Test server dynamic delay

BUILD

@@ -30,6 +30,7 @@ envoy_cc_binary(
     name = "nighthawk_test_server",
     repository = "@envoy",
     deps = [
+        "//source/server:http_dynamic_delay_filter_config",
         "//source/server:http_test_server_filter_config",
         "@envoy//source/exe:envoy_main_entry_lib",
     ],

api/server/response_options.proto

@@ -5,13 +5,31 @@ package nighthawk.server;
 import "google/protobuf/wrappers.proto";
 import "validate/validate.proto";
 import "envoy/api/v2/core/base.proto";
+import "google/protobuf/duration.proto";
 
-// Options that control the test server response.
+message ConcurrencyBasedLinearDelay {
+  // Minimal delay to add to replies.
+  google.protobuf.Duration minimal_delay = 1 [(validate.rules).duration.gte.nanos = 0];
+  // Factor to use when adding latency as concurrency increases.
+  google.protobuf.Duration concurrency_delay_factor = 2 [(validate.rules).duration.gte.nanos = 0];
+}
+
+// Options that control the test server response. Can be provided via request
+// headers as well as via static file-based configuration. In case both are
+// provided, a merge will happen, in which case the header-provided
+// configuration will override.
 message ResponseOptions {
   // List of additional response headers.
   repeated envoy.api.v2.core.HeaderValueOption response_headers = 1;
   // Number of 'a' characters in the the response body.
   uint32 response_body_size = 2 [(validate.rules).uint32 = {lte: 4194304}];
   // If true, then echo request headers in the response body.
   bool echo_request_headers = 3;
+
+  oneof oneof_delay_options {
+    // Static delay duration.
+    google.protobuf.Duration static_delay = 4 [(validate.rules).duration.gte.nanos = 0];
+    // Concurrency based linear delay configuration.
+    ConcurrencyBasedLinearDelay concurrency_based_linear_delay = 5;
+  }
 }

source/server/BUILD

@@ -8,16 +8,53 @@ licenses(["notice"])  # Apache 2
 
 envoy_package()
 
+envoy_cc_library(
+    name = "well_known_headers_lib",
+    hdrs = ["well_known_headers.h"],
+    repository = "@envoy",
+    deps = [
+        "@envoy//source/common/http:headers_lib_with_external_headers",
+        "@envoy//source/common/singleton:const_singleton_with_external_headers",
+    ],
+)
+
+envoy_cc_library(
+    name = "configuration_lib",
+    srcs = ["configuration.cc"],
+    hdrs = ["configuration.h"],
+    repository = "@envoy",
+    deps = [
+        "//api/server:response_options_proto_cc_proto",
+        "@envoy//source/common/protobuf:message_validator_lib_with_external_headers",
+        "@envoy//source/common/protobuf:utility_lib_with_external_headers",
+        "@envoy//source/common/singleton:const_singleton_with_external_headers",
+    ],
+)
+
 envoy_cc_library(
     name = "http_test_server_filter_lib",
     srcs = ["http_test_server_filter.cc"],
     hdrs = ["http_test_server_filter.h"],
     repository = "@envoy",
     deps = [
+        ":configuration_lib",
+        ":well_known_headers_lib",
+        "//api/server:response_options_proto_cc_proto",
+        "@envoy//source/exe:envoy_common_lib_with_external_headers",
+    ],
+)
+
+envoy_cc_library(
+    name = "http_dynamic_delay_filter_lib",
+    srcs = ["http_dynamic_delay_filter.cc"],
+    hdrs = ["http_dynamic_delay_filter.h"],
+    repository = "@envoy",
+    deps = [
+        ":configuration_lib",
+        ":well_known_headers_lib",
         "//api/server:response_options_proto_cc_proto",
-        "@envoy//source/common/protobuf:message_validator_lib_with_external_headers",
-        "@envoy//source/common/protobuf:utility_lib_with_external_headers",
         "@envoy//source/exe:envoy_common_lib_with_external_headers",
+        "@envoy//source/extensions/filters/http/fault:fault_filter_lib",
     ],
 )
 
