[mdns] Conditionally store services to reduce RAM usage by 200-464 bytes

esphome/components/mdns/__init__.py

@@ -1,6 +1,6 @@
 import esphome.codegen as cg
 from esphome.components.esp32 import add_idf_component
-from esphome.config_helpers import filter_source_files_from_platform
+from esphome.config_helpers import filter_source_files_from_platform, get_logger_level
 import esphome.config_validation as cv
 from esphome.const import (
     CONF_DISABLED,
@@ -125,6 +125,17 @@ def mdns_service(
     )
 
 
+def enable_mdns_storage():
+    """Enable persistent storage of mDNS services in the MDNSComponent.
+
+    Called by external components (like OpenThread) that need access to
+    services after setup() completes via get_services().
+
+    Public API for external components. Do not remove.
+    """
+    cg.add_define("USE_MDNS_STORE_SERVICES")
+
+
 @coroutine_with_priority(CoroPriority.NETWORK_SERVICES)
 async def to_code(config):
     if config[CONF_DISABLED] is True:
@@ -150,6 +161,8 @@ async def to_code(config):
 
     if config[CONF_SERVICES]:
         cg.add_define("USE_MDNS_EXTRA_SERVICES")
+        # Extra services need to be stored persistently
+        enable_mdns_storage()
 
     # Ensure at least 1 service (fallback service)
     cg.add_define("MDNS_SERVICE_COUNT", max(1, service_count))
@@ -171,6 +184,10 @@ async def to_code(config):
     # Ensure at least 1 to avoid zero-size array
     cg.add_define("MDNS_DYNAMIC_TXT_COUNT", max(1, dynamic_txt_count))
 
+    # Enable storage if verbose logging is enabled (for dump_config)
+    if get_logger_level() in ("VERBOSE", "VERY_VERBOSE"):
+        enable_mdns_storage()
+
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
 

esphome/components/mdns/mdns_component.cpp

@@ -36,7 +36,7 @@ MDNS_STATIC_CONST_CHAR(SERVICE_TCP, "_tcp");
 // Wrap build-time defines into flash storage
 MDNS_STATIC_CONST_CHAR(VALUE_VERSION, ESPHOME_VERSION);
 
-void MDNSComponent::compile_records_() {
+void MDNSComponent::compile_records_(StaticVector<MDNSService, MDNS_SERVICE_COUNT> &services) {
   this->hostname_ = App.get_name();
 
   // IMPORTANT: The #ifdef blocks below must match COMPONENTS_WITH_MDNS_SERVICES
@@ -53,7 +53,7 @@ void MDNSComponent::compile_records_() {
   MDNS_STATIC_CONST_CHAR(VALUE_BOARD, ESPHOME_BOARD);
 
   if (api::global_api_server != nullptr) {
-    auto &service = this->services_.emplace_next();
+    auto &service = services.emplace_next();
     service.service_type = MDNS_STR(SERVICE_ESPHOMELIB);
     service.proto = MDNS_STR(SERVICE_TCP);
     service.port = api::global_api_server->get_port();
@@ -146,7 +146,7 @@ void MDNSComponent::compile_records_() {
 #ifdef USE_PROMETHEUS
   MDNS_STATIC_CONST_CHAR(SERVICE_PROMETHEUS, "_prometheus-http");
 
-  auto &prom_service = this->services_.emplace_next();
+  auto &prom_service = services.emplace_next();
   prom_service.service_type = MDNS_STR(SERVICE_PROMETHEUS);
   prom_service.proto = MDNS_STR(SERVICE_TCP);
   prom_service.port = USE_WEBSERVER_PORT;
@@ -155,7 +155,7 @@ void MDNSComponent::compile_records_() {
 #ifdef USE_WEBSERVER
   MDNS_STATIC_CONST_CHAR(SERVICE_HTTP, "_http");
 
-  auto &web_service = this->services_.emplace_next();
+  auto &web_service = services.emplace_next();
   web_service.service_type = MDNS_STR(SERVICE_HTTP);
   web_service.proto = MDNS_STR(SERVICE_TCP);
   web_service.port = USE_WEBSERVER_PORT;
@@ -167,12 +167,17 @@ void MDNSComponent::compile_records_() {
 
   // Publish "http" service if not using native API or any other services
   // This is just to have *some* mDNS service so that .local resolution works
-  auto &fallback_service = this->services_.emplace_next();
+  auto &fallback_service = services.emplace_next();
   fallback_service.service_type = MDNS_STR(SERVICE_HTTP);
   fallback_service.proto = MDNS_STR(SERVICE_TCP);
   fallback_service.port = USE_WEBSERVER_PORT;
   fallback_service.txt_records.push_back({MDNS_STR(TXT_VERSION), MDNS_STR(VALUE_VERSION)});
 #endif
+
+#ifdef USE_MDNS_STORE_SERVICES
+  // Copy to member variable if storage is enabled (verbose logging, OpenThread, or extra services)
+  this->services_ = services;
+#endif
 }
 
 void MDNSComponent::dump_config() {
@@ -180,7 +185,7 @@ void MDNSComponent::dump_config() {
                 "mDNS:\n"
                 "  Hostname: %s",
                 this->hostname_.c_str());
-#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
+#ifdef USE_MDNS_STORE_SERVICES
   ESP_LOGV(TAG, "  Services:");
   for (const auto &service : this->services_) {
     ESP_LOGV(TAG, "  - %s, %s, %d", MDNS_STR_ARG(service.service_type), MDNS_STR_ARG(service.proto),

esphome/components/mdns/mdns_component.h

@@ -55,7 +55,9 @@ class MDNSComponent : public Component {
   void add_extra_service(MDNSService service) { this->services_.emplace_next() = std::move(service); }
 #endif
 
