chore(telemetry): remove _trace_enabled config option (#9164)

This change removes the redundant `_trace_enabled` configuration option
from `settings.config`. It was only used in the instrumentation
telemetry writer and its functionality is fully duplicated by the
`_tracing_enabled` option.

Existing tests cover this change.

## Checklist

- [x] Change(s) are motivated and described in the PR description
- [x] Testing strategy is described if automated tests are not included
in the PR
- [x] Risks are described (performance impact, potential for breakage,
maintainability)
- [x] Change is maintainable (easy to change, telemetry, documentation)
- [x] [Library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
are followed or label `changelog/no-changelog` is set
- [x] Documentation is included (in-code, generated user docs, [public
corp docs](https://github.com/DataDog/documentation/))
- [x] Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))
- [x] If this PR changes the public interface, I've notified
`@DataDog/apm-tees`.

## Reviewer Checklist

- [x] Title is accurate
- [x] All changes are related to the pull request's stated goal
- [x] Description motivates each change
- [x] Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- [x] Testing strategy adequately addresses listed risks
- [x] Change is maintainable (easy to change, telemetry, documentation)
- [x] Release note makes sense to a user of the library
- [x] Author has acknowledged and discussed the performance implications
of this PR as reported in the benchmarks PR comment
- [x] Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

ddtrace/internal/telemetry/writer.py

@@ -370,10 +370,7 @@ def add_configs_changed(self, cfg_names):
 
     def _telemetry_entry(self, cfg_name: str) -> Tuple[str, str, _ConfigSource]:
         item = config._config[cfg_name]
-        if cfg_name == "_trace_enabled":
-            name = "trace_enabled"
-            value = "true" if item.value() else "false"
-        elif cfg_name == "_profiling_enabled":
+        if cfg_name == "_profiling_enabled":
             name = "profiling_enabled"
             value = "true" if item.value() else "false"
         elif cfg_name == "_asm_enabled":
@@ -398,7 +395,7 @@ def _telemetry_entry(self, cfg_name: str) -> Tuple[str, str, _ConfigSource]:
             name = "trace_tags"
             value = ",".join(":".join(x) for x in item.value().items())
         elif cfg_name == "_tracing_enabled":
-            name = "tracing_enabled"
+            name = "trace_enabled"
             value = "true" if item.value() else "false"
         elif cfg_name == "_sca_enabled":
             name = "DD_APPSEC_SCA_ENABLED"
@@ -432,7 +429,6 @@ def _app_started_event(self, register_app_shutdown=True):
 
         self.add_configurations(
             [
-                self._telemetry_entry("_trace_enabled"),
                 self._telemetry_entry("_profiling_enabled"),
                 self._telemetry_entry("_asm_enabled"),
                 self._telemetry_entry("_sca_enabled"),

ddtrace/settings/config.py

@@ -273,11 +273,6 @@ def _parse_global_tags(s):
 def _default_config():
     # type: () -> Dict[str, _ConfigItem]
     return {
-        "_trace_enabled": _ConfigItem(
-            name="trace_enabled",
-            default=True,
-            envs=[("DD_TRACE_ENABLED", asbool)],
-        ),
         "_trace_sample_rate": _ConfigItem(
             name="trace_sample_rate",
             default=1.0,

tests/integration/test_settings.py

@@ -59,8 +59,8 @@ def test_setting_origin_environment(test_agent_session, run_python_code_in_subpr
     events_trace_tags = _get_telemetry_config_items(events, "trace_tags")
     assert {"name": "trace_tags", "value": "team:apm,component:web", "origin": "env_var"} in events_trace_tags
 
-    events_tracing_enabled = _get_telemetry_config_items(events, "tracing_enabled")
-    assert {"name": "tracing_enabled", "value": "true", "origin": "env_var"} in events_tracing_enabled
+    events_tracing_enabled = _get_telemetry_config_items(events, "trace_enabled")
+    assert {"name": "trace_enabled", "value": "true", "origin": "env_var"} in events_tracing_enabled
 
 
 @pytest.mark.skipif(AGENT_VERSION != "testagent", reason="Tests only compatible with a testagent")
@@ -122,9 +122,9 @@ def test_setting_origin_code(test_agent_session, run_python_code_in_subprocess):
         "origin": "code",
     } in events_trace_tags
 
-    events_tracing_enabled = _get_telemetry_config_items(events, "tracing_enabled")
+    events_tracing_enabled = _get_telemetry_config_items(events, "trace_enabled")
     assert {
-        "name": "tracing_enabled",
+        "name": "trace_enabled",
         "value": "false",
         "origin": "code",
     } in events_tracing_enabled

tests/telemetry/test_writer.py

@@ -136,7 +136,6 @@ def test_app_started_event(telemetry_writer, test_agent_session, mock_time):
                     {"name": "DD_TRACE_WRITER_REUSE_CONNECTIONS", "origin": "unknown", "value": False},
                     {"name": "ddtrace_auto_used", "origin": "unknown", "value": False},
                     {"name": "ddtrace_bootstrapped", "origin": "unknown", "value": False},
-                    {"name": "trace_enabled", "origin": "default", "value": "true"},
                     {"name": "profiling_enabled", "origin": "default", "value": "false"},
                     {"name": "data_streams_enabled", "origin": "default", "value": "false"},
                     {"name": "appsec_enabled", "origin": "default", "value": "false"},
@@ -145,7 +144,7 @@ def test_app_started_event(telemetry_writer, test_agent_session, mock_time):
                     {"name": "trace_header_tags", "origin": "default", "value": ""},
                     {"name": "logs_injection_enabled", "origin": "default", "value": "false"},
                     {"name": "trace_tags", "origin": "default", "value": ""},
-                    {"name": "tracing_enabled", "origin": "default", "value": "true"},
+                    {"name": "trace_enabled", "origin": "default", "value": "true"},
                     {"name": "instrumentation_config_id", "origin": "default", "value": ""},
                 ],
                 key=lambda x: x["name"],
@@ -315,7 +314,6 @@ def test_app_started_event_configuration_override(
             {"name": "logs_injection_enabled", "origin": "env_var", "value": "true"},
             {"name": "trace_header_tags", "origin": "default", "value": ""},
             {"name": "trace_tags", "origin": "env_var", "value": "team:apm,component:web"},
-            {"name": "tracing_enabled", "origin": "env_var", "value": "false"},
             {"name": "instrumentation_config_id", "origin": "env_var", "value": "abcedf123"},
         ],
         key=lambda x: x["name"],