Fix Jaeger exporter to correctly translate span.kind attribute

According to opentracing semantic conventions, span.kind attribute
should be one of the following four values: "server", "client",
"producer", "consumer". The spec does not mention the casing of the
strings but all examples show them in lower case. Moreoever, the
OpenTelemetry collector recognizes these values only when they are
lower case. Today if opentelemetry-python exports a span using the
jaeger exporter to the OpenTelemetry collector, it loses the span.kind
information. Using the debug logger exporter in the collector prints the
following to the screen:

    Span #0
        Trace ID       : 31789e02d79452eaedb72769bed5fac7
        Parent ID      : a6398bc507d8a982
        ID             : 4a00eaa815e69785
        Name           : span
        Kind           : SPAN_KIND_UNSPECIFIED
        Start time     : 2020-11-03 18:06:29.684287 +0530 IST
        End time       : 2020-11-03 18:06:29.684344 +0530 IST
        Status code    : STATUS_CODE_CANCELLED
        Status message :

    Span #1
        Trace ID       : 31789e02d79452eaedb72769bed5fac7
        Parent ID      :
        ID             : a6398bc507d8a982
        Name           : HelloWorldResource.on_get
        Kind           : SPAN_KIND_UNSPECIFIED
        Start time     : 2020-11-03 18:06:29.683881 +0530 IST
        End time       : 2020-11-03 18:06:29.684421 +0530 IST
        Status code    : STATUS_CODE_CANCELLED
        Status message :

After the patch, span kind is correctly understood and represented by
the collector:

    Span #0
        Trace ID       : 8e4aeaa621f7e67c813a9cf26c56a202
        Parent ID      : 13f4cc8db8dfe5b3
        ID             : e8032193bb9dca98
        Name           : span
        Kind           : SPAN_KIND_INTERNAL
        Start time     : 2020-11-03 18:03:39.964796 +0530 IST
        End time       : 2020-11-03 18:03:39.964857 +0530 IST
        Status code    : STATUS_CODE_CANCELLED
        Status message :

    Span #1
        Trace ID       : 8e4aeaa621f7e67c813a9cf26c56a202
        Parent ID      :
        ID             : 13f4cc8db8dfe5b3
        Name           : HelloWorldResource.on_get
        Kind           : SPAN_KIND_SERVER
        Start time     : 2020-11-03 18:03:39.964335 +0530 IST
        End time       : 2020-11-03 18:03:39.964936 +0530 IST
        Status code    : STATUS_CODE_CANCELLED
        Status message :

Author: owais

exporter/opentelemetry-exporter-jaeger/src/opentelemetry/exporter/jaeger/__init__.py

@@ -70,13 +70,21 @@
 from opentelemetry.exporter.jaeger.gen.agent import Agent as agent
 from opentelemetry.exporter.jaeger.gen.jaeger import Collector as jaeger
 from opentelemetry.sdk.trace.export import Span, SpanExporter, SpanExportResult
+from opentelemetry.trace import SpanKind
 from opentelemetry.trace.status import StatusCode
 
 DEFAULT_AGENT_HOST_NAME = "localhost"
 DEFAULT_AGENT_PORT = 6831
 
 UDP_PACKET_MAX_LENGTH = 65000
 
+OTLP_JAEGER_SPAN_KIND = {
+    SpanKind.CLIENT: "client",
+    SpanKind.SERVER: "server",
+    SpanKind.CONSUMER: "consumer",
+    SpanKind.PRODUCER: "producer",
+}
+
 logger = logging.getLogger(__name__)
 
 
@@ -226,7 +234,7 @@ def _translate_to_jaeger(spans: Span):
             [
                 _get_long_tag("status.code", status.status_code.value),
                 _get_string_tag("status.message", status.description),
-                _get_string_tag("span.kind", span.kind.name),
+                _get_string_tag("span.kind", _otlp_to_jaeger_span_kind(span.kind)),
             ]
         )
 
@@ -299,6 +307,13 @@ def _convert_int_to_i64(val):
     return val
 
 
+def _otlp_to_jaeger_span_kind(kind: SpanKind) -> str:
+    jaeger_kind = OTLP_JAEGER_SPAN_KIND.get(kind, "")
+    if not jaeger_kind:
+        jaeger_kind = kind.name.lower()
+    return jaeger_kind
+
+
 def _get_trace_id_low(trace_id):
     return _convert_int_to_i64(trace_id & 0xFFFFFFFFFFFFFFFF)
 

exporter/opentelemetry-exporter-jaeger/tests/test_jaeger_exporter.py

@@ -218,7 +218,7 @@ def test_translate_to_jaeger(self):
             jaeger.Tag(
                 key="span.kind",
                 vType=jaeger.TagType.STRING,
-                vStr=trace_api.SpanKind.INTERNAL.name,
+                vStr="internal",
             ),
         ]
 
@@ -315,7 +315,7 @@ def test_translate_to_jaeger(self):
                     jaeger.Tag(
                         key="span.kind",
                         vType=jaeger.TagType.STRING,
-                        vStr=trace_api.SpanKind.CLIENT.name,
+                        vStr="client",
                     ),
                     jaeger.Tag(
                         key="error", vType=jaeger.TagType.BOOL, vBool=True
@@ -391,7 +391,7 @@ def test_translate_to_jaeger(self):
                     jaeger.Tag(
                         key="span.kind",
                         vType=jaeger.TagType.STRING,
-                        vStr=trace_api.SpanKind.INTERNAL.name,
+                        vStr="internal",
                     ),
                     jaeger.Tag(
                         key="otel.instrumentation_library.name",