@@ -30,3 +67,13 @@ envoy_cc_library(
         "@envoy//include/envoy/server:filter_config_interface_with_external_headers",
     ],
 )
+
+envoy_cc_library(
+    name = "http_dynamic_delay_filter_config",
+    srcs = ["http_dynamic_delay_filter_config.cc"],
+    repository = "@envoy",
+    deps = [
+        ":http_dynamic_delay_filter_lib",
+        "@envoy//include/envoy/server:filter_config_interface_with_external_headers",
+    ],
+)

source/server/README.md

@@ -16,48 +16,46 @@ bazel build -c opt :nighthawk_test_server
 
 ## Configuring the test server
 
-
 `test-server.yaml` sample content
 
 ```yaml
 static_resources:
   listeners:
-  # define an origin server on :10000 that always returns "lorem ipsum..."
-  - address:
-      socket_address:
-        address: 0.0.0.0
-        port_value: 10000
-    filter_chains:
-    - filters:
-      - name: envoy.http_connection_manager
-        config:
-          generate_request_id: false
-          codec_type: auto
-          stat_prefix: ingress_http
-          route_config:
-            name: local_route
-            virtual_hosts:
-            - name: service
-              domains:
-              - "*"
-          http_filters:
-          - name: envoy.fault
-            config:
-              max_active_faults: 100
-              delay:
-                header_delay: {}
-                percentage:
-                  numerator: 100
-          - name: test-server   # before envoy.router because order matters!
-            config:
-              response_body_size: 10
-              response_headers:
-              - { header: { key: "foo", value: "bar"} }
-              - { header: { key: "foo", value: "bar2"}, append: true }
-              - { header: { key: "x-nh", value: "1"}}
-          - name: envoy.router
-            config:
-              dynamic_stats: false
+    # define an origin server on :10000 that always returns "lorem ipsum..."
+    - address:
+        socket_address:
+          address: 0.0.0.0
+          port_value: 10000
+      filter_chains:
+        - filters:
+            - name: envoy.http_connection_manager
+              config:
+                generate_request_id: false
+                codec_type: auto
+                stat_prefix: ingress_http
+                route_config:
+                  name: local_route
+                  virtual_hosts:
+                    - name: service
+                      domains:
+                        - "*"
+                http_filters:
+                  - name: dynamic-delay
+                    config:
+                      static_delay: 0.5s
+                  - name: test-server # before envoy.router because order matters!
+                    config:
+                      response_body_size: 10
+                      response_headers:
+                        - { header: { key: "foo", value: "bar" } }
+                        - {
+                            header: { key: "foo", value: "bar2" },
+                            append: true,
+                          }
+                        - { header: { key: "x-nh", value: "1" } }
+                  - name: envoy.router
+                    config:
+                      dynamic_stats: false
 admin:
   access_log_path: /tmp/envoy.log
   address:
@@ -68,21 +66,23 @@ admin:
 
 ## Response Options config
 
-The ResponseOptions proto can be used in the test-server filter config or passed in `x-nighthawk-test-server-config``
-request header.
+The [ResponseOptions proto](/api/server/response_options.proto) is shared by
+the `Test Server` and `Dynamic Delay` filter extensions. Each filter will
+interpret the parts that are relevant to it. This allows specifying what
+a response should look like in a single message, which can be done at request
+time via the optional `x-nighthawk-test-server-config` request-header.
 
-The following parameters are available:
+### Test Server
 
-* `response_body_size` - number of 'a' characters repeated in the response body.
-* `response_headers` - list of headers to add to response. If `append` is set to
+- `response_body_size` - number of 'a' characters repeated in the response body.
+- `response_headers` - list of headers to add to response. If `append` is set to
   `true`, then the header is appended.
-* `echo_request_headers` - if set to `true`, then append the dump of request headers to the response
+- `echo_request_headers` - if set to `true`, then append the dump of request headers to the response
   body.
 
-The response options could be used to test and debug proxy or server configuration, for
-example, to verify request headers that are added by intermediate proxy:
+The response options above could be used to test and debug proxy or server configuration, for example, to verify request headers that are added by intermediate proxy:
 
-```
+```bash
 $ curl -6 -v [::1]:8080/nighthawk
 
 *   Trying ::1:8080...
@@ -122,15 +122,28 @@ Request Headers:
 This example shows that intermediate proxy has added `x-forwarded-proto` and
 `x-forwarded-for` request headers.
 
-## Running the test server
+### Dynamic Delay
+
+The Dynamic Delay interprets the `oneof_delay_options` part in the [ResponseOptions proto](/api/server/response_options.proto). If specified, it can be used to:
 
+- Configure a static delay via `static_delay`.
+- Configure a delay which linearly increase as the number of active requests grows, representing a simplified model of an overloaded server, via `concurrency_based_linear_delay`.
+
+All delays have a millisecond-level granularity.
+
+At the time of writing this, there is a [known issue](https://github.com/envoyproxy/nighthawk/issues/392) with merging configuration provided via
+request headers into the statically configured configuration. The current recommendation is to
+use either static, or dynamic configuration (delivered per request header), but not both at the
+same time.
+
+## Running the test server
 
