github.com/zorawar87/trillian@v1.2.1/monitoring/opencensus/trace.go (about)

     1  // Copyright 2018 Google LLC. All Rights Reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package opencensus
    16  
    17  import (
    18  	"errors"
    19  	"net/http"
    20  
    21  	"contrib.go.opencensus.io/exporter/stackdriver"
    22  	"go.opencensus.io/plugin/ocgrpc"
    23  	"go.opencensus.io/plugin/ochttp"
    24  	"go.opencensus.io/stats/view"
    25  	"go.opencensus.io/trace"
    26  	"google.golang.org/grpc"
    27  )
    28  
    29  // EnableRPCServerTracing turns on Stackdriver tracing. The returned
    30  // options must be passed to the GRPC server. The supplied
    31  // projectID can be nil for GCP but might need to be set for other
    32  // cloud platforms. Refer to the appropriate documentation. The percentage
    33  // of traced requests can be set between 0 and 100. Note that 0 does not
    34  // disable tracing entirely but causes the default configuration to be used.
    35  func EnableRPCServerTracing(projectID string, percent int) ([]grpc.ServerOption, error) {
    36  	if err := exporter(projectID); err != nil {
    37  		return nil, err
    38  	}
    39  	if err := applyConfig(percent); err != nil {
    40  		return nil, err
    41  	}
    42  	// Register the views to collect server request count.
    43  	if err := view.Register(ocgrpc.DefaultServerViews...); err != nil {
    44  		return nil, err
    45  	}
    46  
    47  	return []grpc.ServerOption{grpc.StatsHandler(&ocgrpc.ServerHandler{})}, nil
    48  }
    49  
    50  // EnableHTTPServerTracing turns on Stackdriver tracing for HTTP requests
    51  // on the default ServeMux. The returned handler must be passed to the HTTP
    52  // server. The supplied projectID can be nil for GCP but might need to be set
    53  // for other cloud platforms. Refer to the appropriate documentation.
    54  // The percentage of traced requests can be set between 0 and 100. Note that 0
    55  // does not disable tracing entirely but causes the default configuration to be
    56  // used.
    57  func EnableHTTPServerTracing(projectID string, percent int) (http.Handler, error) {
    58  	if err := exporter(projectID); err != nil {
    59  		return nil, err
    60  	}
    61  	if err := applyConfig(percent); err != nil {
    62  		return nil, err
    63  	}
    64  	if err := view.Register(ochttp.DefaultServerViews...); err != nil {
    65  		return nil, err
    66  	}
    67  	return &ochttp.Handler{}, nil
    68  }
    69  
    70  func exporter(projectID string) error {
    71  	sde, err := stackdriver.NewExporter(stackdriver.Options{ProjectID: projectID})
    72  	if err != nil {
    73  		return err
    74  	}
    75  	view.RegisterExporter(sde)
    76  	trace.RegisterExporter(sde)
    77  
    78  	return nil
    79  }
    80  
    81  func applyConfig(percent int) error {
    82  	switch {
    83  	case percent == 0:
    84  		// Use the default config, which traces relatively few requests.
    85  	case percent == 100:
    86  		trace.ApplyConfig(trace.Config{DefaultSampler: trace.AlwaysSample()})
    87  	case percent > 100:
    88  		return errors.New("cannot trace more than 100 percent of requests")
    89  	default:
    90  		trace.ApplyConfig(trace.Config{DefaultSampler: trace.ProbabilitySampler(float64(percent) / 100.0)})
    91  	}
    92  	return nil
    93  }