Integrate on Google Cloud Functions GoLang

1go get go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp

1package instrumentation
2
3import (
4    "net/http"
5
6    "go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
7    semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
8    "go.opentelemetry.io/otel/trace"
9
10    "cloud.google.com/go/compute/metadata"
11
12    dtTrace "github.com/dynatrace-oss/opentelemetry-exporter-go/core/trace"
13)
14
15type HttpHandler = func(w http.ResponseWriter, r *http.Request)
16
17func InstrumentHandler(
18    functionName string,
19    function HttpHandler,
20    tracerProvider *dtTrace.DtTracerProvider) HttpHandler {
21
22    // get project id and region from Google Compute Engine metadata
23    projectId, err := getProjectId()
24    if err != nil {
25        // handle error
26    }
27    region, err := getRegion()
28    if err != nil {
29        // handle error
30    }
31
32    // set at least these required attributes
33    opts := []trace.SpanStartOption{
34        trace.WithAttributes(
35            semconv.FaaSTriggerHTTP,
36            semconv.CloudProviderGCP,
37            semconv.CloudPlatformGCPCloudFunctions,
38            semconv.FaaSIDKey.String(createFaasId(projectId, region, functionName)),
39            semconv.FaaSNameKey.String(functionName),
40            semconv.CloudRegionKey.String(region),
41        ),
42    }
43
44    // create instrumented handler
45    handler := otelhttp.NewHandler(
46        http.HandlerFunc(function), functionName, otelhttp.WithSpanOptions(opts...),
47    )
48
49    return func(w http.ResponseWriter, r *http.Request) {
50        // call your function handler
51        handler.ServeHTTP(w, r)
52
53        // flush spans
54        tracerProvider.ForceFlush(r.Context())
55    }
56}
57
58func getProjectId() (string, error) {
59    return metadata.ProjectID()
60}
61
62func getRegion() (string, error) {
63    // Returned string has the format "projects/<numeric-project-id>/regions/<region>"
64    fullRegion, err := metadata.Get("instance/region")
65    if err != nil {
66        return "", err
67    }
68    fullRegionSplit := strings.Split(fullRegion, "/")
69    region := fullRegionSplit[len(fullRegionSplit)-1]
70    return region, nil
71}
72
73func createFaasId(projectId, region, functionName string) string {
74    return fmt.Sprintf("//cloudfunctions.googleapis.com/projects/%s/locations/%s/functions/%s",
75        projectId, region, functionName)
76}

1package myfunction
2
3import (
4    "net/http"
5
6    "instrumentation"
7    "otelsetup"
8
9    "github.com/GoogleCloudPlatform/functions-framework-go/functions"
10)
11
12func init() {
13    // see https://cloud.google.com/functions/docs/configuring/env-var#runtime_environment_variables_set_automatically
14    functionName, ok := os.LookupEnv("K_SERVICE")
15    if !ok {
16        // function name not found; assign a default or treat as an error
17    }
18    if tracerProvider, err := otelsetup.InitializeTracing(functionName); err == nil {
19        instrumentedHandler := instrumentation.InstrumentHandler(functionName, handler, tracerProvider)
20        functions.HTTP(functionName, instrumentedHandler)
21    } else {
22        // handle error, or register function anyway without instrumentation
23    }
24}
25
26func handler(w http.ResponseWriter, r *http.Request) {
27    // your code goes here
28}