From eb891d46831252c5329218bfbb606727685fea72 Mon Sep 17 00:00:00 2001 From: Dave Henderson Date: Sat, 22 Jan 2022 19:08:57 -0500 Subject: metrics: Enforce smaller set of method labels Signed-off-by: Dave Henderson --- metrics.go | 27 +++++++++++++++++++++++++-- modules/caddyhttp/metrics.go | 27 +++++++++++++++++++++++++-- modules/caddyhttp/metrics_test.go | 23 +++++++++++++++++++++++ 3 files changed, 73 insertions(+), 4 deletions(-) diff --git a/metrics.go b/metrics.go index ab9d797..9a56f73 100644 --- a/metrics.go +++ b/metrics.go @@ -3,7 +3,6 @@ package caddy import ( "net/http" "strconv" - "strings" "github.com/prometheus/client_golang/prometheus" "github.com/prometheus/client_golang/prometheus/collectors" @@ -47,7 +46,7 @@ func instrumentHandlerCounter(counter *prometheus.CounterVec, next http.Handler) next.ServeHTTP(d, r) counter.With(prometheus.Labels{ "code": sanitizeCode(d.status), - "method": strings.ToUpper(r.Method), + "method": sanitizeMethod(r.Method), }).Inc() }) } @@ -76,3 +75,27 @@ func sanitizeCode(s int) string { return strconv.Itoa(s) } } + +// Only support the list of "regular" HTTP methods, see +// https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods +var methodMap = map[string]string{ + "GET": http.MethodGet, "get": http.MethodGet, + "HEAD": http.MethodHead, "head": http.MethodHead, + "PUT": http.MethodPut, "put": http.MethodPut, + "POST": http.MethodPost, "post": http.MethodPost, + "DELETE": http.MethodDelete, "delete": http.MethodDelete, + "CONNECT": http.MethodConnect, "connect": http.MethodConnect, + "OPTIONS": http.MethodOptions, "options": http.MethodOptions, + "TRACE": http.MethodTrace, "trace": http.MethodTrace, + "PATCH": http.MethodPatch, "patch": http.MethodPatch, +} + +// sanitizeMethod sanitizes the method for use as a metric label. This helps +// prevent high cardinality on the method label. The name is always upper case. +func sanitizeMethod(m string) string { + if m, ok := methodMap[m]; ok { + return m + } + + return "other" +} diff --git a/modules/caddyhttp/metrics.go b/modules/caddyhttp/metrics.go index 3e5d639..8aa9184 100644 --- a/modules/caddyhttp/metrics.go +++ b/modules/caddyhttp/metrics.go @@ -4,7 +4,6 @@ import ( "context" "net/http" "strconv" - "strings" "sync" "time" @@ -109,7 +108,7 @@ func newMetricsInstrumentedHandler(handler string, mh MiddlewareHandler) *metric func (h *metricsInstrumentedHandler) ServeHTTP(w http.ResponseWriter, r *http.Request, next Handler) error { server := serverNameFromContext(r.Context()) labels := prometheus.Labels{"server": server, "handler": h.handler} - method := strings.ToUpper(r.Method) + method := sanitizeMethod(r.Method) // the "code" value is set later, but initialized here to eliminate the possibility // of a panic statusLabels := prometheus.Labels{"server": server, "handler": h.handler, "method": method, "code": ""} @@ -160,6 +159,30 @@ func sanitizeCode(code int) string { return strconv.Itoa(code) } +// Only support the list of "regular" HTTP methods, see +// https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods +var methodMap = map[string]string{ + "GET": http.MethodGet, "get": http.MethodGet, + "HEAD": http.MethodHead, "head": http.MethodHead, + "PUT": http.MethodPut, "put": http.MethodPut, + "POST": http.MethodPost, "post": http.MethodPost, + "DELETE": http.MethodDelete, "delete": http.MethodDelete, + "CONNECT": http.MethodConnect, "connect": http.MethodConnect, + "OPTIONS": http.MethodOptions, "options": http.MethodOptions, + "TRACE": http.MethodTrace, "trace": http.MethodTrace, + "PATCH": http.MethodPatch, "patch": http.MethodPatch, +} + +// sanitizeMethod sanitizes the method for use as a metric label. This helps +// prevent high cardinality on the method label. The name is always upper case. +func sanitizeMethod(m string) string { + if m, ok := methodMap[m]; ok { + return m + } + + return "other" +} + // taken from https://github.com/prometheus/client_golang/blob/6007b2b5cae01203111de55f753e76d8dac1f529/prometheus/promhttp/instrument_server.go#L298 func computeApproximateRequestSize(r *http.Request) int { s := 0 diff --git a/modules/caddyhttp/metrics_test.go b/modules/caddyhttp/metrics_test.go index 6311935..78e380b 100644 --- a/modules/caddyhttp/metrics_test.go +++ b/modules/caddyhttp/metrics_test.go @@ -5,6 +5,7 @@ import ( "errors" "net/http" "net/http/httptest" + "strings" "testing" "github.com/prometheus/client_golang/prometheus/testutil" @@ -82,3 +83,25 @@ type middlewareHandlerFunc func(http.ResponseWriter, *http.Request, Handler) err func (f middlewareHandlerFunc) ServeHTTP(w http.ResponseWriter, r *http.Request, h Handler) error { return f(w, r, h) } + +func TestSanitizeMethod(t *testing.T) { + tests := []struct { + method string + expected string + }{ + {method: "get", expected: "GET"}, + {method: "POST", expected: "POST"}, + {method: "OPTIONS", expected: "OPTIONS"}, + {method: "connect", expected: "CONNECT"}, + {method: "trace", expected: "TRACE"}, + {method: "UNKNOWN", expected: "other"}, + {method: strings.Repeat("ohno", 9999), expected: "other"}, + } + + for _, d := range tests { + actual := sanitizeMethod(d.method) + if actual != d.expected { + t.Errorf("Not same: expected %#v, but got %#v", d.expected, actual) + } + } +} -- cgit v1.2.3