Take into account curried labels in promhttp
This commit is contained in:
parent
1ba60c7d58
commit
9ac0bad606
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@ -45,12 +45,11 @@ func InstrumentRoundTripperInFlight(gauge prometheus.Gauge, next http.RoundTripp
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// InstrumentRoundTripperCounter is a middleware that wraps the provided
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// http.RoundTripper to observe the request result with the provided CounterVec.
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// The CounterVec must have zero, one, or two labels. The only allowed label
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// names are "code" and "method". The function panics if any other instance
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// labels are provided. Partitioning of the CounterVec happens by HTTP status
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// code and/or HTTP method if the respective instance label names are present
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// in the CounterVec. For unpartitioned counting, use a CounterVec with
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// zero labels.
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// The CounterVec must have zero, one, or two non-const non-curried labels. For
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// those, the only allowed label names are "code" and "method". The function
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// panics otherwise. Partitioning of the CounterVec happens by HTTP status code
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// and/or HTTP method if the respective instance label names are present in the
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// CounterVec. For unpartitioned counting, use a CounterVec with zero labels.
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//
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// If the wrapped RoundTripper panics or returns a non-nil error, the Counter
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// is not incremented.
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@ -14,6 +14,7 @@
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package promhttp
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import (
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"errors"
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"net/http"
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"strconv"
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"strings"
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@ -42,10 +43,10 @@ func InstrumentHandlerInFlight(g prometheus.Gauge, next http.Handler) http.Handl
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// InstrumentHandlerDuration is a middleware that wraps the provided
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// http.Handler to observe the request duration with the provided ObserverVec.
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// The ObserverVec must have zero, one, or two labels. The only allowed label
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// names are "code" and "method". The function panics if any other instance
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// labels are provided. The Observe method of the Observer in the ObserverVec
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// is called with the request duration in seconds. Partitioning happens by HTTP
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// The ObserverVec must have zero, one, or two non-const non-curried labels. For
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// those, the only allowed label names are "code" and "method". The function
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// panics otherwise. The Observe method of the Observer in the ObserverVec is
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// called with the request duration in seconds. Partitioning happens by HTTP
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// status code and/or HTTP method if the respective instance label names are
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// present in the ObserverVec. For unpartitioned observations, use an
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// ObserverVec with zero labels. Note that partitioning of Histograms is
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@ -77,14 +78,13 @@ func InstrumentHandlerDuration(obs prometheus.ObserverVec, next http.Handler) ht
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})
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}
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// InstrumentHandlerCounter is a middleware that wraps the provided
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// http.Handler to observe the request result with the provided CounterVec.
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// The CounterVec must have zero, one, or two labels. The only allowed label
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// names are "code" and "method". The function panics if any other instance
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// labels are provided. Partitioning of the CounterVec happens by HTTP status
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// code and/or HTTP method if the respective instance label names are present
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// in the CounterVec. For unpartitioned counting, use a CounterVec with
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// zero labels.
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// InstrumentHandlerCounter is a middleware that wraps the provided http.Handler
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// to observe the request result with the provided CounterVec. The CounterVec
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// must have zero, one, or two non-const non-curried labels. For those, the only
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// allowed label names are "code" and "method". The function panics
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// otherwise. Partitioning of the CounterVec happens by HTTP status code and/or
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// HTTP method if the respective instance label names are present in the
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// CounterVec. For unpartitioned counting, use a CounterVec with zero labels.
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//
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// If the wrapped Handler does not set a status code, a status code of 200 is assumed.
