khenaidoo | ab1f7bd | 2019-11-14 14:00:27 -0500 | [diff] [blame] | 1 | // Copyright 2018 The Prometheus Authors |
| 2 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 3 | // you may not use this file except in compliance with the License. |
| 4 | // You may obtain a copy of the License at |
| 5 | // |
| 6 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 7 | // |
| 8 | // Unless required by applicable law or agreed to in writing, software |
| 9 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 10 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 11 | // See the License for the specific language governing permissions and |
| 12 | // limitations under the License. |
| 13 | |
| 14 | package prometheus |
| 15 | |
| 16 | import ( |
| 17 | "fmt" |
| 18 | "sort" |
| 19 | |
khenaidoo | d948f77 | 2021-08-11 17:49:24 -0400 | [diff] [blame^] | 20 | //nolint:staticcheck // Ignore SA1019. Need to keep deprecated package for compatibility. |
khenaidoo | ab1f7bd | 2019-11-14 14:00:27 -0500 | [diff] [blame] | 21 | "github.com/golang/protobuf/proto" |
| 22 | |
| 23 | dto "github.com/prometheus/client_model/go" |
| 24 | ) |
| 25 | |
| 26 | // WrapRegistererWith returns a Registerer wrapping the provided |
| 27 | // Registerer. Collectors registered with the returned Registerer will be |
| 28 | // registered with the wrapped Registerer in a modified way. The modified |
| 29 | // Collector adds the provided Labels to all Metrics it collects (as |
| 30 | // ConstLabels). The Metrics collected by the unmodified Collector must not |
khenaidoo | d948f77 | 2021-08-11 17:49:24 -0400 | [diff] [blame^] | 31 | // duplicate any of those labels. Wrapping a nil value is valid, resulting |
| 32 | // in a no-op Registerer. |
khenaidoo | ab1f7bd | 2019-11-14 14:00:27 -0500 | [diff] [blame] | 33 | // |
| 34 | // WrapRegistererWith provides a way to add fixed labels to a subset of |
khenaidoo | d948f77 | 2021-08-11 17:49:24 -0400 | [diff] [blame^] | 35 | // Collectors. It should not be used to add fixed labels to all metrics |
| 36 | // exposed. See also |
| 37 | // https://prometheus.io/docs/instrumenting/writing_exporters/#target-labels-not-static-scraped-labels |
khenaidoo | ab1f7bd | 2019-11-14 14:00:27 -0500 | [diff] [blame] | 38 | // |
| 39 | // Conflicts between Collectors registered through the original Registerer with |
| 40 | // Collectors registered through the wrapping Registerer will still be |
| 41 | // detected. Any AlreadyRegisteredError returned by the Register method of |
| 42 | // either Registerer will contain the ExistingCollector in the form it was |
| 43 | // provided to the respective registry. |
| 44 | // |
| 45 | // The Collector example demonstrates a use of WrapRegistererWith. |
| 46 | func WrapRegistererWith(labels Labels, reg Registerer) Registerer { |
| 47 | return &wrappingRegisterer{ |
| 48 | wrappedRegisterer: reg, |
| 49 | labels: labels, |
| 50 | } |
| 51 | } |
| 52 | |
| 53 | // WrapRegistererWithPrefix returns a Registerer wrapping the provided |
| 54 | // Registerer. Collectors registered with the returned Registerer will be |
| 55 | // registered with the wrapped Registerer in a modified way. The modified |
| 56 | // Collector adds the provided prefix to the name of all Metrics it collects. |
khenaidoo | d948f77 | 2021-08-11 17:49:24 -0400 | [diff] [blame^] | 57 | // Wrapping a nil value is valid, resulting in a no-op Registerer. |
khenaidoo | ab1f7bd | 2019-11-14 14:00:27 -0500 | [diff] [blame] | 58 | // |
| 59 | // WrapRegistererWithPrefix is useful to have one place to prefix all metrics of |
| 60 | // a sub-system. To make this work, register metrics of the sub-system with the |
| 61 | // wrapping Registerer returned by WrapRegistererWithPrefix. It is rarely useful |
| 62 | // to use the same prefix for all metrics exposed. In particular, do not prefix |
| 63 | // metric names that are standardized across applications, as that would break |
| 64 | // horizontal monitoring, for example the metrics provided by the Go collector |
| 65 | // (see NewGoCollector) and the process collector (see NewProcessCollector). (In |
| 66 | // fact, those metrics are already prefixed with “go_” or “process_”, |
| 67 | // respectively.) |
| 68 | // |
| 69 | // Conflicts between Collectors registered through the original Registerer with |
| 70 | // Collectors registered through the wrapping Registerer will still be |
| 71 | // detected. Any AlreadyRegisteredError returned by the Register method of |
| 72 | // either Registerer will contain the ExistingCollector in the form it was |
| 73 | // provided to the respective registry. |
| 74 | func WrapRegistererWithPrefix(prefix string, reg Registerer) Registerer { |
