[core] Add support for setting environment variables (#11953)

esphome/const.py

@@ -336,6 +336,7 @@ CONF_ENERGY = "energy"
 CONF_ENTITY_CATEGORY = "entity_category"
 CONF_ENTITY_ID = "entity_id"
 CONF_ENUM_DATAPOINT = "enum_datapoint"
+CONF_ENVIRONMENT_VARIABLES = "environment_variables"
 CONF_EQUATION = "equation"
 CONF_ESP8266_DISABLE_SSL_SUPPORT = "esp8266_disable_ssl_support"
 CONF_ESPHOME = "esphome"

esphome/core/config.py

@@ -17,6 +17,7 @@ from esphome.const import (
     CONF_COMPILE_PROCESS_LIMIT,
     CONF_DEBUG_SCHEDULER,
     CONF_DEVICES,
+    CONF_ENVIRONMENT_VARIABLES,
     CONF_ESPHOME,
     CONF_FRIENDLY_NAME,
     CONF_ID,
@@ -215,6 +216,11 @@ CONFIG_SCHEMA = cv.All(
                     cv.string_strict: cv.Any([cv.string], cv.string),
                 }
             ),
+            cv.Optional(CONF_ENVIRONMENT_VARIABLES, default={}): cv.Schema(
+                {
+                    cv.string_strict: cv.string,
+                }
+            ),
             cv.Optional(CONF_ON_BOOT): automation.validate_automation(
                 {
                     cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(StartupTrigger),
@@ -426,6 +432,12 @@ async def _add_platformio_options(pio_options):
         cg.add_platformio_option(key, val)
 
 
+@coroutine_with_priority(CoroPriority.FINAL)
+async def _add_environment_variables(env_vars: dict[str, str]) -> None:
+    # Set environment variables for the build process
+    os.environ.update(env_vars)
+
+
 @coroutine_with_priority(CoroPriority.AUTOMATION)
 async def _add_automations(config):
     for conf in config.get(CONF_ON_BOOT, []):
@@ -563,6 +575,9 @@ async def to_code(config: ConfigType) -> None:
     if config[CONF_PLATFORMIO_OPTIONS]:
         CORE.add_job(_add_platformio_options, config[CONF_PLATFORMIO_OPTIONS])
 
+    if config[CONF_ENVIRONMENT_VARIABLES]:
+        CORE.add_job(_add_environment_variables, config[CONF_ENVIRONMENT_VARIABLES])
+
     # Process areas
     all_areas: list[dict[str, str | core.ID]] = []
     if CONF_AREA in config:

tests/components/esphome/common.yaml

@@ -2,6 +2,9 @@ esphome:
   debug_scheduler: true
   platformio_options:
     board_build.flash_mode: dio
+  environment_variables:
+    TEST_ENV_VAR: "test_value"
+    BUILD_NUMBER: "12345"
   area:
     id: testing_area
     name: Testing Area