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//
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@ -111,14 +111,13 @@ func InstrumentHandlerCounter(counter *prometheus.CounterVec, next http.Handler)
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// InstrumentHandlerTimeToWriteHeader is a middleware that wraps the provided
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// http.Handler to observe with the provided ObserverVec the request duration
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// until the response headers are written. The ObserverVec must have zero, one,
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// or two labels. The only allowed label names are "code" and "method". The
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// function panics if any other instance labels are provided. The Observe
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// method of the Observer in the ObserverVec is called with the request
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// duration in seconds. Partitioning happens by HTTP status code and/or HTTP
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// method if the respective instance label names are present in the
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// ObserverVec. For unpartitioned observations, use an ObserverVec with zero
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// labels. Note that partitioning of Histograms is expensive and should be used
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// judiciously.
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// or two non-const non-curried labels. For those, the only allowed label names
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// are "code" and "method". The function panics otherwise. The Observe method of
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// the Observer in the ObserverVec is called with the request duration in
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// seconds. Partitioning happens by HTTP status code and/or HTTP method if the
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// respective instance label names are present in the ObserverVec. For
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// unpartitioned observations, use an ObserverVec with zero labels. Note that
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// partitioning of Histograms is expensive and should be used judiciously.
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//
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// If the wrapped Handler panics before calling WriteHeader, no value is
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// reported.
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@ -140,15 +139,15 @@ func InstrumentHandlerTimeToWriteHeader(obs prometheus.ObserverVec, next http.Ha
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}
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// InstrumentHandlerRequestSize is a middleware that wraps the provided
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// http.Handler to observe the request size with the provided ObserverVec.
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// The ObserverVec must have zero, one, or two labels. The only allowed label
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// names are "code" and "method". The function panics if any other instance
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// labels are provided. The Observe method of the Observer in the ObserverVec
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// is called with the request size in bytes. Partitioning happens by HTTP
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// status code and/or HTTP method if the respective instance label names are
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// present in the ObserverVec. For unpartitioned observations, use an
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// ObserverVec with zero labels. Note that partitioning of Histograms is
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// expensive and should be used judiciously.
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// http.Handler to observe the request size with the provided ObserverVec. The
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// ObserverVec must have zero, one, or two non-const non-curried labels. For
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// those, the only allowed label names are "code" and "method". The function
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// panics otherwise. The Observe method of the Observer in the ObserverVec is
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// called with the request size in bytes. Partitioning happens by HTTP status
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// code and/or HTTP method if the respective instance label names are present in
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// the ObserverVec. For unpartitioned observations, use an ObserverVec with zero
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// labels. Note that partitioning of Histograms is expensive and should be used
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// judiciously.
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//
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// If the wrapped Handler does not set a status code, a status code of 200 is assumed.
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//
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@ -175,15 +174,15 @@ func InstrumentHandlerRequestSize(obs prometheus.ObserverVec, next http.Handler)
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}
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// InstrumentHandlerResponseSize is a middleware that wraps the provided
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// http.Handler to observe the response size with the provided ObserverVec.
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// The ObserverVec must have zero, one, or two labels. The only allowed label
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// names are "code" and "method". The function panics if any other instance
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// labels are provided. The Observe method of the Observer in the ObserverVec
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// is called with the response size in bytes. Partitioning happens by HTTP
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// status code and/or HTTP method if the respective instance label names are
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// present in the ObserverVec. For unpartitioned observations, use an
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// ObserverVec with zero labels. Note that partitioning of Histograms is
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// expensive and should be used judiciously.
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// http.Handler to observe the response size with the provided ObserverVec. The
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// ObserverVec must have zero, one, or two non-const non-curried labels. For
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// those, the only allowed label names are "code" and "method". The function
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// panics otherwise. The Observe method of the Observer in the ObserverVec is
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// called with the response size in bytes. Partitioning happens by HTTP status
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// code and/or HTTP method if the respective instance label names are present in
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// the ObserverVec. For unpartitioned observations, use an ObserverVec with zero
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// labels. Note that partitioning of Histograms is expensive and should be used
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// judiciously.
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//
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// If the wrapped Handler does not set a status code, a status code of 200 is assumed.
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//
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@ -204,9 +203,12 @@ func checkLabels(c prometheus.Collector) (code bool, method bool) {
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// once Descriptors can have their dimensionality queried.
