chore(telemetry): add item for instrumentation config id (#8783)

When enabling library injection remotely through the UI, we'd like to
show which
services have been instrumented as a result. To do this we are proposing
to submit the remote configuration ID that was used to instrument the
service.


[](https://datadoghq.atlassian.net/browse/APMON-887)

## 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`.
- [x] If change touches code that signs or publishes builds or packages,
or handles credentials of any kind, I've requested a review from
`@DataDog/security-design-and-guidance`.

## 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

@@ -422,6 +422,14 @@ def _app_started_event(self, register_app_shutdown=True):
         if register_app_shutdown:
             atexit.register(self.app_shutdown)
 
+        inst_config_id_entry = ("instrumentation_config_id", "", "default")
+        if "DD_INSTRUMENTATION_CONFIG_ID" in os.environ:
+            inst_config_id_entry = (
+                "instrumentation_config_id",
+                os.environ["DD_INSTRUMENTATION_CONFIG_ID"],
+                "env_var",
+            )
+
         self.add_configurations(
             [
                 self._telemetry_entry("_trace_enabled"),
@@ -435,6 +443,7 @@ def _app_started_event(self, register_app_shutdown=True):
                 self._telemetry_entry("trace_http_header_tags"),
                 self._telemetry_entry("tags"),
                 self._telemetry_entry("_tracing_enabled"),
+                inst_config_id_entry,
                 (TELEMETRY_STARTUP_LOGS_ENABLED, config._startup_logs_enabled, "unknown"),
                 (TELEMETRY_DYNAMIC_INSTRUMENTATION_ENABLED, di_config.enabled, "unknown"),
                 (TELEMETRY_EXCEPTION_DEBUGGING_ENABLED, ed_config.enabled, "unknown"),

tests/telemetry/test_writer.py

@@ -146,6 +146,7 @@ def test_app_started_event(telemetry_writer, test_agent_session, mock_time):
                     {"name": "logs_injection_enabled", "origin": "default", "value": "false"},
                     {"name": "trace_tags", "origin": "default", "value": ""},
                     {"name": "tracing_enabled", "origin": "default", "value": "true"},
+                    {"name": "instrumentation_config_id", "origin": "default", "value": ""},
                 ],
                 key=lambda x: x["name"],
             ),
@@ -229,6 +230,7 @@ def test_app_started_event_configuration_override(
     env["DD_TRACE_WRITER_INTERVAL_SECONDS"] = "30"
     env["DD_TRACE_WRITER_REUSE_CONNECTIONS"] = "True"
     env["DD_TAGS"] = "team:apm,component:web"
+    env["DD_INSTRUMENTATION_CONFIG_ID"] = "abcedf123"
     env[env_var] = value
 
     file = tmpdir.join("moon_ears.json")
@@ -314,6 +316,7 @@ def test_app_started_event_configuration_override(
             {"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"],
     )