85 lines
2.8 KiB
Go
85 lines
2.8 KiB
Go
// Copyright 2022 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package promhttp
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import (
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"context"
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"github.com/prometheus/client_golang/prometheus"
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)
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// Option are used to configure both handler (middleware) or round tripper.
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type Option interface {
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apply(*options)
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}
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// LabelValueFromCtx are used to compute the label value from request context.
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// Context can be filled with values from request through middleware.
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type LabelValueFromCtx func(ctx context.Context) string
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// options store options for both a handler or round tripper.
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type options struct {
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extraMethods []string
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getExemplarFn func(requestCtx context.Context) prometheus.Labels
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extraLabelsFromCtx map[string]LabelValueFromCtx
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}
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func defaultOptions() *options {
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return &options{
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getExemplarFn: func(ctx context.Context) prometheus.Labels { return nil },
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extraLabelsFromCtx: map[string]LabelValueFromCtx{},
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}
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}
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func (o *options) emptyDynamicLabels() prometheus.Labels {
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labels := prometheus.Labels{}
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for label := range o.extraLabelsFromCtx {
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labels[label] = ""
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}
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return labels
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}
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type optionApplyFunc func(*options)
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func (o optionApplyFunc) apply(opt *options) { o(opt) }
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// WithExtraMethods adds additional HTTP methods to the list of allowed methods.
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// See https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods for the default list.
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//
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// See the example for ExampleInstrumentHandlerWithExtraMethods for example usage.
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func WithExtraMethods(methods ...string) Option {
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return optionApplyFunc(func(o *options) {
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o.extraMethods = methods
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})
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}
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// WithExemplarFromContext adds allows to put a hook to all counter and histogram metrics.
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// If the hook function returns non-nil labels, exemplars will be added for that request, otherwise metric
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// will get instrumented without exemplar.
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func WithExemplarFromContext(getExemplarFn func(requestCtx context.Context) prometheus.Labels) Option {
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return optionApplyFunc(func(o *options) {
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o.getExemplarFn = getExemplarFn
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})
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}
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// WithLabelFromCtx registers a label for dynamic resolution with access to context.
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// See the example for ExampleInstrumentHandlerWithLabelResolver for example usage
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func WithLabelFromCtx(name string, valueFn LabelValueFromCtx) Option {
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return optionApplyFunc(func(o *options) {
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o.extraLabelsFromCtx[name] = valueFn
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})
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}
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