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var (
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desc *prometheus.Desc
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m prometheus.Metric
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pm dto.Metric
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lvs []string
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)
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// Get the Desc from the Collector.
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descc := make(chan *prometheus.Desc, 1)
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c.Describe(descc)
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@ -223,49 +225,54 @@ func checkLabels(c prometheus.Collector) (code bool, method bool) {
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close(descc)
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if _, err := prometheus.NewConstMetric(desc, prometheus.UntypedValue, 0); err == nil {
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return
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// Create a ConstMetric with the Desc. Since we don't know how many
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// variable labels there are, try for as long as it needs.
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for err := errors.New("dummy"); err != nil; lvs = append(lvs, magicString) {
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m, err = prometheus.NewConstMetric(desc, prometheus.UntypedValue, 0, lvs...)
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}
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if m, err := prometheus.NewConstMetric(desc, prometheus.UntypedValue, 0, magicString); err == nil {
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if err := m.Write(&pm); err != nil {
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panic("error checking metric for labels")
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}
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for _, label := range pm.Label {
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name, value := label.GetName(), label.GetValue()
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if value != magicString {
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continue
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}
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switch name {
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case "code":
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code = true
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case "method":
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method = true
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default:
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panic("metric partitioned with non-supported labels")
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}
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return
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}
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panic("previously set label not found – this must never happen")
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// Write out the metric into a proto message and look at the labels.
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// If the value is not the magicString, it is a constLabel, which doesn't interest us.
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// If the label is curried, it doesn't interest us.
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// In all other cases, only "code" or "method" is allowed.
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if err := m.Write(&pm); err != nil {
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panic("error checking metric for labels")
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}
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if m, err := prometheus.NewConstMetric(desc, prometheus.UntypedValue, 0, magicString, magicString); err == nil {
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if err := m.Write(&pm); err != nil {
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panic("error checking metric for labels")
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for _, label := range pm.Label {
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name, value := label.GetName(), label.GetValue()
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if value != magicString || isLabelCurried(c, name) {
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continue
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}
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for _, label := range pm.Label {
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name, value := label.GetName(), label.GetValue()
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if value != magicString {
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continue
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}
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if name == "code" || name == "method" {
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continue
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}
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switch name {
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case "code":
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code = true
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case "method":
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method = true
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default:
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panic("metric partitioned with non-supported labels")
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}
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code = true
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method = true
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return
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}
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panic("metric partitioned with non-supported labels")
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return
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}
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func isLabelCurried(c prometheus.Collector, label string) bool {
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// This is even hackier than the label test above.
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// We essentially try to curry again and see if it works.
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// But for that, we need to type-convert to the two
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// types we use here, ObserverVec or *CounterVec.