+#ifdef USE_MDNS_STORE_SERVICES
   const StaticVector<MDNSService, MDNS_SERVICE_COUNT> &get_services() const { return this->services_; }
+#endif
 
   void on_shutdown() override;
 
@@ -71,9 +73,11 @@ class MDNSComponent : public Component {
   StaticVector<std::string, MDNS_DYNAMIC_TXT_COUNT> dynamic_txt_values_;
 
  protected:
+#ifdef USE_MDNS_STORE_SERVICES
   StaticVector<MDNSService, MDNS_SERVICE_COUNT> services_{};
+#endif
   std::string hostname_;
-  void compile_records_();
+  void compile_records_(StaticVector<MDNSService, MDNS_SERVICE_COUNT> &services);
 };
 
 }  // namespace mdns

esphome/components/mdns/mdns_esp32.cpp

@@ -12,7 +12,8 @@ namespace mdns {
 static const char *const TAG = "mdns";
 
 void MDNSComponent::setup() {
-  this->compile_records_();
+  StaticVector<MDNSService, MDNS_SERVICE_COUNT> services;
+  this->compile_records_(services);
 
   esp_err_t err = mdns_init();
   if (err != ESP_OK) {
@@ -24,7 +25,7 @@ void MDNSComponent::setup() {
   mdns_hostname_set(this->hostname_.c_str());
   mdns_instance_name_set(this->hostname_.c_str());
 
-  for (const auto &service : this->services_) {
+  for (const auto &service : services) {
     std::vector<mdns_txt_item_t> txt_records;
     for (const auto &record : service.txt_records) {
       mdns_txt_item_t it{};

esphome/components/mdns/mdns_esp8266.cpp

@@ -12,11 +12,12 @@ namespace esphome {
 namespace mdns {
 
 void MDNSComponent::setup() {
-  this->compile_records_();
+  StaticVector<MDNSService, MDNS_SERVICE_COUNT> services;
+  this->compile_records_(services);
 
   MDNS.begin(this->hostname_.c_str());
 
-  for (const auto &service : this->services_) {
+  for (const auto &service : services) {
     // Strip the leading underscore from the proto and service_type. While it is
     // part of the wire protocol to have an underscore, and for example ESP-IDF
     // expects the underscore to be there, the ESP8266 implementation always adds

esphome/components/mdns/mdns_libretiny.cpp

@@ -12,11 +12,12 @@ namespace esphome {
 namespace mdns {
 
 void MDNSComponent::setup() {
-  this->compile_records_();
+  StaticVector<MDNSService, MDNS_SERVICE_COUNT> services;
+  this->compile_records_(services);
 
   MDNS.begin(this->hostname_.c_str());
 
-  for (const auto &service : this->services_) {
+  for (const auto &service : services) {
     // Strip the leading underscore from the proto and service_type. While it is
     // part of the wire protocol to have an underscore, and for example ESP-IDF
     // expects the underscore to be there, the ESP8266 implementation always adds

esphome/components/mdns/mdns_rp2040.cpp

@@ -12,11 +12,12 @@ namespace esphome {
 namespace mdns {
 
 void MDNSComponent::setup() {
-  this->compile_records_();
+  StaticVector<MDNSService, MDNS_SERVICE_COUNT> services;
+  this->compile_records_(services);
 
   MDNS.begin(this->hostname_.c_str());
 
-  for (const auto &service : this->services_) {
+  for (const auto &service : services) {
     // Strip the leading underscore from the proto and service_type. While it is
     // part of the wire protocol to have an underscore, and for example ESP-IDF
     // expects the underscore to be there, the ESP8266 implementation always adds

esphome/components/openthread/__init__.py

@@ -5,7 +5,7 @@ from esphome.components.esp32 import (
     add_idf_sdkconfig_option,
     only_on_variant,
 )
-from esphome.components.mdns import MDNSComponent
+from esphome.components.mdns import MDNSComponent, enable_mdns_storage
 import esphome.config_validation as cv
 from esphome.const import CONF_CHANNEL, CONF_ENABLE_IPV6, CONF_ID
 import esphome.final_validate as fv
@@ -141,6 +141,9 @@ FINAL_VALIDATE_SCHEMA = _final_validate
 async def to_code(config):
     cg.add_define("USE_OPENTHREAD")
 
+    # OpenThread SRP needs access to mDNS services after setup
+    enable_mdns_storage()
+
     ot = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(ot, config)
 

esphome/core/defines.h

@@ -83,6 +83,7 @@
 #define USE_LVGL_TILEVIEW
 #define USE_LVGL_TOUCHSCREEN
 #define USE_MDNS
+#define USE_MDNS_STORE_SERVICES
 #define MDNS_SERVICE_COUNT 3
 #define MDNS_DYNAMIC_TXT_COUNT 3
 #define USE_MEDIA_PLAYER