chore(rcm): payload logging (#7603)

We add a private environment variable to enable logging of the remote
configuration client request and response payloads. This is intended to
be used to debug issues involving the RCM payloads in the client
library.

## 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)
- [ ] If this PR touches code that signs or publishes builds or
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- [ ] This PR doesn't touch any of that.

Author: P403n1x87

ddtrace/internal/remoteconfig/client.py

@@ -16,6 +16,7 @@
 
 import attr
 import cattr
+from envier import En
 import six
 
 import ddtrace
@@ -46,6 +47,15 @@
 TARGET_FORMAT = re.compile(r"^(datadog/\d+|employee)/([^/]+)/([^/]+)/([^/]+)$")
 
 
+class RemoteConfigClientConfig(En):
+    __prefix__ = "_dd.remote_configuration"
+
+    log_payloads = En.v(bool, "log_payloads", default=False)
+
+
+config = RemoteConfigClientConfig()
+
+
 class RemoteConfigError(Exception):
     """
     An error occurred during the configuration update procedure.
@@ -275,10 +285,19 @@ def _send_request(self, payload):
             log.debug(
                 "[%s][P: %s] Requesting RC data from products: %s", os.getpid(), os.getppid(), str(self._products)
             )  # noqa: G200
+
+            if config.log_payloads:
+                log.debug("[%s][P: %s] RC request payload: %s", os.getpid(), os.getppid(), payload)  # noqa: G200
+
             conn = agent.get_connection(self.agent_url, timeout=ddtrace.config._agent_timeout_seconds)
             conn.request("POST", REMOTE_CONFIG_AGENT_ENDPOINT, payload, self._headers)
             resp = conn.getresponse()
             data = resp.read()
+
+            if config.log_payloads:
+                log.debug(
+                    "[%s][P: %s] RC response payload: %s", os.getpid(), os.getppid(), data.decode("utf-8")
+                )  # noqa: G200
         except OSError as e:
             log.debug("Unexpected connection error in remote config client request: %s", str(e))  # noqa: G200
             return None