102 lines
2.7 KiB
Go
102 lines
2.7 KiB
Go
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package metrics
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import (
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"fmt"
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"net/http"
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"time"
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"github.com/pkg/errors"
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"github.com/prometheus/client_golang/prometheus"
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)
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// Metrics provides a simple way to track latency and http status
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type Metrics struct {
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latency *prometheus.SummaryVec
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status *prometheus.CounterVec
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}
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func New(prefix string) (*Metrics, error) {
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m := &Metrics{
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latency: prometheus.NewSummaryVec(prometheus.SummaryOpts{
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Namespace: prefix,
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Subsystem: "http",
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Name: "request_latency_ms",
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Help: "Latency in ms of http requests grouped by req path",
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}, []string{"path"}),
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status: prometheus.NewCounterVec(prometheus.CounterOpts{
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Namespace: prefix,
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Subsystem: "http",
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Name: "status_count",
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Help: "The count of http responses issued classified by status and api endpoint",
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}, []string{"path", "code"}),
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}
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if err := m.registerPromMetrics(); err != nil {
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return nil, errors.Wrap(err, "registration")
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}
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return m, nil
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}
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// registerPromMetrics registers all the metrics that eventmanger uses.
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func (m *Metrics) registerPromMetrics() error {
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if err := prometheus.Register(m.latency); err != nil {
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return errors.Wrap(err, "http request latency")
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}
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if err := prometheus.Register(m.status); err != nil {
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return errors.Wrap(err, "http response counter")
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}
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return nil
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}
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// Wrap calls a http.Handler and tracks status code and latency.
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func (m *Metrics) Wrap(prefix string, h http.Handler) http.HandlerFunc {
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return m.WrapFunc(prefix, h.ServeHTTP)
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}
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// WrapFunc calls a http.Handler and tracks status code and latency.
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func (m *Metrics) WrapFunc(prefix string, h http.HandlerFunc) http.HandlerFunc {
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return func(w http.ResponseWriter, req *http.Request) {
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start := time.Now()
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defer func() {
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m.HTTPLatency(prefix, start)
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}()
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lw := NewStatusRecorder(w)
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h(lw, req)
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m.HTTPStatus(prefix, lw.Status())
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}
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}
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// HTTPLatency records a request latency for a given url path.
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func (m *Metrics) HTTPLatency(path string, start time.Time) {
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m.latency.WithLabelValues(path).Observe(msSince(start))
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}
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// HTTPStatus records counts of http statuses, bucketed according to status types.
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func (m *Metrics) HTTPStatus(path string, status int) {
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m.status.WithLabelValues(path, fmt.Sprintf("%d", bucketHTTPStatus(status))).Inc()
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}
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// bucketHTTPStatus rounds down to the nearest hundred to facilitate categorizing http statuses.
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func bucketHTTPStatus(i int) int {
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return i - i%100
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}
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// msSince returns milliseconds since start.
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func msSince(start time.Time) float64 {
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return float64(time.Since(start)) / float64(time.Millisecond)
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}
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// buckets returns the default prometheus buckets scaled to milliseconds.
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func buckets() []float64 {
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r := []float64{}
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for _, v := range prometheus.DefBuckets {
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r = append(r, v*float64(time.Second/time.Millisecond))
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}
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return r
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}
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