fix(debugging): ensure dynamic instrumentation enabled (#6618)

With the introduction of exception debugging, the new enablement logic
caused the dynamic instrumentation to not register with the remoteconfig
client when the programmatic API was used, unless
`DD_DYNAMIC_INSTRUMENTATION_ENABLED` is also set. Since this is not the
documented behaviour, we make this fix to align with the expected
behaviour of the programmatic API.

## 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] Risk is outlined (performance impact, potential for breakage,
maintainability, etc).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] [Library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
are followed. If no release note is required, add label
`changelog/no-changelog`.
- [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))

## Reviewer Checklist

- [ ] Title is accurate.
- [ ] No unnecessary changes are introduced.
- [ ] Description motivates each change.
- [ ] Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes unless absolutely necessary.
- [ ] Testing strategy adequately addresses listed risk(s).
- [ ] Change is maintainable (easy to change, telemetry, documentation).
- [ ] Release note makes sense to a user of the library.
- [ ] Reviewer has explicitly acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment.
- [ ] 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/debugging/_debugger.py

@@ -186,6 +186,8 @@ def enable(cls, run_module=False):
 
         log.debug("Enabling %s", cls.__name__)
 
+        di_config.enabled = True
+
         cls.__watchdog__.install()
 
         if di_config.metrics:
@@ -215,6 +217,8 @@ def disable(cls, join=True):
 
         log.debug("Disabling %s", cls.__name__)
 
+        remoteconfig_poller.unregister("LIVE_DEBUGGING")
+
         forksafe.unregister(cls._restart)
         atexit.unregister(cls.disable)
         unregister_post_run_module_hook(cls._on_run_module)
@@ -229,6 +233,8 @@ def disable(cls, join=True):
         if di_config.metrics:
             metrics.disable()
 
+        di_config.enabled = False
+
         log.debug("%s disabled", cls.__name__)
 
     def __init__(self, tracer=None):

releasenotes/notes/fix-di-enable-programmatic-api-2dd583ac87af5451.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    dynamic instrumentation: Fixed the programmatic API to ensure that the
+    dynamic instrumentation service is fully enabled when
+    ``Dynamic Instrumentation.enable()`` is called.

tests/debugging/test_api.py

@@ -1,7 +1,5 @@
 import pytest
 
-from ddtrace.debugging import DynamicInstrumentation
-
 
 @pytest.mark.subprocess(ddtrace_run=True, env=dict(DD_DYNAMIC_INSTRUMENTATION_ENABLED="true"), err=None)
 def test_debugger_enabled_ddtrace_run():
@@ -17,12 +15,20 @@ def test_debugger_disabled_ddtrace_run():
     assert DynamicInstrumentation._instance is None
 
 
+@pytest.mark.subprocess
 def test_debugger_enabled_programmatically():
+    from ddtrace.internal.remoteconfig.worker import remoteconfig_poller
+
+    assert "LIVE_DEBUGGING" not in remoteconfig_poller._client._products
+    from ddtrace.debugging import DynamicInstrumentation
+
     DynamicInstrumentation.enable()
     assert DynamicInstrumentation._instance is not None
+    assert "LIVE_DEBUGGING" in remoteconfig_poller._client._products
 
     DynamicInstrumentation.disable()
     assert DynamicInstrumentation._instance is None
+    assert "LIVE_DEBUGGING" not in remoteconfig_poller._client._products
 
 
 @pytest.mark.subprocess(err=None)