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metrics: Record request metrics on HTTP errors #5979

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Dec 15, 2023
Merged

metrics: Record request metrics on HTTP errors #5979

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655ad1b
Record request metrics on HTTP errors
tgeoghegan Dec 13, 2023
e860711
Review feedback
tgeoghegan Dec 14, 2023
fbdd348
Collapse metrics tests together since gatherer is global
tgeoghegan Dec 15, 2023
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34 changes: 23 additions & 11 deletions modules/caddyhttp/metrics.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ package caddyhttp

import (
"context"
"errors"
"net/http"
"sync"
"time"
Expand Down Expand Up @@ -137,22 +138,33 @@ func (h *metricsInstrumentedHandler) ServeHTTP(w http.ResponseWriter, r *http.Re
err := h.mh.ServeHTTP(wrec, r, next)
dur := time.Since(start).Seconds()
httpMetrics.requestCount.With(labels).Inc()

observeRequest := func(status int) {
// If the code hasn't been set yet, and we didn't encounter an error, we're
// probably falling through with an empty handler.
if statusLabels["code"] == "" {
// we still sanitize it, even though it's likely to be 0. A 200 is
// returned on fallthrough so we want to reflect that.
statusLabels["code"] = metrics.SanitizeCode(status)
}

httpMetrics.requestDuration.With(statusLabels).Observe(dur)
httpMetrics.requestSize.With(statusLabels).Observe(float64(computeApproximateRequestSize(r)))
httpMetrics.responseSize.With(statusLabels).Observe(float64(wrec.Size()))
}

if err != nil {
var handlerErr HandlerError
if errors.As(err, &handlerErr) {
observeRequest(handlerErr.StatusCode)
}

httpMetrics.requestErrors.With(labels).Inc()
return err
}

// If the code hasn't been set yet, and we didn't encounter an error, we're
// probably falling through with an empty handler.
if statusLabels["code"] == "" {
// we still sanitize it, even though it's likely to be 0. A 200 is
// returned on fallthrough so we want to reflect that.
statusLabels["code"] = metrics.SanitizeCode(wrec.Status())
return err
}

httpMetrics.requestDuration.With(statusLabels).Observe(dur)
httpMetrics.requestSize.With(statusLabels).Observe(float64(computeApproximateRequestSize(r)))
httpMetrics.responseSize.With(statusLabels).Observe(float64(wrec.Size()))
observeRequest(wrec.Status())

return nil
}
Expand Down
119 changes: 119 additions & 0 deletions modules/caddyhttp/metrics_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -5,8 +5,10 @@ import (
"errors"
"net/http"
"net/http/httptest"
"strings"
"testing"

"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/testutil"
)

Expand Down Expand Up @@ -75,6 +77,123 @@ func TestMetricsInstrumentedHandler(t *testing.T) {
if actual := w.Result().Header; len(actual) != 0 {
t.Errorf("Not empty: expected headers to be empty, but got %#v", actual)
}

// handler returning an error with an HTTP status
mh = middlewareHandlerFunc(func(w http.ResponseWriter, r *http.Request, h Handler) error {
return Error(http.StatusTooManyRequests, nil)
})

ih = newMetricsInstrumentedHandler("foo", mh)

r = httptest.NewRequest("GET", "/", nil)
w = httptest.NewRecorder()

if err := ih.ServeHTTP(w, r, nil); err == nil {
t.Errorf("expected error to be propagated")
}

