feat: add nomad input plugin

plugins/inputs/all/all.go

@@ -127,6 +127,7 @@ import (
 	_ "github.com/influxdata/telegraf/plugins/inputs/nginx_sts"
 	_ "github.com/influxdata/telegraf/plugins/inputs/nginx_upstream_check"
 	_ "github.com/influxdata/telegraf/plugins/inputs/nginx_vts"
+	_ "github.com/influxdata/telegraf/plugins/inputs/nomad"
 	_ "github.com/influxdata/telegraf/plugins/inputs/nsd"
 	_ "github.com/influxdata/telegraf/plugins/inputs/nsq"
 	_ "github.com/influxdata/telegraf/plugins/inputs/nsq_consumer"

plugins/inputs/nomad/README.md

@@ -0,0 +1,39 @@
+# Nomad Input Plugin
+
+The Nomad plugin must grab metrics from every Nomad agent of the cluster. Telegraf may be present in every node and connect to the agent locally. In this case should be something like `http://127.0.0.1:4646`.
+
+> Tested on Nomad 1.1.6
+
+### Configuration
+
+```toml
+[[inputs.nomad]]
+  ## URL for the Nomad agent
+  url = "http://127.0.0.1:4646"
+
+  ## Use auth token for authorization. ('auth_token' takes priority)
+  ## If both of these are empty, no token will be used.
+  # auth_token = "/path/to/auth/token"
+  ## OR
+  # auth_token_string = "a1234567-40c7-9048-7bae-378687048181"
+
+  ## Labels to be added as tags. An empty array for both include and
+  ## exclude will include all labels.
+  # label_include = []
+  # label_exclude = ["*"]
+
+  ## Set response_timeout (default 5 seconds)
+  # response_timeout = "5s"
+
+  ## Optional TLS Config
+  # tls_ca = /path/to/cafile
+  # tls_cert = /path/to/certfile
+  # tls_key = /path/to/keyfile
+```
+
+
+### Metrics
+
+Both Nomad servers and agents collect various metrics, for every details please have a look at Nomad documentation, here:
+- [https://www.nomadproject.io/docs/operations/metrics](https://www.nomadproject.io/docs/operations/metrics)
+- [https://www.nomadproject.io/docs/operations/telemetry](https://www.nomadproject.io/docs/operations/telemetry)