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switch v := c.(type) {
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case *prometheus.CounterVec:
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if _, err := v.CurryWith(prometheus.Labels{label: "dummy"}); err == nil {
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return false
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}
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case prometheus.ObserverVec:
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if _, err := v.CurryWith(prometheus.Labels{label: "dummy"}); err == nil {
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return false
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}
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default:
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panic("unsupported metric vec type")
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}
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return true
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}
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// emptyLabels is a one-time allocation for non-partitioned metrics to avoid
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@ -23,6 +23,162 @@ import (
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"github.com/prometheus/client_golang/prometheus"
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)
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func TestLabelCheck(t *testing.T) {
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scenarios := map[string]struct {
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varLabels []string
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constLabels []string
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curriedLabels []string
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ok bool
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}{
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"empty": {
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varLabels: []string{},
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constLabels: []string{},
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curriedLabels: []string{},
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ok: true,
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},
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"code as single var label": {
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varLabels: []string{"code"},
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constLabels: []string{},
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curriedLabels: []string{},
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ok: true,
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},
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"method as single var label": {
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varLabels: []string{"method"},
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constLabels: []string{},
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curriedLabels: []string{},
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ok: true,
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},
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"cade and method as var labels": {
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varLabels: []string{"method", "code"},
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constLabels: []string{},
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curriedLabels: []string{},
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ok: true,
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},
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"valid case with all labels used": {
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varLabels: []string{"code", "method"},
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constLabels: []string{"foo", "bar"},
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curriedLabels: []string{"dings", "bums"},
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ok: true,
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},
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"unsupported var label": {
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varLabels: []string{"foo"},
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constLabels: []string{},
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curriedLabels: []string{},
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ok: false,
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},
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"mixed var labels": {
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varLabels: []string{"method", "foo", "code"},
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constLabels: []string{},
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curriedLabels: []string{},
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ok: false,
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},
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"unsupported var label but curried": {
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varLabels: []string{},
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constLabels: []string{},
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curriedLabels: []string{"foo"},
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ok: true,
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},
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"mixed var labels but unsupported curried": {
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varLabels: []string{"code", "method"},
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constLabels: []string{},
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curriedLabels: []string{"foo"},
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ok: true,
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},
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"supported label as const and curry": {
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varLabels: []string{},
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constLabels: []string{"code"},
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curriedLabels: []string{"method"},
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ok: true,
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},
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"supported label as const and curry with unsupported as var": {
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varLabels: []string{"foo"},
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constLabels: []string{"code"},
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curriedLabels: []string{"method"},
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ok: false,
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},
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}
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for name, sc := range scenarios {
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t.Run(name, func(t *testing.T) {
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constLabels := prometheus.Labels{}
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for _, l := range sc.constLabels {
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constLabels[l] = "dummy"
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}
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c := prometheus.NewCounterVec(
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prometheus.CounterOpts{
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Name: "c",
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Help: "c help",
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ConstLabels: constLabels,
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},
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append(sc.varLabels, sc.curriedLabels...),
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)
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o := prometheus.ObserverVec(prometheus.NewHistogramVec(
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prometheus.HistogramOpts{
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Name: "c",
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Help: "c help",
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ConstLabels: constLabels,
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},
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append(sc.varLabels, sc.curriedLabels...),
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))
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for _, l := range sc.curriedLabels {
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c = c.MustCurryWith(prometheus.Labels{l: "dummy"})
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o = o.MustCurryWith(prometheus.Labels{l: "dummy"})
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}
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func() {
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defer func() {
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if err := recover(); err != nil {
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if sc.ok {
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t.Error("unexpected panic:", err)
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}
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} else if !sc.ok {
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t.Error("expected panic")
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}
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}()
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InstrumentHandlerCounter(c, nil)
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}()
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func() {
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defer func() {
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if err := recover(); err != nil {
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if sc.ok {
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t.Error("unexpected panic:", err)
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}
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} else if !sc.ok {
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t.Error("expected panic")
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}
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}()
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InstrumentHandlerDuration(o, nil)
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}()
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if sc.ok {
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// Test if wantCode and wantMethod were detected correctly.
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var wantCode, wantMethod bool
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for _, l := range sc.varLabels {
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if l == "code" {
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wantCode = true
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}
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if l == "method" {
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wantMethod = true
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}
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}
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gotCode, gotMethod := checkLabels(c)
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if gotCode != wantCode {
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t.Errorf("wanted code=%t for counter, got code=%t", wantCode, gotCode)
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}
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if gotMethod != wantMethod {
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t.Errorf("wanted method=%t for counter, got method=%t", wantMethod, gotMethod)
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}
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gotCode, gotMethod = checkLabels(o)
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if gotCode != wantCode {
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t.Errorf("wanted code=%t for observer, got code=%t", wantCode, gotCode)
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}
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if gotMethod != wantMethod {
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t.Errorf("wanted method=%t for observer, got method=%t", wantMethod, gotMethod)
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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 TestMiddlewareAPI(t *testing.T) {
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reg := prometheus.NewRegistry()
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