admin: Add an API on Server to initiate a programmatic admin request.

include/envoy/http/BUILD

@@ -83,3 +83,8 @@ envoy_cc_library(
     name = "protocol_interface",
     hdrs = ["protocol.h"],
 )
+
+envoy_cc_library(
+    name = "query_params_interface",
+    hdrs = ["query_params.h"],
+)

include/envoy/http/query_params.h

@@ -0,0 +1,16 @@
+#include <map>
+#include <string>
+
+namespace Envoy {
+namespace Http {
+namespace Utility {
+
+// TODO(jmarantz): this should probably be a proper class, with methods to serialize
+// using proper formatting. Perhaps similar to
+// https://github.com/apache/incubator-pagespeed-mod/blob/master/pagespeed/kernel/http/query_params.h
+
+typedef std::map<std::string, std::string> QueryParams;
+
+} // namespace Utility
+} // namespace Http
+} // namespace Envoy

include/envoy/server/BUILD

@@ -27,6 +27,7 @@ envoy_cc_library(
         "//include/envoy/http:codes_interface",
         "//include/envoy/http:filter_interface",
         "//include/envoy/http:header_map_interface",
+        "//include/envoy/http:query_params_interface",
         "//include/envoy/network:listen_socket_interface",
     ],
 )
@@ -92,6 +93,7 @@ envoy_cc_library(
         ":options_interface",
         "//include/envoy/access_log:access_log_interface",
         "//include/envoy/api:api_interface",
+        "//include/envoy/http:query_params_interface",
         "//include/envoy/init:init_interface",
         "//include/envoy/local_info:local_info_interface",
         "//include/envoy/ratelimit:ratelimit_interface",

include/envoy/server/admin.h

@@ -8,6 +8,7 @@
 #include "envoy/http/codes.h"
 #include "envoy/http/filter.h"
 #include "envoy/http/header_map.h"
+#include "envoy/http/query_params.h"
 #include "envoy/network/listen_socket.h"
 #include "envoy/server/config_tracker.h"
 
@@ -44,6 +45,7 @@ class AdminStream {
    */
   virtual const Http::HeaderMap& getRequestHeaders() const PURE;
 };
+
 /**
  * This macro is used to add handlers to the Admin HTTP Endpoint. It builds
  * a callback that executes X when the specified admin handler is hit. This macro can be
@@ -108,6 +110,22 @@ class Admin {
    * @return ConfigTracker& tracker for /config_dump endpoint.
    */
   virtual ConfigTracker& getConfigTracker() PURE;
+
+  /**
+   * Executes an admin request with the specified query params. Note: this must
+   * be called from Envoy's main thread.
+   *
+   * @param path the path of the admin URL.
+   * @param param the query-params passed to the admin request handler.
+   * @param method the HTTP method (POST or GET).
+   * @param response_headers populated the the response headers from executing the request,
+   *     most notably content-type.
+   * @param body populated with the response-body from the admin request.
+   * @return Http::Code The HTTP response code from the admin request.
+   */
+  virtual Http::Code request(absl::string_view path, const Http::Utility::QueryParams& params,
+                             absl::string_view method, Http::HeaderMap& response_headers,
+                             std::string& body) PURE;
 };
 
 } // namespace Server

source/common/buffer/buffer_impl.cc

@@ -183,5 +183,22 @@ OwnedImpl::OwnedImpl(const Instance& data) : OwnedImpl() { add(data); }
 
 OwnedImpl::OwnedImpl(const void* data, uint64_t size) : OwnedImpl() { add(data, size); }
 
+std::string OwnedImpl::toString() const {
+  uint64_t num_slices = getRawSlices(nullptr, 0);
+  RawSlice slices[num_slices];
+  getRawSlices(slices, num_slices);
+  size_t len = 0;
+  for (RawSlice& slice : slices) {
+    len += slice.len_;
+  }
+  std::string output;
+  output.reserve(len);
+  for (RawSlice& slice : slices) {
+    output.append(static_cast<const char*>(slice.mem_), slice.len_);
+  }
+
+  return output;
+}
+
 } // namespace Buffer
 } // namespace Envoy

source/common/buffer/buffer_impl.h

@@ -86,6 +86,12 @@ class OwnedImpl : public LibEventInstance {
   int write(int fd) override;
   void postProcess() override {}
 
+  /**
+   * Construct a flattened string from a buffer.
+   * @return the flattened string.
+   */
+  std::string toString() const;
+
   Event::Libevent::BufferPtr& buffer() override { return buffer_; }
 
 private:

source/common/http/BUILD

@@ -243,6 +243,7 @@ envoy_cc_library(
         "//include/envoy/http:codes_interface",
         "//include/envoy/http:filter_interface",
         "//include/envoy/http:header_map_interface",
+        "//include/envoy/http:query_params_interface",
         "//source/common/buffer:buffer_lib",
         "//source/common/common:assert_lib",
         "//source/common/common:empty_string",

source/common/http/utility.cc

@@ -377,5 +377,17 @@ MessagePtr Utility::prepareHeaders(const ::envoy::api::v2::core::HttpUri& http_u
   return message;
 }
 
+// TODO(jmarantz): make QueryParams a real class and put this serializer there,
+// along with proper URL escaping of the name and value.
+std::string Utility::queryParamsToString(const QueryParams& params) {
+  std::string out;
+  std::string delim = "?";
+  for (auto p : params) {
+    absl::StrAppend(&out, delim, p.first, "=", p.second);
+    delim = "&";
+  }
+  return out;
+}
+
 } // namespace Http
 } // namespace Envoy