Make OTEL support optional so that app can successfully load without opentelemetry packages installed

Author: CaseyTa

cohd/app.py

@@ -4,14 +4,18 @@
 from flask_cors import CORS
 from flask_caching import Cache
 
-from opentelemetry.instrumentation.flask import FlaskInstrumentor
-from opentelemetry import trace    
-from opentelemetry.sdk.resources import SERVICE_NAME as telemetery_service_name_key, Resource
-from opentelemetry.sdk.trace import TracerProvider
-from opentelemetry.sdk.trace.export import BatchSpanProcessor
-from opentelemetry.exporter.jaeger.thrift import JaegerExporter
-from opentelemetry.instrumentation.requests import RequestsInstrumentor
-from opentelemetry.instrumentation.pymysql import PyMySQLInstrumentor
+try:
+    from opentelemetry.instrumentation.flask import FlaskInstrumentor
+    from opentelemetry import trace
+    from opentelemetry.sdk.resources import SERVICE_NAME as telemetery_service_name_key, Resource
+    from opentelemetry.sdk.trace import TracerProvider
+    from opentelemetry.sdk.trace.export import BatchSpanProcessor
+    from opentelemetry.exporter.jaeger.thrift import JaegerExporter
+    from opentelemetry.instrumentation.requests import RequestsInstrumentor
+    from opentelemetry.instrumentation.pymysql import PyMySQLInstrumentor
+    OTEL_ENABLED = True
+except ImportError:
+    OTEL_ENABLED = False
 
 #########
 # INITS #
@@ -48,32 +52,33 @@
     }
 })
 
-logging.info('About to instrument app for OTEL')
-# set the service name for our trace provider 
-# this will tag every trace with the service name given
-otel_service_name = app.config.get('OTEL_SERVICE_NAME', 'COHD')
-tp = TracerProvider(
-        resource=Resource.create({telemetery_service_name_key: otel_service_name})
-    )
-# create an exporter to jaeger     
-jaeger_host = app.config.get('JAEGER_HOST', 'jaeger-otel-agent.sri')
-jaeger_port = app.config.get('JAEGER_PORT', 6831)
-deployment_env = app.config.get('DEPLOYMENT_ENV', 'dev')
-jaeger_exporter = JaegerExporter(
-            agent_host_name=jaeger_host,
-            agent_port=jaeger_port,
+if OTEL_ENABLED:
+    logging.info('About to instrument app for OTEL')
+    # set the service name for our trace provider
+    # this will tag every trace with the service name given
+    otel_service_name = app.config.get('OTEL_SERVICE_NAME', 'COHD')
+    tp = TracerProvider(
+            resource=Resource.create({telemetery_service_name_key: otel_service_name})
         )
-# here we use the exporter to export each span in a trace
-tp.add_span_processor(
-    BatchSpanProcessor(jaeger_exporter)
-)
-trace.set_tracer_provider(
-    tp
-)
-otel_excluded_urls = 'health,api/health,api/dev/.*'
-tracer = trace.get_tracer(__name__)
-FlaskInstrumentor().instrument_app(app,
-                                   excluded_urls=otel_excluded_urls)
-RequestsInstrumentor().instrument()
-PyMySQLInstrumentor().instrument()
-logging.info('Finished instrumenting app for OTEL')
+    # create an exporter to jaeger
+    jaeger_host = app.config.get('JAEGER_HOST', 'jaeger-otel-agent.sri')
+    jaeger_port = app.config.get('JAEGER_PORT', 6831)
+    deployment_env = app.config.get('DEPLOYMENT_ENV', 'dev')
+    jaeger_exporter = JaegerExporter(
+                agent_host_name=jaeger_host,
+                agent_port=jaeger_port,
+            )
+    # here we use the exporter to export each span in a trace
+    tp.add_span_processor(
+        BatchSpanProcessor(jaeger_exporter)
+    )
+    trace.set_tracer_provider(
+        tp
+    )
+    otel_excluded_urls = 'health,api/health,api/dev/.*'
+    tracer = trace.get_tracer(__name__)
+    FlaskInstrumentor().instrument_app(app,
+                                       excluded_urls=otel_excluded_urls)
+    RequestsInstrumentor().instrument()
+    PyMySQLInstrumentor().instrument()
+    logging.info('Finished instrumenting app for OTEL')