 ```
 # If you already have Envoy running, you might need to set --base-id to allow the test-server to start.
 ➜ /bazel-bin/nighthawk/source/server/server --config-path /path/to/test-server-server.yaml
 
 # Verify the test server with a curl command similar to:
-➜ curl -H "x-envoy-fault-delay-request: 1000" -H "x-nighthawk-test-server-config: {response_body_size:20}"  -vv 127.0.0.1:10000
+➜ curl -H "x-nighthawk-test-server-config: {response_body_size:20, static_delay: \"0s\"}" -vv 127.0.0.1:10000
 ```
 
 ```bash

source/server/configuration.cc

@@ -0,0 +1,45 @@
+#include "server/configuration.h"
+
+#include <string>
+
+#include "external/envoy/source/common/protobuf/message_validator_impl.h"
+#include "external/envoy/source/common/protobuf/utility.h"
+
+#include "api/server/response_options.pb.validate.h"
+
+#include "absl/strings/numbers.h"
+
+namespace Nighthawk {
+namespace Server {
+namespace Configuration {
+
+bool mergeJsonConfig(absl::string_view json, nighthawk::server::ResponseOptions& config,
+                     std::string& error_message) {
+  error_message = "";
+  try {
+    nighthawk::server::ResponseOptions json_config;
+    auto& validation_visitor = Envoy::ProtobufMessage::getStrictValidationVisitor();
+    Envoy::MessageUtil::loadFromJson(std::string(json), json_config, validation_visitor);
+    config.MergeFrom(json_config);
+    Envoy::MessageUtil::validate(config, validation_visitor);
+  } catch (const Envoy::EnvoyException& exception) {
+    error_message = fmt::format("Error merging json config: {}", exception.what());
+  }
+  return error_message == "";
+}
+
+void applyConfigToResponseHeaders(Envoy::Http::ResponseHeaderMap& response_headers,
+                                  nighthawk::server::ResponseOptions& response_options) {
+  for (const auto& header_value_option : response_options.response_headers()) {
+    const auto& header = header_value_option.header();
+    auto lower_case_key = Envoy::Http::LowerCaseString(header.key());
+    if (!header_value_option.append().value()) {
+      response_headers.remove(lower_case_key);
+    }
+    response_headers.addCopy(lower_case_key, header.value());
+  }
+}
+
+} // namespace Configuration
+} // namespace Server
+} // namespace Nighthawk

source/server/configuration.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <string>
+
+#include "envoy/http/header_map.h"
+
+#include "api/server/response_options.pb.h"
+
+namespace Nighthawk {
+namespace Server {
+namespace Configuration {
+
+/**
+ * Merges a json string containing configuration into a ResponseOptions instance.
+ *
+ * @param json Json-formatted seralization of ResponseOptions to merge into the configuration.
+ * @param config The target that the json string should be merged into.
+ * @param error_message Set to an error message if one occurred, else set to an empty string.
+ * @return bool false if an error occurred.
+ */
+bool mergeJsonConfig(absl::string_view json, nighthawk::server::ResponseOptions& config,
+                     std::string& error_message);
+
+/**
+ * Applies ResponseOptions onto a HeaderMap containing response headers.
+ *
+ * @param response_headers Response headers to transform to reflect the passed in response
+ * options.
+ * @param response_options Configuration specifying how to transform the header map.
+ */
+void applyConfigToResponseHeaders(Envoy::Http::ResponseHeaderMap& response_headers,
+                                  nighthawk::server::ResponseOptions& response_options);
+
+} // namespace Configuration
+} // namespace Server
+} // namespace Nighthawk