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122 lines
3.3 KiB
Go
122 lines
3.3 KiB
Go
package monitoring
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import (
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"encoding/json"
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"fmt"
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"net/http"
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"strconv"
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"strings"
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"github.com/newrelic/go-agent/v3/newrelic"
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"github.com/pkg/errors"
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"github.com/smallstep/certificates/logging"
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)
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// Middleware is a function returns another http.Handler that wraps the given
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// handler.
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type Middleware func(next http.Handler) http.Handler
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// Monitoring is the type holding a middleware that traces the request to an
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// application.
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type Monitoring struct {
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middleware Middleware
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}
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// monitoring config represents the JSON attributes used for configuration. At
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// this moment only fields for NewRelic are supported.
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type monitoringConfig struct {
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Type string `json:"type,omitempty"`
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Name string `json:"name"`
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Key string `json:"key"`
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}
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// New initializes the monitoring with the given configuration.
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// Right now it only supports newrelic as the monitoring backend.
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func New(raw json.RawMessage) (*Monitoring, error) {
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var config monitoringConfig
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if err := json.Unmarshal(raw, &config); err != nil {
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return nil, errors.Wrap(err, "error unmarshalling monitoring attribute")
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}
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m := new(Monitoring)
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switch strings.ToLower(config.Type) {
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case "", "newrelic":
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app, err := newrelic.NewApplication(
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newrelic.ConfigAppName(config.Name),
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newrelic.ConfigLicense(config.Key),
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)
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if err != nil {
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return nil, errors.Wrap(err, "error loading New Relic application")
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}
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m.middleware = newRelicMiddleware(app)
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default:
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return nil, errors.Errorf("unsupported monitoring.type '%s'", config.Type)
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}
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return m, nil
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}
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// Middleware is an HTTP middleware that traces the request with the configured
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// monitoring backednd.
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func (m *Monitoring) Middleware(next http.Handler) http.Handler {
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return m.middleware(next)
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}
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func newRelicMiddleware(app *newrelic.Application) Middleware {
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return func(next http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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// Start transaction
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txn := app.StartTransaction(transactionName(r))
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defer txn.End()
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w = txn.SetWebResponse(w)
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txn.SetWebRequestHTTP(r)
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// Wrap request writer if necessary
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rw := logging.NewResponseLogger(w)
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// Call next handler
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next.ServeHTTP(rw, r)
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// Report status (using same key NewRelic uses by default)
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status := rw.StatusCode()
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txn.AddAttribute("httpResponseCode", strconv.Itoa(status))
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// Add custom attributes
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if v, ok := logging.GetRequestID(r.Context()); ok {
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txn.AddAttribute("request.id", v)
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}
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// Report errors if necessary
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if status >= http.StatusBadRequest {
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var errorNoticed bool
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if fields := rw.Fields(); fields != nil {
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if v, ok := fields["error"]; ok {
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if err, ok := v.(error); ok {
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txn.NoticeError(err)
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errorNoticed = true
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}
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}
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}
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if !errorNoticed {
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txn.NoticeError(fmt.Errorf("request failed with status code %d", status))
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}
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}
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})
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}
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}
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func transactionName(r *http.Request) string {
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// From https://github.com/gorilla/handlers
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uri := r.RequestURI
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// Requests using the CONNECT method over HTTP/2.0 must use
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// the authority field (aka r.Host) to identify the target.
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// Refer: https://httpwg.github.io/specs/rfc7540.html#CONNECT
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if r.ProtoMajor == 2 && r.Method == "CONNECT" {
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uri = r.Host
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}
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if uri == "" {
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uri = r.URL.RequestURI()
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}
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return uri
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}
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