Add header matched routing

docs/configuration/http_conn_man/route_config/route.rst

@@ -23,7 +23,8 @@ next (e.g., redirect, forward, rewrite, etc.).
     "retry_policy": "{...}",
     "rate_limit": "{...}",
     "shadow": "{...}",
-    "priority": "..."
+    "priority": "...",
+    "headers": "[]"
   }
 
 prefix
@@ -94,6 +95,9 @@ priority
   *(optional, string)* Optionally specifies the :ref:`routing priority
   <arch_overview_http_routing_priority>`.
 
+:ref:`headers <config_http_conn_man_route_table_route_headers>`
+  *(optional, array)* Specifies a set of headers that the route should match on.
+
 .. _config_http_conn_man_route_table_route_runtime:
 
 Runtime
@@ -197,3 +201,27 @@ runtime_key
   from 0 to 10000, allowing for increments of 0.01% of requests to be shadowed. If the runtime key
   is specified in the configuration but not present in runtime, 0 is the default and thus 0% of
   requests will be shadowed.
+
+.. _config_http_conn_man_route_table_route_headers:
+
+Headers
+-------
+
+The router can match a request to a route based on headers specified in the route config.
+
+.. code-block:: json
+
+  [
+    {"name": "...", "value": "..."}
+  ]
+
+name
+  *(required, string)* Specifies the name of the header in the request.
+
+value
+  *(optional, string)* Specifies the value of the header. If the value is absent a request that has the
+   ``name`` header will match, regardless of the header's value.
+
+The router will check the request's headers against all the specified
+headers in the route config. A match will happen if all the headers in the route are present in
+the request with the same values (or based on presence if the ``value`` field is not in the config).

include/envoy/router/router.h

@@ -154,7 +154,7 @@ class RouteEntry {
    * Do potentially destructive header transforms on request headers prior to forwarding. For
    * example URL prefix rewriting, adding headers, etc. This should only be called ONCE
    * immediately prior to forwarding. It is done this way vs. copying for performance reasons.
-   * @param headers supplise the request headers, which may be modified during this call.
+   * @param headers supplies the request headers, which may be modified during this call.
    */
   virtual void finalizeRequestHeaders(Http::HeaderMap& headers) const PURE;
 

source/common/router/config_impl.cc

@@ -65,6 +65,15 @@ RouteEntryImplBase::RouteEntryImplBase(const VirtualHost& vhost, const Json::Obj
   if (!(isRedirect() ^ !cluster_name_.empty())) {
     throw EnvoyException("routes must be either redirects or cluster targets");
   }
+
+  if (route.hasObject("headers")) {
+    std::vector<Json::Object> config_headers = route.getObjectArray("headers");
+    for (const Json::Object& header_map : config_headers) {
+      // allow header value to be empty, allows matching to be only based on header presence.
+      config_headers_.emplace_back(Http::LowerCaseString(header_map.getString("name")),
+                                   header_map.getString("value", EMPTY_STRING));
+    }
+  }
 }
 
 bool RouteEntryImplBase::matches(const Http::HeaderMap& headers, uint64_t random_value) const {
@@ -79,6 +88,19 @@ bool RouteEntryImplBase::matches(const Http::HeaderMap& headers, uint64_t random
     matches &= (headers.get(Http::Headers::get().ContentType) == content_type_);
   }
 
+  if (!config_headers_.empty()) {
+    for (const HeaderData& header_data : config_headers_) {
+      if (header_data.value_ == EMPTY_STRING) {
+        matches &= headers.has(header_data.name_);
+      } else {
+        matches &= (headers.get(header_data.name_) == header_data.value_);
+      }
+      if (!matches) {
+        break;
+      }
+    }
+  }
+
   return matches;
 }
 

source/common/router/config_impl.h

@@ -194,6 +194,14 @@ class RouteEntryImplBase : public RouteEntry, public Matchable, public RedirectE
     uint64_t default_;
   };
 
+  struct HeaderData {
+    HeaderData(const Http::LowerCaseString& name, const std::string& value)
+        : name_(name), value_(value) {}
+
+    const Http::LowerCaseString name_;
+    const std::string value_;
+  };
+
   static Optional<RuntimeData> loadRuntimeData(const Json::Object& route);
 
   // Default timeout is 15s if nothing is specified in the route config.
@@ -211,6 +219,7 @@ class RouteEntryImplBase : public RouteEntry, public Matchable, public RedirectE
   const RateLimitPolicyImpl rate_limit_policy_;
   const ShadowPolicyImpl shadow_policy_;
   const Upstream::ResourcePriority priority_;
+  std::vector<HeaderData> config_headers_;
 };
 
 /**

test/common/router/config_impl_test.cc

@@ -398,6 +398,84 @@ TEST(RouteMatcherTest, Priority) {
   }
 }
 
+TEST(RouteMatcherTest, HeaderMatchedRouting) {
+  std::string json = R"EOF(
+{
+  "virtual_hosts": [
+    {
+      "name": "local_service",
+      "domains": ["*"],
+      "routes": [
+        {
+          "prefix": "/",
+          "cluster": "local_service_with_headers",
+          "headers" : [
+            {"name": "test_header", "value": "test"}
+          ]
+        },
+        {
+          "prefix": "/",
+          "cluster": "local_service_with_multiple_headers",
+          "headers" : [
+            {"name": "test_header_multiple1", "value": "test1"},
+            {"name": "test_header_multiple2", "value": "test2"}
+          ]
+        },
+        {
+          "prefix": "/",
+          "cluster": "local_service_with_empty_headers",
+          "headers" : [
+            {"name": "test_header_presence"}
+          ]
+        },
+        {
+          "prefix": "/",
+          "cluster": "local_service_without_headers"
+        }
+      ]
+    }
+  ]
+}
+  )EOF";
+
+  Json::StringLoader loader(json);
+  NiceMock<Runtime::MockLoader> runtime;
+  NiceMock<Upstream::MockClusterManager> cm;
+  ConfigImpl config(loader, runtime, cm);
+
+  {
+    EXPECT_EQ("local_service_without_headers",
+              config.routeForRequest(genHeaders("www.lyft.com", "/", "GET"), 0)->clusterName());
+  }
+
+  {
+    Http::HeaderMapImpl headers = genHeaders("www.lyft.com", "/", "GET");
+    headers.addViaCopy("test_header", "test");
+    EXPECT_EQ("local_service_with_headers", config.routeForRequest(headers, 0)->clusterName());
+  }
+
+  {
+    Http::HeaderMapImpl headers = genHeaders("www.lyft.com", "/", "GET");
+    headers.addViaCopy("test_header_multiple1", "test1");
+    headers.addViaCopy("test_header_multiple2", "test2");
+    EXPECT_EQ("local_service_with_multiple_headers",
+              config.routeForRequest(headers, 0)->clusterName());
+  }
+
+  {
+    Http::HeaderMapImpl headers = genHeaders("www.lyft.com", "/", "GET");
+    headers.addViaCopy("non_existent_header", "foo");
+    EXPECT_EQ("local_service_without_headers", config.routeForRequest(headers, 0)->clusterName());
+  }
+
+  {
+    Http::HeaderMapImpl headers = genHeaders("www.lyft.com", "/", "GET");
+    headers.addViaCopy("test_header_presence", "test");
+    EXPECT_EQ("local_service_with_empty_headers",
+              config.routeForRequest(headers, 0)->clusterName());
+  }
+}
+
 TEST(RouteMatcherTest, ContentType) {
   std::string json = R"EOF(
 {