fix(extra/redisotel): set span.kind attribute to client

According to the opentelemetry specification this should always be set to client for database client
libraries.

I've also removed the SetAttributes call and instead set the attributes during creation of the span.
This is what the library SHOULD be doing according to the opentelemetry api specification.

Author: kristinnardal2

extra/redisotel/go.sum

@@ -33,6 +33,7 @@ github.com/onsi/ginkgo v1.6.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+W
 github.com/onsi/ginkgo v1.12.1/go.mod h1:zj2OWP4+oCPe1qIXoGWkgMRwljMUYCdkwsT2108oapk=
 github.com/onsi/ginkgo v1.16.4 h1:29JGrr5oVBm5ulCWet69zQkzWipVXIol6ygQUe/EzNc=
 github.com/onsi/ginkgo v1.16.4/go.mod h1:dX+/inL/fNMqNlz0e9LfyB9TswhZpCVdJM/Z6Vvnwo0=
+github.com/onsi/ginkgo v1.16.5/go.mod h1:+E8gABHa3K6zRBolWtd+ROzc/U5bkGt0FwiG042wbpU=
 github.com/onsi/gomega v1.7.1/go.mod h1:XdKZgCCFLUoM/7CFJVPcG8C1xQ1AJ0vpAezJrB7JYyY=
 github.com/onsi/gomega v1.10.1/go.mod h1:iN09h71vgCQne3DLsj+A5owkum+a2tYe+TOCB1ybHNo=
 github.com/onsi/gomega v1.16.0 h1:6gjqkI8iiRHMvdccRJM8rVKjCWk6ZIm6FTm3ddIe4/c=

extra/redisotel/redisotel.go

@@ -27,11 +27,16 @@ func (TracingHook) BeforeProcess(ctx context.Context, cmd redis.Cmder) (context.
 		return ctx, nil
 	}
 
-	ctx, span := tracer.Start(ctx, cmd.FullName())
-	span.SetAttributes(
+	attrs := []attribute.KeyValue{
 		attribute.String("db.system", "redis"),
 		attribute.String("db.statement", rediscmd.CmdString(cmd)),
-	)
+	}
+	opts := []trace.SpanStartOption{
+		trace.WithSpanKind(trace.SpanKindClient),
+		trace.WithAttributes(attrs...),
+	}
+
+	ctx, _ = tracer.Start(ctx, cmd.FullName(), opts...)
 
 	return ctx, nil
 }
@@ -52,12 +57,17 @@ func (TracingHook) BeforeProcessPipeline(ctx context.Context, cmds []redis.Cmder
 
 	summary, cmdsString := rediscmd.CmdsString(cmds)
 
-	ctx, span := tracer.Start(ctx, "pipeline "+summary)
-	span.SetAttributes(
+	attrs := []attribute.KeyValue{
 		attribute.String("db.system", "redis"),
 		attribute.Int("db.redis.num_cmd", len(cmds)),
 		attribute.String("db.statement", cmdsString),
-	)
+	}
+	opts := []trace.SpanStartOption{
+		trace.WithSpanKind(trace.SpanKindClient),
+		trace.WithAttributes(attrs...),
+	}
+
+	ctx, _ = tracer.Start(ctx, "pipeline "+summary, opts...)
 
 	return ctx, nil
 }