89 lines
2.0 KiB
Go
89 lines
2.0 KiB
Go
package monitors
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import (
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"context"
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"fmt"
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"log"
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"net/http"
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"time"
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aireoneHttp "aireone.xyz/labtime/internal/http"
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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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var ErrInvalidStatusCode = errors.New("expected status code 200")
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type HTTPMonitor struct {
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Label string
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URL string
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Logger *log.Logger
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ResponseTimeMonitor *prometheus.GaugeVec
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}
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func (h *HTTPMonitor) ID() string {
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return h.Label
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}
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func (h *HTTPMonitor) Run() error {
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d, err := h.httpHealthCheck()
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if err != nil {
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return errors.Wrap(err, "error running http health check")
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}
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h.pushToPrometheus(d)
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return nil
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}
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func newHTTPDurationMiddleware(duration *time.Duration, proxied http.RoundTripper) *aireoneHttp.RoundTripperMiddleware {
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var t time.Time
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return &aireoneHttp.RoundTripperMiddleware{
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Proxied: proxied,
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OnBefore: func(_ *http.Request) {
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t = time.Now()
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},
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OnAfter: func(_ *http.Response) {
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*duration = time.Since(t)
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},
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}
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}
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type HTTPHealthCheckerData struct {
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Duration time.Duration
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}
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func (h *HTTPMonitor) httpHealthCheck() (*HTTPHealthCheckerData, error) {
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r, err := http.NewRequest(http.MethodHead, h.URL, http.NoBody)
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if err != nil {
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return nil, errors.Wrap(err, "error creating http request")
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}
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req := r.WithContext(context.TODO())
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var duration time.Duration
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client := &http.Client{
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Transport: aireoneHttp.NewLoggerMiddleware(h.Logger, newHTTPDurationMiddleware(&duration, http.DefaultTransport)),
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}
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resp, err := client.Do(req)
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if err != nil {
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return nil, err
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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return nil, errors.Wrap(ErrInvalidStatusCode, fmt.Sprintf("got status code %d", resp.StatusCode))
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}
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return &HTTPHealthCheckerData{
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Duration: duration,
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}, nil
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}
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func (h *HTTPMonitor) pushToPrometheus(d *HTTPHealthCheckerData) {
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h.Logger.Printf("Push metrics to Prometheus: Response time for %s: %v", h.Label, d.Duration.Seconds())
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h.ResponseTimeMonitor.With(prometheus.Labels{"target_name": h.Label}).Set(d.Duration.Seconds())
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}
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