feat(server): admin port and interface (#709)

* feat(server): admin port and interface

Signed-off-by: Boaz Sade <boaz@dragonflydb.io>

README.md

@@ -143,6 +143,9 @@ In addition, it has Dragonfly specific arguments options:
  * `hz` - key expiry evaluation frequency. Default is 100. Lower frequency uses less cpu when
    idle at the expense of slower eviction rate.
  * `save_schedule` - glob spec for the UTC time to save a snapshot which matches HH:MM (24h time). default: ""
+ * `primary_port_http_enabled` - If true allows accessing http console on main TCP port, default: true
+ * `admin_port` - If set, would enable admin access to console on the assigned port. This supports both HTTP and RESP protocols. default disabled
+ * `admin_bind` - If set, the admin consol TCP connection would be bind the given address. This supports both HTTP and RESP protocols. default any
 
 ### Example Start Script, with popular options:
 

src/facade/dragonfly_connection.cc

@@ -25,7 +25,17 @@
 
 ABSL_FLAG(bool, tcp_nodelay, false,
           "Configures dragonfly connections with socket option TCP_NODELAY");
-ABSL_FLAG(bool, http_admin_console, true, "If true allows accessing http console on main TCP port");
+ABSL_FLAG(bool, primary_port_http_enabled, true,
+          "If true allows accessing http console on main TCP port");
+
+ABSL_FLAG(
+    std::uint16_t, admin_port, 0,
+    "If set, would enable admin access to console on the assigned port. This supports both HTTP "
+    "and RESP protocols");
+ABSL_FLAG(std::string, admin_bind, "",
+          "If set, the admin consol TCP connection would be bind the given address. "
+          "This supports both HTTP and RESP "
+          "protocols");
 
 using namespace util;
 using namespace std;
@@ -326,7 +336,7 @@ void Connection::HandleRequests() {
 #endif
 
   io::Result<bool> http_res{false};
-  if (absl::GetFlag(FLAGS_http_admin_console))
+
   http_res = CheckForHttpProto(peer);
 
   if (http_res) {
@@ -404,6 +414,16 @@ uint32 Connection::GetClientId() const {
 }
 
 io::Result<bool> Connection::CheckForHttpProto(FiberSocketBase* peer) {
+  bool enabled = absl::GetFlag(FLAGS_primary_port_http_enabled);
+  if (!enabled) {
+    uint16_t admin_port = absl::GetFlag(FLAGS_admin_port);
+    // check if this connection is from the admin port, if so, override primary_port_http_enabled
+    LinuxSocketBase* lsb = static_cast<LinuxSocketBase*>(socket_.get());
+    enabled = lsb->LocalEndpoint().port() == admin_port;
+  }
+  if (!enabled) {
+    return false;
+  }
   size_t last_len = 0;
   do {
     auto buf = io_buf_.AppendBuffer();

src/server/dfly_main.cc

@@ -72,6 +72,8 @@ std::string AbslUnparseFlag(const MaxMemoryFlag& flag) {
 ABSL_DECLARE_FLAG(uint32_t, port);
 ABSL_DECLARE_FLAG(uint32_t, dbnum);
 ABSL_DECLARE_FLAG(uint32_t, memcache_port);
+ABSL_DECLARE_FLAG(uint16_t, admin_port);
+ABSL_DECLARE_FLAG(std::string, admin_bind);
 
 ABSL_FLAG(bool, use_large_pages, false, "If true - uses large memory pages for allocations");
 ABSL_FLAG(string, bind, "",
@@ -319,6 +321,25 @@ bool RunEngine(ProactorPool* pool, AcceptServer* acceptor) {
     }
   }
 
+  std::uint16_t admin_port = GetFlag(FLAGS_admin_port);
+  if (admin_port != 0) {
+    const std::string& admin_bind = GetFlag(FLAGS_admin_bind);
+    // Note passing the result of c_str() for empty string in optimized mode don't work, we must
+    // explicitly set this to null in this case
+    const char* interface_addr = admin_bind.empty() ? nullptr : admin_bind.c_str();
+    const std::string printable_addr =
+        absl::StrCat("admin socket ", interface_addr ? interface_addr : "any", ":", admin_port);
+    Listener* admin_listener = new Listener{Protocol::REDIS, &service};
+    error_code ec = acceptor->AddListener(interface_addr, admin_port, admin_listener);
+
+    if (ec) {
+      LOG(ERROR) << "Failed to open " << printable_addr << ", error: " << ec.message();
+      delete admin_listener;
+    } else {
+      LOG(INFO) << "Listening on " << printable_addr;
+    }
+  }
+
   error_code ec = acceptor->AddListener(bind_addr, port, main_listener);
 
   if (ec) {