Enable tracing only if a tracing context is provided

Would be nice if we could enable tracing in all cases. But the current timeout and retry
logic of the Opentelemetry SDK does not work as intended, which can lead to longer hanging
executions in case the configured collector (e.g. Jaeger) is not reachable.

For now only enable tracing in case the caller provides a tracing context. This way we produce
traces only when the caller is interested in them.

This condition can be removed once the timeout and retry logic was fixed
(open-telemetry/opentelemetry-python#4043).

Change-Id: Id9ce70cf3232a5e1bbe9497e8c30a568ac693b78

bin/check_mk

@@ -51,11 +51,18 @@ cmk.base.utils.register_sigint_handler()
 
 help_function = modes.get("help").handler_function
 
-
-init_span_processor(
-    trace.init_tracing(omd_site(), "cmk"),
-    exporter_from_config(trace.trace_send_config(get_omd_config(cmk.utils.paths.omd_root))),
-)
+# Would be nice if we could enable tracing in all cases. But the current timeout and retry
+# logic of the Opentelemetry SDK does not work as intended, which can lead to longer hanging
+# executions in case the configured collector (e.g. Jaeger) is not reachable.
+# For now only enable tracing in case the caller provides a tracing context. This way we produce
+# traces only when the caller is interested in them.
+# This condition can be removed once the timeout and retry logic was fixed
+# (https://github.com/open-telemetry/opentelemetry-python/issues/4043).
+if trace_context := trace.extract_context_from_environment(dict(os.environ)):
+    init_span_processor(
+        trace.init_tracing(omd_site(), "cmk"),
+        exporter_from_config(trace.trace_send_config(get_omd_config(cmk.utils.paths.omd_root))),
+    )
 
 
 # We probably don't really need to register that here, do we?
@@ -127,8 +134,6 @@ try:
     if mode_name not in modes.non_config_options():
         config.load()
 
-    trace_context = trace.extract_context_from_environment(dict(os.environ))
-
     done, exit_status = False, 0
     if mode_name is not None and mode_args is not None:
         exit_status = modes.call(mode_name, mode_args, opts, args, trace_context)