133 lines
3.4 KiB
Markdown
133 lines
3.4 KiB
Markdown
### Aggregator Plugins
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This section is for developers who want to create a new aggregator plugin.
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### Aggregator Plugin Guidelines
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* A aggregator must conform to the [telegraf.Aggregator][] interface.
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* Aggregators should call `aggregators.Add` in their `init` function to
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register themselves. See below for a quick example.
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* To be available within Telegraf itself, plugins must add themselves to the
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`github.com/influxdata/telegraf/plugins/aggregators/all/all.go` file.
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- The `SampleConfig` function should return valid toml that describes how the
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plugin can be configured. This is included in `telegraf config`. Please
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consult the [SampleConfig][] page for the latest style guidelines.
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* The `Description` function should say in one line what this aggregator does.
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* The Aggregator plugin will need to keep caches of metrics that have passed
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through it. This should be done using the builtin `HashID()` function of
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each metric.
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* When the `Reset()` function is called, all caches should be cleared.
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- Follow the recommended [CodeStyle][].
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### Aggregator Plugin Example
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```go
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package min
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// min.go
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import (
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"github.com/influxdata/telegraf"
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"github.com/influxdata/telegraf/plugins/aggregators"
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)
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type Min struct {
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// caches for metric fields, names, and tags
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fieldCache map[uint64]map[string]float64
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nameCache map[uint64]string
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tagCache map[uint64]map[string]string
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}
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func NewMin() telegraf.Aggregator {
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m := &Min{}
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m.Reset()
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return m
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}
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var sampleConfig = `
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## period is the flush & clear interval of the aggregator.
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period = "30s"
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## If true drop_original will drop the original metrics and
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## only send aggregates.
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drop_original = false
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`
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func (m *Min) Init() error {
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return nil
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}
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func (m *Min) SampleConfig() string {
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return sampleConfig
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}
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func (m *Min) Description() string {
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return "Keep the aggregate min of each metric passing through."
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}
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func (m *Min) Add(in telegraf.Metric) {
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id := in.HashID()
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if _, ok := m.nameCache[id]; !ok {
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// hit an uncached metric, create caches for first time:
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m.nameCache[id] = in.Name()
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m.tagCache[id] = in.Tags()
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m.fieldCache[id] = make(map[string]float64)
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for k, v := range in.Fields() {
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if fv, ok := convert(v); ok {
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m.fieldCache[id][k] = fv
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}
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}
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} else {
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for k, v := range in.Fields() {
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if fv, ok := convert(v); ok {
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if _, ok := m.fieldCache[id][k]; !ok {
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// hit an uncached field of a cached metric
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m.fieldCache[id][k] = fv
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continue
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}
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if fv < m.fieldCache[id][k] {
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// set new minimum
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m.fieldCache[id][k] = fv
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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 (m *Min) Push(acc telegraf.Accumulator) {
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for id, _ := range m.nameCache {
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fields := map[string]interface{}{}
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for k, v := range m.fieldCache[id] {
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fields[k+"_min"] = v
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}
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acc.AddFields(m.nameCache[id], fields, m.tagCache[id])
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}
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}
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func (m *Min) Reset() {
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m.fieldCache = make(map[uint64]map[string]float64)
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m.nameCache = make(map[uint64]string)
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m.tagCache = make(map[uint64]map[string]string)
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}
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func convert(in interface{}) (float64, bool) {
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switch v := in.(type) {
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case float64:
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return v, true
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case int64:
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return float64(v), true
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default:
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return 0, false
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}
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}
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func init() {
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aggregators.Add("min", func() telegraf.Aggregator {
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return NewMin()
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})
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}
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```
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[telegraf.Aggregator]: https://godoc.org/github.com/influxdata/telegraf#Aggregator
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[SampleConfig]: https://github.com/influxdata/telegraf/wiki/SampleConfig
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[CodeStyle]: https://github.com/influxdata/telegraf/wiki/CodeStyle
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