[CONFIGURATION] File configuration - spec stability (open-telemetry#3862)

Author: marcalff

CHANGELOG.md

@@ -30,6 +30,9 @@ Increment the:
 * [CODE HEALTH] Fix clang-tidy warnings, part 2
   [#3872](https://github.com/open-telemetry/opentelemetry-cpp/pull/3872)
 
+* [CONFIGURATION] File configuration - spec stability
+  [#3862](https://github.com/open-telemetry/opentelemetry-cpp/pull/3862)
+
 Important changes:
 
 * [BUILD] Revisit EventLogger deprecation
@@ -39,6 +42,13 @@ Important changes:
     plans.
   * Please adjust your application accordingly, to avoid disruption.
 
+* [CONFIGURATION] File configuration - spec stability
+  [#3862](https://github.com/open-telemetry/opentelemetry-cpp/pull/3862)
+
+  * The specification for declarative configuration is now stable.
+  * As a result, environment variable `OTEL_EXPERIMENTAL_CONFIG_FILE`
+    is now renamed to `OTEL_CONFIG_FILE`.
+
 ## [1.25 2026-02-07]
 
 * [RELEASE] Bump main branch to 1.25.0-dev (#3759)

examples/configuration/main.cc

@@ -274,7 +274,7 @@ static void usage(FILE *out)
       "\n"
       "The configuration file used will be:\n"
       "  1) the file provided in the command line\n"
-      "  2) the file provided in environment variable ${OTEL_EXPERIMENTAL_CONFIG_FILE}\n"
+      "  2) the file provided in environment variable ${OTEL_CONFIG_FILE}\n"
       "  3) file config.yaml\n"
       "\n"
       "This utility is also used for functional tests.\n"

sdk/src/configuration/yaml_configuration_parser.cc

@@ -30,7 +30,7 @@ std::unique_ptr<Configuration> YamlConfigurationParser::ParseFile(const std::str
 
   if (input_file.empty())
   {
-    static std::string env_var_name("OTEL_EXPERIMENTAL_CONFIG_FILE");
+    static std::string env_var_name("OTEL_CONFIG_FILE");
     std::string env_var;
     const bool env_exists =
         sdk::common::GetStringEnvironmentVariable(env_var_name.c_str(), env_var);