server_interceptors.go

Documentation: github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing

     1  // Copyright 2017 Michal Witkowski. All Rights Reserved.
     2  // See LICENSE for licensing terms.
     3  
     4  package grpc_opentracing
     5  
     6  import (
     7  	"context"
     8  
     9  	"github.com/grpc-ecosystem/go-grpc-middleware"
    10  	"github.com/grpc-ecosystem/go-grpc-middleware/tags"
    11  	"github.com/grpc-ecosystem/go-grpc-middleware/util/metautils"
    12  	"github.com/opentracing/opentracing-go"
    13  	"github.com/opentracing/opentracing-go/ext"
    14  	"github.com/opentracing/opentracing-go/log"
    15  	"google.golang.org/grpc"
    16  	"google.golang.org/grpc/grpclog"
    17  )
    18  
    19  var (
    20  	grpcTag = opentracing.Tag{Key: string(ext.Component), Value: "gRPC"}
    21  )
    22  
    23  // UnaryServerInterceptor returns a new unary server interceptor for OpenTracing.
    24  func UnaryServerInterceptor(opts ...Option) grpc.UnaryServerInterceptor {
    25  	o := evaluateOptions(opts)
    26  	return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
    27  		if o.filterOutFunc != nil && !o.filterOutFunc(ctx, info.FullMethod) {
    28  			return handler(ctx, req)
    29  		}
    30  		opName := info.FullMethod
    31  		if o.opNameFunc != nil {
    32  			opName = o.opNameFunc(info.FullMethod)
    33  		}
    34  		newCtx, serverSpan := newServerSpanFromInbound(ctx, o.tracer, o.traceHeaderName, opName)
    35  		if o.unaryRequestHandlerFunc != nil {
    36  			o.unaryRequestHandlerFunc(serverSpan, req)
    37  		}
    38  		resp, err := handler(newCtx, req)
    39  		finishServerSpan(ctx, serverSpan, err)
    40  		return resp, err
    41  	}
    42  }
    43  
    44  // StreamServerInterceptor returns a new streaming server interceptor for OpenTracing.
    45  func StreamServerInterceptor(opts ...Option) grpc.StreamServerInterceptor {
    46  	o := evaluateOptions(opts)
    47  	return func(srv interface{}, stream grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
    48  		if o.filterOutFunc != nil && !o.filterOutFunc(stream.Context(), info.FullMethod) {
    49  			return handler(srv, stream)
    50  		}
    51  		opName := info.FullMethod
    52  		if o.opNameFunc != nil {
    53  			opName = o.opNameFunc(info.FullMethod)
    54  		}
    55  		newCtx, serverSpan := newServerSpanFromInbound(stream.Context(), o.tracer, o.traceHeaderName, opName)
    56  		wrappedStream := grpc_middleware.WrapServerStream(stream)
    57  		wrappedStream.WrappedContext = newCtx
    58  		err := handler(srv, wrappedStream)
    59  		finishServerSpan(newCtx, serverSpan, err)
    60  		return err
    61  	}
    62  }
    63  
    64  func newServerSpanFromInbound(ctx context.Context, tracer opentracing.Tracer, traceHeaderName, opName string) (context.Context, opentracing.Span) {
    65  	md := metautils.ExtractIncoming(ctx)
    66  	parentSpanContext, err := tracer.Extract(opentracing.HTTPHeaders, metadataTextMap(md))
    67  	if err != nil && err != opentracing.ErrSpanContextNotFound {
    68  		grpclog.Infof("grpc_opentracing: failed parsing trace information: %v", err)
    69  	}
    70  
    71  	serverSpan := tracer.StartSpan(
    72  		opName,
    73  		// this is magical, it attaches the new span to the parent parentSpanContext, and creates an unparented one if empty.
    74  		ext.RPCServerOption(parentSpanContext),
    75  		grpcTag,
    76  	)
    77  
    78  	injectOpentracingIdsToTags(traceHeaderName, serverSpan, grpc_ctxtags.Extract(ctx))
    79  	return opentracing.ContextWithSpan(ctx, serverSpan), serverSpan
    80  }
    81  
    82  func finishServerSpan(ctx context.Context, serverSpan opentracing.Span, err error) {
    83  	// Log context information
    84  	tags := grpc_ctxtags.Extract(ctx)
    85  	for k, v := range tags.Values() {
    86  		// Don't tag errors, log them instead.
    87  		if vErr, ok := v.(error); ok {
    88  			serverSpan.LogKV(k, vErr.Error())
    89  		} else {
    90  			serverSpan.SetTag(k, v)
    91  		}
    92  	}
    93  	if err != nil {
    94  		ext.Error.Set(serverSpan, true)
    95  		serverSpan.LogFields(log.String("event", "error"), log.String("message", err.Error()))
    96  	}
    97  	serverSpan.Finish()
    98  }
    99
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