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

include/envoy/buffer/buffer.h

@@ -164,6 +164,12 @@ class Instance {
    */
   virtual ssize_t search(const void* data, uint64_t size, size_t start) const PURE;
 
+  /**
+   * Construct a flattened string from a buffer.
+   * @return the flattened string.
+   */
+  virtual std::string toString() const PURE;
+
   /**
    * Write the buffer out to a file descriptor.
    * @param fd supplies the descriptor to write to.

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

@@ -92,6 +92,7 @@ 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

@@ -44,6 +44,7 @@ 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

include/envoy/server/instance.h

@@ -6,6 +6,7 @@
 
 #include "envoy/access_log/access_log.h"
 #include "envoy/api/api.h"
+#include "envoy/http/query_params.h"
 #include "envoy/init/init.h"
 #include "envoy/local_info/local_info.h"
 #include "envoy/network/listen_socket.h"
@@ -184,6 +185,23 @@ class Instance {
    * @return the flush interval of stats sinks.
    */
   virtual std::chrono::milliseconds statsFlushInterval() const PURE;
+
+  /**
+   * Defines a callback that is run when an admin request completes..
+   * The first parameter to the function is the response-headers, which
+   * will generally have Content-Type and Status fields.
+   */
+  typedef std::function<void(Http::Code, Http::HeaderMap&, absl::string_view)> AdminResponseHandler;
+
+  /**
+   * Admin requests are generally handled by posting to the 'main' thread, so
+   * a callback must be supplied which will be called when the response is handled.
+   *
+   * @param path The admin request URL path as a string.
+   * @param params map of parameter names and values.
+   */
+  virtual void adminRequest(absl::string_view path, const Http::Utility::QueryParams& params,
+                            absl::string_view method, AdminResponseHandler& response_handler) 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

@@ -85,6 +85,7 @@ class OwnedImpl : public LibEventInstance {
   ssize_t search(const void* data, uint64_t size, size_t start) const override;
   int write(int fd) override;
   void postProcess() override {}
+  std::string toString() const override;
 
   Event::Libevent::BufferPtr& buffer() override { return buffer_; }
 

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",