elisha Ziskind <eziskind@google.com>

Mirrored from https://github.com/envoyproxy/envoy @ 14140ad83293d2cb4fcf356064ed98c3bffa295b

docs/BUILD

@@ -55,6 +55,7 @@ proto_library(
         "//envoy/config/metrics/v2:stats",
         "//envoy/config/ratelimit/v2:rls",
         "//envoy/config/rbac/v2alpha:rbac",
+        "//envoy/config/resource_monitor/fixed_heap/v2alpha:fixed_heap",
         "//envoy/config/trace/v2:trace",
         "//envoy/config/transport_socket/capture/v2alpha:capture",
         "//envoy/data/accesslog/v2:accesslog",

envoy/config/bootstrap/v2/BUILD

@@ -15,6 +15,7 @@ api_proto_library_internal(
         "//envoy/api/v2/core:config_source",
         "//envoy/config/metrics/v2:metrics_service",
         "//envoy/config/metrics/v2:stats",
+        "//envoy/config/overload/v2alpha:overload",
         "//envoy/config/ratelimit/v2:rls",
         "//envoy/config/trace/v2:trace",
     ],
@@ -32,6 +33,7 @@ api_go_proto_library(
         "//envoy/api/v2/core:config_source_go_proto",
         "//envoy/config/metrics/v2:metrics_service_go_proto",
         "//envoy/config/metrics/v2:stats_go_proto",
+        "//envoy/config/overload/v2alpha:overload_go_proto",
         "//envoy/config/ratelimit/v2:rls_go_grpc",
         "//envoy/config/trace/v2:trace_go_proto",
     ],

envoy/config/bootstrap/v2/bootstrap.proto

@@ -16,6 +16,7 @@ import "envoy/api/v2/cds.proto";
 import "envoy/api/v2/lds.proto";
 import "envoy/config/trace/v2/trace.proto";
 import "envoy/config/metrics/v2/stats.proto";
+import "envoy/config/overload/v2alpha/overload.proto";
 import "envoy/config/ratelimit/v2/rls.proto";
 
 import "google/protobuf/duration.proto";
@@ -123,6 +124,9 @@ message Bootstrap {
 
   // Configuration for the local administration HTTP server.
   Admin admin = 12 [(validate.rules).message.required = true, (gogoproto.nullable) = false];
+
+  // Optional overload manager configuration.
+  envoy.config.overload.v2alpha.OverloadManager overload_manager = 15;
 }
 
 // Administration interface :ref:`operations documentation

envoy/config/overload/v2alpha/BUILD

@@ -1,8 +1,14 @@
-load("//bazel:api_build_system.bzl", "api_proto_library_internal")
+load("//bazel:api_build_system.bzl", "api_go_proto_library", "api_proto_library_internal")
 
 licenses(["notice"])  # Apache 2
 
 api_proto_library_internal(
     name = "overload",
     srcs = ["overload.proto"],
+    visibility = ["//visibility:public"],
+)
+
+api_go_proto_library(
+    name = "overload",
+    proto = ":overload",
 )

envoy/config/overload/v2alpha/overload.proto

@@ -8,15 +8,19 @@ import "google/protobuf/struct.proto";
 
 import "validate/validate.proto";
 
-// The Overload Manager provides an extensible framework to protect Envoy instances
-// from overload of various resources (memory, cpu, file descriptors, etc)
+// [#protodoc-title: Overload Manager]
 
-message EmptyConfig {
-}
+// The Overload Manager provides an extensible framework to protect Envoy instances
+// from overload of various resources (memory, cpu, file descriptors, etc).
+// It monitors a configurable set of resources and notifies registered listeners
+// when triggers related to those resources fire.
 
 message ResourceMonitor {
   // The name of the resource monitor to instantiate. Must match a registered
-  // resource monitor type.
+  // resource monitor type. The built-in resource monitors are:
+  //
+  // * :ref:`envoy.resource_monitors.fixed_heap
+  //   <envoy_api_msg_config.resource_monitor.fixed_heap.v2alpha.FixedHeapConfig>`
   string name = 1 [(validate.rules).string.min_bytes = 1];
 
   // Configuration for the resource monitor being instantiated.
@@ -45,7 +49,7 @@ message OverloadAction {
   // DNS to ensure uniqueness.
   string name = 1 [(validate.rules).string.min_bytes = 1];
 
-  // A set of triggers for this action. If any of these triggers fires the overload action
+  // A set of triggers for this action. If any of these triggers fire the overload action
   // is activated. Listeners are notified when the overload action transitions from
   // inactivated to activated, or vice versa.
   repeated Trigger triggers = 2 [(validate.rules).repeated .min_items = 1];
@@ -59,5 +63,5 @@ message OverloadManager {
   repeated ResourceMonitor resource_monitors = 2 [(validate.rules).repeated .min_items = 1];
 
   // The set of overload actions.
-  repeated OverloadAction actions = 3 [(validate.rules).repeated .min_items = 1];
+  repeated OverloadAction actions = 3;
 }

envoy/config/resource_monitor/fixed_heap/v2alpha/BUILD

@@ -5,4 +5,5 @@ licenses(["notice"])  # Apache 2
 api_proto_library_internal(
     name = "fixed_heap",
     srcs = ["fixed_heap.proto"],
+    visibility = ["//visibility:public"],
 )

envoy/config/resource_monitor/fixed_heap/v2alpha/fixed_heap.proto

@@ -3,8 +3,11 @@ syntax = "proto3";
 package envoy.config.resource_monitor.fixed_heap.v2alpha;
 option go_package = "v2alpha";
 
+// [#protodoc-title: Fixed heap]
+
+// The fixed heap resource monitor reports the Envoy process memory pressure, computed as a
+// fraction of currently reserved heap memory divided by a statically configured maximum
+// specified in the FixedHeapConfig.
 message FixedHeapConfig {
-  // Limit of the Envoy process heap size. This is used to calculate heap memory pressure which
-  // is defined as (current heap size)/max_heap_size_bytes.
   uint64 max_heap_size_bytes = 1;
 }