Only set up exporters if providers are properly set (#530)

This PR fixes the issue where DBOS would throw an exception if
`enable_otlp` is set to `True` but the logger/tracer providers weren't
set. Instead of crashing the entire app, it'll log a warning after this
change.

Also fixed an issue where `DBOS.trace` being `None` (when OTLP tracer
wasn't set) could crash the FastAPI app. It should only set the status
code if it can find an active span.

Author: qianl15

dbos/_dbos.py

@@ -1326,11 +1326,10 @@ def step_status(cls) -> Optional[StepStatus]:
             return None
 
     @classproperty
-    def span(cls) -> "Span":
+    def span(cls) -> Optional["Span"]:
         """Return the tracing `Span` associated with the current context."""
         ctx = assert_current_dbos_context()
         span = ctx.get_current_active_span()
-        assert span
         return span
 
     @classproperty

dbos/_fastapi.py

@@ -87,5 +87,6 @@ async def dbos_fastapi_middleware(
                 and not dbos._config["telemetry"]["disable_otlp"]
                 and hasattr(response, "status_code")
             ):
-                DBOS.span.set_attribute("responseCode", response.status_code)
+                if DBOS.span is not None:
+                    DBOS.span.set_attribute("responseCode", response.status_code)
         return response

dbos/_logger.py

@@ -71,6 +71,7 @@ def config_logger(config: "ConfigFile") -> None:
     if not disable_otlp:
 
         from opentelemetry._logs import get_logger_provider, set_logger_provider
+        from opentelemetry._logs._internal import ProxyLoggerProvider
         from opentelemetry.exporter.otlp.proto.http._log_exporter import OTLPLogExporter
         from opentelemetry.sdk._logs import LoggerProvider, LoggingHandler
         from opentelemetry.sdk._logs.export import BatchLogRecordProcessor
@@ -80,7 +81,8 @@ def config_logger(config: "ConfigFile") -> None:
         # Only set up OTLP provider and exporter if endpoints are provided
         log_provider = get_logger_provider()
         if otlp_logs_endpoints is not None and len(otlp_logs_endpoints) > 0:
-            if not isinstance(log_provider, LoggerProvider):
+            if isinstance(log_provider, ProxyLoggerProvider):
+                # Set a real LoggerProvider if it was previously a ProxyLoggerProvider
                 log_provider = LoggerProvider(
                     Resource.create(
                         attributes={
@@ -91,7 +93,7 @@ def config_logger(config: "ConfigFile") -> None:
                 set_logger_provider(log_provider)
 
             for e in otlp_logs_endpoints:
-                log_provider.add_log_record_processor(
+                log_provider.add_log_record_processor(  # type: ignore
                     BatchLogRecordProcessor(
                         OTLPLogExporter(endpoint=e),
                         export_timeout_millis=5000,
@@ -101,10 +103,14 @@ def config_logger(config: "ConfigFile") -> None:
         # Even if no endpoints are provided, we still need a LoggerProvider to create the LoggingHandler
         global _otlp_handler
         if _otlp_handler is None:
-            _otlp_handler = LoggingHandler(logger_provider=log_provider)
-
-            # Direct DBOS logs to OTLP
-            dbos_logger.addHandler(_otlp_handler)
+            if isinstance(log_provider, ProxyLoggerProvider):
+                dbos_logger.warning(
+                    "OTLP is enabled but logger provider not set, skipping log exporter setup."
+                )
+            else:
+                _otlp_handler = LoggingHandler(logger_provider=log_provider)
+                # Direct DBOS logs to OTLP
+                dbos_logger.addHandler(_otlp_handler)
 
     # Attach DBOS-specific attributes to all log entries.
     global _dbos_log_transformer

dbos/_tracer.py

@@ -8,6 +8,7 @@
 from dbos._utils import GlobalParams
 
 from ._dbos_config import ConfigFile
+from ._logger import dbos_logger
 
 if TYPE_CHECKING:
     from ._context import TracedAttributes
@@ -46,7 +47,8 @@ def config(self, config: ConfigFile) -> None:
 
             # Only set up OTLP provider and exporter if endpoints are provided
             if otlp_traces_endpoints is not None and len(otlp_traces_endpoints) > 0:
-                if not isinstance(tracer_provider, TracerProvider):
+                if isinstance(tracer_provider, trace.ProxyTracerProvider):
+                    # Set a real TracerProvider if it was previously a ProxyTracerProvider
                     resource = Resource(
                         attributes={
                             SERVICE_NAME: config["name"],
@@ -61,7 +63,12 @@ def config(self, config: ConfigFile) -> None:
 
                 for e in otlp_traces_endpoints:
                     processor = BatchSpanProcessor(OTLPSpanExporter(endpoint=e))
-                    tracer_provider.add_span_processor(processor)
+                    tracer_provider.add_span_processor(processor)  # type: ignore
+
+            if isinstance(tracer_provider, trace.ProxyTracerProvider):
+                dbos_logger.warning(
+                    "OTLP is enabled but tracer provider not set, skipping trace exporter setup."
+                )
 
     def set_provider(self, provider: "Optional[TracerProvider]") -> None:
         self.provider = provider

tests/test_fastapi.py

@@ -34,6 +34,7 @@ def test_endpoint(var1: str, var2: str) -> str:
     @app.get("/workflow/{var1}/{var2}")
     @DBOS.workflow()
     def test_workflow(var1: str, var2: str) -> str:
+        assert DBOS.span is not None
         DBOS.span.set_attribute("test_key", "test_value")
         res1 = test_transaction(var1)
         res2 = test_step(var2)
@@ -85,6 +86,7 @@ def test_endpoint(var1: str, var2: str) -> str:
 
     @DBOS.workflow()
     def test_workflow(var1: str, var2: str) -> str:
+        assert DBOS.span is not None
         DBOS.span.set_attribute("test_key", "test_value")
         res1 = test_transaction(var1)
         res2 = test_step(var2)