| 75 | return &wrappingRegisterer{ |
| 76 | wrappedRegisterer: reg, |
| 77 | prefix: prefix, |
| 78 | } |
| 79 | } |
| 80 | |
| 81 | type wrappingRegisterer struct { |
| 82 | wrappedRegisterer Registerer |
| 83 | prefix string |
| 84 | labels Labels |
| 85 | } |
| 86 | |
| 87 | func (r *wrappingRegisterer) Register(c Collector) error { |
khenaidoo | d948f77 | 2021-08-11 17:49:24 -0400 | [diff] [blame^] | 88 | if r.wrappedRegisterer == nil { |
| 89 | return nil |
| 90 | } |
khenaidoo | ab1f7bd | 2019-11-14 14:00:27 -0500 | [diff] [blame] | 91 | return r.wrappedRegisterer.Register(&wrappingCollector{ |
| 92 | wrappedCollector: c, |
| 93 | prefix: r.prefix, |
| 94 | labels: r.labels, |
| 95 | }) |
| 96 | } |
| 97 | |
| 98 | func (r *wrappingRegisterer) MustRegister(cs ...Collector) { |
khenaidoo | d948f77 | 2021-08-11 17:49:24 -0400 | [diff] [blame^] | 99 | if r.wrappedRegisterer == nil { |
| 100 | return |
| 101 | } |
khenaidoo | ab1f7bd | 2019-11-14 14:00:27 -0500 | [diff] [blame] | 102 | for _, c := range cs { |
| 103 | if err := r.Register(c); err != nil { |
| 104 | panic(err) |
| 105 | } |
| 106 | } |
| 107 | } |
| 108 | |
| 109 | func (r *wrappingRegisterer) Unregister(c Collector) bool { |
khenaidoo | d948f77 | 2021-08-11 17:49:24 -0400 | [diff] [blame^] | 110 | if r.wrappedRegisterer == nil { |
| 111 | return false |
| 112 | } |
khenaidoo | ab1f7bd | 2019-11-14 14:00:27 -0500 | [diff] [blame] | 113 | return r.wrappedRegisterer.Unregister(&wrappingCollector{ |
| 114 | wrappedCollector: c, |
| 115 | prefix: r.prefix, |
| 116 | labels: r.labels, |
| 117 | }) |
| 118 | } |
| 119 | |
| 120 | type wrappingCollector struct { |
| 121 | wrappedCollector Collector |
| 122 | prefix string |
| 123 | labels Labels |
| 124 | } |
| 125 | |
| 126 | func (c *wrappingCollector) Collect(ch chan<- Metric) { |
| 127 | wrappedCh := make(chan Metric) |
| 128 | go func() { |
| 129 | c.wrappedCollector.Collect(wrappedCh) |
| 130 | close(wrappedCh) |
| 131 | }() |
| 132 | for m := range wrappedCh { |
| 133 | ch <- &wrappingMetric{ |
| 134 | wrappedMetric: m, |
| 135 | prefix: c.prefix, |
| 136 | labels: c.labels, |
| 137 | } |
| 138 | } |
| 139 | } |
| 140 | |
| 141 | func (c *wrappingCollector) Describe(ch chan<- *Desc) { |
| 142 | wrappedCh := make(chan *Desc) |
| 143 | go func() { |
| 144 | c.wrappedCollector.Describe(wrappedCh) |
| 145 | close(wrappedCh) |
| 146 | }() |
| 147 | for desc := range wrappedCh { |
| 148 | ch <- wrapDesc(desc, c.prefix, c.labels) |
| 149 | } |
| 150 | } |
| 151 | |
| 152 | func (c *wrappingCollector) unwrapRecursively() Collector { |
| 153 | switch wc := c.wrappedCollector.(type) { |
| 154 | case *wrappingCollector: |
| 155 | return wc.unwrapRecursively() |
| 156 | default: |
| 157 | return wc |
| 158 | } |
| 159 | } |
| 160 | |
| 161 | type wrappingMetric struct { |
| 162 | wrappedMetric Metric |
| 163 | prefix string |
| 164 | labels Labels |
| 165 | } |
| 166 | |
| 167 | func (m *wrappingMetric) Desc() *Desc { |
| 168 | return wrapDesc(m.wrappedMetric.Desc(), m.prefix, m.labels) |
| 169 | } |
| 170 | |
| 171 | func (m *wrappingMetric) Write(out *dto.Metric) error { |
| 172 | if err := m.wrappedMetric.Write(out); err != nil { |
| 173 | return err |
| 174 | } |
| 175 | if len(m.labels) == 0 { |
| 176 | // No wrapping labels. |
| 177 | return nil |
| 178 | } |
| 179 | for ln, lv := range m.labels { |
| 180 | out.Label = append(out.Label, &dto.LabelPair{ |
| 181 | Name: proto.String(ln), |
| 182 | Value: proto.String(lv), |
| 183 | }) |
| 184 | } |
| 185 | sort.Sort(labelPairSorter(out.Label)) |
| 186 | return nil |
| 187 | } |
| 188 | |
| 189 | func wrapDesc(desc *Desc, prefix string, labels Labels) *Desc { |
| 190 | constLabels := Labels{} |
| 191 | for _, lp := range desc.constLabelPairs { |
| 192 | constLabels[*lp.Name] = *lp.Value |
| 193 | } |
| 194 | for ln, lv := range labels { |
| 195 | if _, alreadyUsed := constLabels[ln]; alreadyUsed { |
| 196 | return &Desc{ |
| 197 | fqName: desc.fqName, |
| 198 | help: desc.help, |
| 199 | variableLabels: desc.variableLabels, |
| 200 | constLabelPairs: desc.constLabelPairs, |
| 201 | err: fmt.Errorf("attempted wrapping with already existing label name %q", ln), |
| 202 | } |
| 203 | } |
| 204 | constLabels[ln] = lv |
| 205 | } |
| 206 | // NewDesc will do remaining validations. |
| 207 | newDesc := NewDesc(prefix+desc.fqName, desc.help, desc.variableLabels, constLabels) |
| 208 | // Propagate errors if there was any. This will override any errer |
| 209 | // created by NewDesc above, i.e. earlier errors get precedence. |
| 210 | if desc.err != nil { |
| 211 | newDesc.err = desc.err |
| 212 | } |
| 213 | return newDesc |
| 214 | } |