plugins/inputs/nomad/nomad.go

@@ -0,0 +1,215 @@
+package nomad
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/config"
+	"github.com/influxdata/telegraf/filter"
+	"github.com/influxdata/telegraf/plugins/common/tls"
+	"github.com/influxdata/telegraf/plugins/inputs"
+)
+
+type Nomad struct {
+	URL string
+
+	AuthToken       string `toml:"auth_token"`
+	AuthTokenString string `toml:"auth_token_string"`
+
+	LabelInclude []string `toml:"label_include"`
+	LabelExclude []string `toml:"label_exclude"`
+
+	labelFilter filter.Filter
+
+	ResponseTimeout config.Duration
+
+	tls.ClientConfig
+
+	RoundTripper http.RoundTripper
+}
+
+const timeLayout = "2006-01-02 15:04:05 -0700 MST"
+
+var sampleConfig = `
+  ## URL for the Nomad agent
+  url = "http://127.0.0.1:4646"
+
+  ## Use auth token for authorization. ('auth_token' takes priority)
+  ## If both of these are empty, no token will be used.
+  # auth_token = "/path/to/auth/token"
+  ## OR
+  # auth_token_string = "a1234567-40c7-9048-7bae-378687048181"
+
+  ## Labels to be added as tags. An empty array for both include and
+  ## exclude will include all labels.
+  # label_include = []
+  # label_exclude = ["*"]
+
+  ## Set response_timeout (default 5 seconds)
+  # response_timeout = "5s"
+
+  ## Optional TLS Config
+  # tls_ca = /path/to/cafile
+  # tls_cert = /path/to/certfile
+  # tls_key = /path/to/keyfile
+`
+
+func init() {
+	inputs.Add("nomad", func() telegraf.Input {
+		return &Nomad{
+			LabelInclude: []string{},
+			LabelExclude: []string{"*"},
+		}
+	})
+}
+
+func (n *Nomad) SampleConfig() string {
+	return sampleConfig
+}
+
+func (n *Nomad) Description() string {
+	return "Read metrics from the Nomad api"
+}
+
+func (n *Nomad) Init() error {
+	if n.AuthToken == "" && n.AuthTokenString == "" {
+		n.AuthToken = ""
+	}
+
+	if n.AuthToken != "" {
+		token, err := os.ReadFile(n.AuthToken)
+		if err != nil {
+			return err
+		}
+		n.AuthTokenString = strings.TrimSpace(string(token))
+	}
+
+	labelFilter, err := filter.NewIncludeExcludeFilter(n.LabelInclude, n.LabelExclude)
+	if err != nil {
+		return err
+	}
+	n.labelFilter = labelFilter
+
+	return nil
+}
+
+func (n *Nomad) Gather(acc telegraf.Accumulator) error {
+	acc.AddError(n.gatherSummary(n.URL, acc))
+	return nil
+}
+
+func (n *Nomad) gatherSummary(baseURL string, acc telegraf.Accumulator) error {
+	summaryMetrics := &MetricsSummary{}
+	err := n.LoadJSON(fmt.Sprintf("%s/v1/metrics", baseURL), summaryMetrics)
+	if err != nil {
+		return err
+	}
+
+	buildNomadMetrics(summaryMetrics, acc)
+
+	return nil
+}
+
+func (n *Nomad) LoadJSON(url string, v interface{}) error {
+	var req, err = http.NewRequest("GET", url, nil)
+	if err != nil {
+		return err
+	}
+	var resp *http.Response
+	tlsCfg, err := n.ClientConfig.TLSConfig()
+	if err != nil {
+		return err
+	}
+	if n.RoundTripper == nil {
+		if n.ResponseTimeout < config.Duration(time.Second) {
+			n.ResponseTimeout = config.Duration(time.Second * 5)
+		}
+		n.RoundTripper = &http.Transport{
+			TLSHandshakeTimeout:   5 * time.Second,
+			TLSClientConfig:       tlsCfg,
+			ResponseHeaderTimeout: time.Duration(n.ResponseTimeout),
+		}
+	}
+	req.Header.Set("Authorization", "X-Nomad-Token "+n.AuthTokenString)
+	req.Header.Add("Accept", "application/json")
+	resp, err = n.RoundTripper.RoundTrip(req)
+	if err != nil {
+		return fmt.Errorf("error making HTTP request to %s: %s", url, err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("%s returned HTTP status %s", url, resp.Status)
+	}
+
+	err = json.NewDecoder(resp.Body).Decode(v)
+	if err != nil {
+		return fmt.Errorf(`error parsing response: %s`, err)
+	}
+
+	return nil
+}
+
+func buildNomadMetrics(summaryMetrics *MetricsSummary, acc telegraf.Accumulator) {
+
+	t, err := time.Parse(timeLayout, summaryMetrics.Timestamp)
+	if err != nil {
+		panic(err)
+	}
+	sampledValueFields := make(map[string]interface{})
+
+	for c, counters := range summaryMetrics.Counters {
+		tags := summaryMetrics.Counters[c].DisplayLabels
+
+		sampledValueFields["count"] = counters.Count
+		sampledValueFields["rate"] = counters.Rate
+		sampledValueFields["sum"] = counters.Sum
+		sampledValueFields["sumsq"] = counters.SumSq
+		sampledValueFields["min"] = counters.Min
+		sampledValueFields["max"] = counters.Max
+		sampledValueFields["mean"] = counters.Mean
+
+		acc.AddCounter(counters.Name, sampledValueFields, tags, t)
+	}
+
+	for c, gauges := range summaryMetrics.Gauges {
+		tags := summaryMetrics.Gauges[c].DisplayLabels
+
+		fields := make(map[string]interface{})
+		fields["value"] = gauges.Value
+
+		t, err := time.Parse(timeLayout, summaryMetrics.Timestamp)
+		if err != nil {
+			panic(err)
+		}
+		acc.AddGauge(gauges.Name, fields, tags, t)
+	}
+
+	for _, points := range summaryMetrics.Points {
+		tags := make(map[string]string)
+
+		fields := make(map[string]interface{})
+		fields["value"] = points.Points
+
+		acc.AddFields(points.Name, fields, tags, t)
+	}
+
+	for c, samples := range summaryMetrics.Samples {
+		tags := summaryMetrics.Samples[c].DisplayLabels
+
+		sampledValueFields := make(map[string]interface{})
+		sampledValueFields["count"] = samples.Count
+		sampledValueFields["rate"] = samples.Rate
+		sampledValueFields["sum"] = samples.Sum
+		sampledValueFields["sumsq"] = samples.SumSq
+		sampledValueFields["min"] = samples.Min
+		sampledValueFields["max"] = samples.Max
+		sampledValueFields["mean"] = samples.Mean
+
+		acc.AddCounter(samples.Name, sampledValueFields, tags, t)
+	}
+}

plugins/inputs/nomad/nomad_metrics.go

@@ -0,0 +1,53 @@
+package nomad
+
+import (
+	"time"
+)
+
+type MetricsSummary struct {
+	Timestamp string
+	Gauges    []GaugeValue
+	Points    []PointValue
+	Counters  []SampledValue
+	Samples   []SampledValue
+}
+
+type GaugeValue struct {
+	Name  string
+	Hash  string `json:"-"`
+	Value float32
+
+	Labels        []Label           `json:"-"`
+	DisplayLabels map[string]string `json:"Labels"`
+}
+
+type PointValue struct {
+	Name   string
+	Points []float32
+}
+
+type SampledValue struct {
+	Name string
+	Hash string `json:"-"`
+	*AggregateSample
+	Mean   float64
+	Stddev float64
+
+	Labels        []Label           `json:"-"`
+	DisplayLabels map[string]string `json:"Labels"`
+}
+
+type AggregateSample struct {
+	Count       int
+	Rate        float64
+	Sum         float64
+	SumSq       float64 `json:"-"`
+	Min         float64
+	Max         float64
+	LastUpdated time.Time `json:"-"`
+}
+
+type Label struct {
+	Name  string
+	Value string
+}