expected := `
# HELP caddy_http_request_duration_seconds Histogram of round-trip request durations.
# TYPE caddy_http_request_duration_seconds histogram
caddy_http_request_duration_seconds_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="0.005"} 1
caddy_http_request_duration_seconds_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="0.01"} 1
caddy_http_request_duration_seconds_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="0.025"} 1
caddy_http_request_duration_seconds_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="0.05"} 1
caddy_http_request_duration_seconds_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="0.1"} 1
caddy_http_request_duration_seconds_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="0.25"} 1
caddy_http_request_duration_seconds_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="0.5"} 1
caddy_http_request_duration_seconds_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="1"} 1
caddy_http_request_duration_seconds_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="2.5"} 1
caddy_http_request_duration_seconds_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="5"} 1
caddy_http_request_duration_seconds_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="10"} 1
caddy_http_request_duration_seconds_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="+Inf"} 1
caddy_http_request_duration_seconds_count{code="429",handler="foo",method="GET",server="UNKNOWN"} 1
# HELP caddy_http_request_size_bytes Total size of the request. Includes body
# TYPE caddy_http_request_size_bytes histogram
caddy_http_request_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="256"} 1
caddy_http_request_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="1024"} 1
caddy_http_request_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="4096"} 1
caddy_http_request_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="16384"} 1
caddy_http_request_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="65536"} 1
caddy_http_request_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="262144"} 1
caddy_http_request_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="1.048576e+06"} 1
caddy_http_request_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="4.194304e+06"} 1
caddy_http_request_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="+Inf"} 1
caddy_http_request_size_bytes_sum{code="200",handler="bar",method="GET",server="UNKNOWN"} 23
caddy_http_request_size_bytes_count{code="200",handler="bar",method="GET",server="UNKNOWN"} 1
caddy_http_request_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="256"} 1
caddy_http_request_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="1024"} 1
caddy_http_request_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="4096"} 1
caddy_http_request_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="16384"} 1
caddy_http_request_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="65536"} 1
caddy_http_request_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="262144"} 1
caddy_http_request_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="1.048576e+06"} 1
caddy_http_request_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="4.194304e+06"} 1
caddy_http_request_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="+Inf"} 1
caddy_http_request_size_bytes_sum{code="200",handler="empty",method="GET",server="UNKNOWN"} 23
caddy_http_request_size_bytes_count{code="200",handler="empty",method="GET",server="UNKNOWN"} 1
caddy_http_request_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="256"} 1
caddy_http_request_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="1024"} 1
caddy_http_request_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="4096"} 1
caddy_http_request_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="16384"} 1
caddy_http_request_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="65536"} 1
caddy_http_request_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="262144"} 1
caddy_http_request_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="1.048576e+06"} 1
caddy_http_request_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="4.194304e+06"} 1
caddy_http_request_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="+Inf"} 1
caddy_http_request_size_bytes_sum{code="429",handler="foo",method="GET",server="UNKNOWN"} 23
caddy_http_request_size_bytes_count{code="429",handler="foo",method="GET",server="UNKNOWN"} 1
# HELP caddy_http_response_size_bytes Size of the returned response.
# TYPE caddy_http_response_size_bytes histogram
caddy_http_response_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="256"} 1
caddy_http_response_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="1024"} 1
caddy_http_response_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="4096"} 1
caddy_http_response_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="16384"} 1
caddy_http_response_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="65536"} 1
caddy_http_response_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="262144"} 1
caddy_http_response_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="1.048576e+06"} 1
caddy_http_response_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="4.194304e+06"} 1
caddy_http_response_size_bytes_bucket{code="200",handler="bar",method="GET",server="UNKNOWN",le="+Inf"} 1
caddy_http_response_size_bytes_sum{code="200",handler="bar",method="GET",server="UNKNOWN"} 12
caddy_http_response_size_bytes_count{code="200",handler="bar",method="GET",server="UNKNOWN"} 1
caddy_http_response_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="256"} 1
caddy_http_response_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="1024"} 1
caddy_http_response_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="4096"} 1
caddy_http_response_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="16384"} 1
caddy_http_response_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="65536"} 1
caddy_http_response_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="262144"} 1
caddy_http_response_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="1.048576e+06"} 1
caddy_http_response_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="4.194304e+06"} 1
caddy_http_response_size_bytes_bucket{code="200",handler="empty",method="GET",server="UNKNOWN",le="+Inf"} 1
caddy_http_response_size_bytes_sum{code="200",handler="empty",method="GET",server="UNKNOWN"} 0
caddy_http_response_size_bytes_count{code="200",handler="empty",method="GET",server="UNKNOWN"} 1
caddy_http_response_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="256"} 1
caddy_http_response_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="1024"} 1
caddy_http_response_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="4096"} 1
caddy_http_response_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="16384"} 1
caddy_http_response_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="65536"} 1
caddy_http_response_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="262144"} 1
caddy_http_response_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="1.048576e+06"} 1
caddy_http_response_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="4.194304e+06"} 1
caddy_http_response_size_bytes_bucket{code="429",handler="foo",method="GET",server="UNKNOWN",le="+Inf"} 1
caddy_http_response_size_bytes_sum{code="429",handler="foo",method="GET",server="UNKNOWN"} 0
caddy_http_response_size_bytes_count{code="429",handler="foo",method="GET",server="UNKNOWN"} 1
# HELP caddy_http_request_errors_total Number of requests resulting in middleware errors.
# TYPE caddy_http_request_errors_total counter
caddy_http_request_errors_total{handler="bar",server="UNKNOWN"} 1
caddy_http_request_errors_total{handler="foo",server="UNKNOWN"} 1
`
if err := testutil.GatherAndCompare(prometheus.DefaultGatherer, strings.NewReader(expected),
"caddy_http_request_size_bytes",
"caddy_http_response_size_bytes",
// caddy_http_request_duration_seconds_sum will vary based on how long the test took to run,
// so we check just the _bucket and _count metrics
"caddy_http_request_duration_seconds_bucket",
"caddy_http_request_duration_seconds_count",
"caddy_http_request_errors_total",
); err != nil {
t.Errorf("received unexpected error: %s", err)
}
}

type middlewareHandlerFunc func(http.ResponseWriter, *http.Request, Handler) error
Expand Down
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