feat(inputs.prometheus): use system wide proxy settings (#11729)

plugins/inputs/prometheus/README.md

@@ -91,6 +91,10 @@ in Prometheus format.
   
   ## Specify timeout duration for slower prometheus clients (default is 3s)
   # response_timeout = "3s"
+
+  ## HTTP Proxy support
+  # use_system_proxy = false
+  # http_proxy_url = ""
   
   ## Optional TLS Config
   # tls_ca = /path/to/cafile

plugins/inputs/prometheus/prometheus.go

@@ -21,7 +21,7 @@ import (
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/config"
 	"github.com/influxdata/telegraf/internal"
-	"github.com/influxdata/telegraf/plugins/common/tls"
+	httpconfig "github.com/influxdata/telegraf/plugins/common/http"
 	"github.com/influxdata/telegraf/plugins/inputs"
 	parserV2 "github.com/influxdata/telegraf/plugins/parsers/prometheus"
 )
@@ -66,10 +66,10 @@ type Prometheus struct {
 
 	IgnoreTimestamp bool `toml:"ignore_timestamp"`
 
-	tls.ClientConfig
-
 	Log telegraf.Logger
 
+	httpconfig.HTTPClientConfig
+
 	client  *http.Client
 	headers map[string]string
 
@@ -138,6 +138,17 @@ func (p *Prometheus) Init() error {
 		p.Log.Infof("Using the label selector: %v and field selector: %v", p.podLabelSelector, p.podFieldSelector)
 	}
 
+	ctx := context.Background()
+	client, err := p.HTTPClientConfig.CreateClient(ctx, p.Log)
+	if err != nil {
+		return err
+	}
+	p.client = client
+	p.headers = map[string]string{
+		"User-Agent": internal.ProductToken(),
+		"Accept":     acceptHeader,
+	}
+
 	return nil
 }
 
@@ -215,18 +226,6 @@ func (p *Prometheus) GetAllURLs() (map[string]URLAndAddress, error) {
 // Reads stats from all configured servers accumulates stats.
 // Returns one of the errors encountered while gather stats (if any).
 func (p *Prometheus) Gather(acc telegraf.Accumulator) error {
-	if p.client == nil {
-		client, err := p.createHTTPClient()
-		if err != nil {
-			return err
-		}
-		p.client = client
-		p.headers = map[string]string{
-			"User-Agent": internal.ProductToken(),
-			"Accept":     acceptHeader,
-		}
-	}
-
 	var wg sync.WaitGroup
 
 	allURLs, err := p.GetAllURLs()
@@ -246,23 +245,6 @@ func (p *Prometheus) Gather(acc telegraf.Accumulator) error {
 	return nil
 }
 
-func (p *Prometheus) createHTTPClient() (*http.Client, error) {
-	tlsCfg, err := p.ClientConfig.TLSConfig()
-	if err != nil {
-		return nil, err
-	}
-
-	client := &http.Client{
-		Transport: &http.Transport{
-			TLSClientConfig:   tlsCfg,
-			DisableKeepAlives: true,
-		},
-		Timeout: time.Duration(p.ResponseTimeout),
-	}
-
-	return client, nil
-}
-
 func (p *Prometheus) gatherURL(u URLAndAddress, acc telegraf.Accumulator) error {
 	var req *http.Request
 	var err error
@@ -280,7 +262,7 @@ func (p *Prometheus) gatherURL(u URLAndAddress, acc telegraf.Accumulator) error
 		}
 
 		// ignore error because it's been handled before getting here
-		tlsCfg, _ := p.ClientConfig.TLSConfig()
+		tlsCfg, _ := p.HTTPClientConfig.TLSConfig()
 		uClient = &http.Client{
 			Transport: &http.Transport{
 				TLSClientConfig:   tlsCfg,

plugins/inputs/prometheus/prometheus_test.go

@@ -60,10 +60,12 @@ func TestPrometheusGeneratesMetrics(t *testing.T) {
 		URLs:   []string{ts.URL},
 		URLTag: "url",
 	}
+	err := p.Init()
+	require.NoError(t, err)
 
 	var acc testutil.Accumulator
 
-	err := acc.GatherError(p.Gather)
+	err = acc.GatherError(p.Gather)
 	require.NoError(t, err)
 
 	require.True(t, acc.HasFloatField("go_gc_duration_seconds", "count"))
@@ -86,12 +88,15 @@ func TestPrometheusGeneratesMetricsWithHostNameTag(t *testing.T) {
 		KubernetesServices: []string{ts.URL},
 		URLTag:             "url",
 	}
+	err := p.Init()
+	require.NoError(t, err)
+
 	u, _ := url.Parse(ts.URL)
 	tsAddress := u.Hostname()
 
 	var acc testutil.Accumulator
 
-	err := acc.GatherError(p.Gather)
+	err = acc.GatherError(p.Gather)
 	require.NoError(t, err)
 
 	require.True(t, acc.HasFloatField("go_gc_duration_seconds", "count"))
@@ -118,10 +123,12 @@ func TestPrometheusGeneratesMetricsAlthoughFirstDNSFailsIntegration(t *testing.T
 		URLs:               []string{ts.URL},
 		KubernetesServices: []string{"http://random.telegraf.local:88/metrics"},
 	}
+	err := p.Init()
+	require.NoError(t, err)
 
 	var acc testutil.Accumulator
 
-	err := acc.GatherError(p.Gather)
+	err = acc.GatherError(p.Gather)
 	require.NoError(t, err)
 
 	require.True(t, acc.HasFloatField("go_gc_duration_seconds", "count"))
@@ -142,10 +149,12 @@ func TestPrometheusGeneratesSummaryMetricsV2(t *testing.T) {
 		URLTag:        "url",
 		MetricVersion: 2,
 	}
+	err := p.Init()
+	require.NoError(t, err)
 
 	var acc testutil.Accumulator
 
-	err := acc.GatherError(p.Gather)
+	err = acc.GatherError(p.Gather)
 	require.NoError(t, err)
 
 	require.True(t, acc.TagSetValue("prometheus", "quantile") == "0")
@@ -173,10 +182,12 @@ go_gc_duration_seconds_count 42`
 		URLTag:        "",
 		MetricVersion: 2,
 	}
+	err := p.Init()
+	require.NoError(t, err)
 
 	var acc testutil.Accumulator
 
-	err := p.Gather(&acc)
+	err = p.Gather(&acc)
 	require.NoError(t, err)
 
 	expected := []telegraf.Metric{
@@ -230,10 +241,12 @@ func TestPrometheusGeneratesGaugeMetricsV2(t *testing.T) {
 		URLTag:        "url",
 		MetricVersion: 2,
 	}
+	err := p.Init()
+	require.NoError(t, err)
 
 	var acc testutil.Accumulator
 
-	err := acc.GatherError(p.Gather)
+	err = acc.GatherError(p.Gather)
 	require.NoError(t, err)
 
 	require.True(t, acc.HasFloatField("prometheus", "go_goroutines"))
@@ -254,10 +267,12 @@ func TestPrometheusGeneratesMetricsWithIgnoreTimestamp(t *testing.T) {
 		URLTag:          "url",
 		IgnoreTimestamp: true,
 	}
+	err := p.Init()
+	require.NoError(t, err)
 
 	var acc testutil.Accumulator
 
-	err := acc.GatherError(p.Gather)
+	err = acc.GatherError(p.Gather)
 	require.NoError(t, err)
 
 	m, _ := acc.Get("test_metric")

plugins/inputs/prometheus/sample.conf

@@ -83,6 +83,10 @@
   
   ## Specify timeout duration for slower prometheus clients (default is 3s)
   # response_timeout = "3s"
+
+  ## HTTP Proxy support
+  # use_system_proxy = false
+  # http_proxy_url = ""
   
   ## Optional TLS Config
   # tls_ca = /path/to/cafile

plugins/outputs/prometheus_client/prometheus_client_v1_test.go

@@ -364,8 +364,11 @@ rpc_duration_seconds_count 2693
 				URLTag:        "",
 				MetricVersion: 1,
 			}
+			err := input.Init()
+			require.NoError(t, err)
+
 			var acc testutil.Accumulator
-			err := input.Start(&acc)
+			err = input.Start(&acc)
 			require.NoError(t, err)
 			err = input.Gather(&acc)
 			require.NoError(t, err)

plugins/outputs/prometheus_client/prometheus_client_v2_test.go

@@ -424,8 +424,11 @@ rpc_duration_seconds_count 2693
 				URLTag:        "",
 				MetricVersion: 2,
 			}
+			err := input.Init()
+			require.NoError(t, err)
+
 			var acc testutil.Accumulator
-			err := input.Start(&acc)
+			err = input.Start(&acc)
 			require.NoError(t, err)
 			err = input.Gather(&acc)
 			require.NoError(t, err)