Add support for sending HTTP Basic Auth in influxdb input (#6668)

plugins/inputs/influxdb/README.md

@@ -20,6 +20,10 @@ InfluxDB-formatted endpoints. See below for more information.
     "http://localhost:8086/debug/vars"
   ]
 
+  ## Username and password to send using HTTP Basic Authentication.
+  # username = ""
+  # password = ""
+
   ## Optional TLS Config
   # tls_ca = "/etc/telegraf/ca.pem"
   # tls_cert = "/etc/telegraf/cert.pem"

plugins/inputs/influxdb/influxdb.go

@@ -1,9 +1,10 @@
 package influxdb
 
 import (
+	"bytes"
 	"encoding/json"
 	"errors"
-	"fmt"
+	"io"
 	"net/http"
 	"sync"
 	"time"
@@ -14,9 +15,28 @@ import (
 	"github.com/influxdata/telegraf/plugins/inputs"
 )
 
+const (
+	maxErrorResponseBodyLength = 1024
+)
+
+type APIError struct {
+	StatusCode  int
+	Reason      string
+	Description string `json:"error"`
+}
+
+func (e *APIError) Error() string {
+	if e.Description != "" {
+		return e.Reason + ": " + e.Description
+	}
+	return e.Reason
+}
+
 type InfluxDB struct {
 	URLs     []string          `toml:"urls"`
-	Timeout internal.Duration
+	Username string            `toml:"username"`
+	Password string            `toml:"password"`
+	Timeout  internal.Duration `toml:"timeout"`
 	tls.ClientConfig
 
 	client *http.Client
@@ -38,6 +58,10 @@ func (*InfluxDB) SampleConfig() string {
     "http://localhost:8086/debug/vars"
   ]
 
+  ## Username and password to send using HTTP Basic Authentication.
+  # username = ""
+  # password = ""
+
   ## Optional TLS Config
   # tls_ca = "/etc/telegraf/ca.pem"
   # tls_cert = "/etc/telegraf/cert.pem"
@@ -75,7 +99,7 @@ func (i *InfluxDB) Gather(acc telegraf.Accumulator) error {
 		go func(url string) {
 			defer wg.Done()
 			if err := i.gatherURL(acc, url); err != nil {
-				acc.AddError(fmt.Errorf("[url=%s]: %s", url, err))
+				acc.AddError(err)
 			}
 		}(u)
 	}
@@ -135,12 +159,27 @@ func (i *InfluxDB) gatherURL(
 	shardCounter := 0
 	now := time.Now()
 
-	resp, err := i.client.Get(url)
+	req, err := http.NewRequest("GET", url, nil)
+	if err != nil {
+		return err
+	}
+
+	if i.Username != "" || i.Password != "" {
+		req.SetBasicAuth(i.Username, i.Password)
+	}
+
+	req.Header.Set("User-Agent", "Telegraf/"+internal.Version())
+
+	resp, err := i.client.Do(req)
 	if err != nil {
 		return err
 	}
 	defer resp.Body.Close()
 
+	if resp.StatusCode != http.StatusOK {
+		return readResponseError(resp)
+	}
+
 	// It would be nice to be able to decode into a map[string]point, but
 	// we'll get a decoder error like:
 	// `json: cannot unmarshal array into Go value of type influxdb.point`
@@ -255,6 +294,27 @@ func (i *InfluxDB) gatherURL(
 	return nil
 }
 
+func readResponseError(resp *http.Response) error {
+	apiError := &APIError{
+		StatusCode: resp.StatusCode,
+		Reason:     resp.Status,
+	}
+
+	var buf bytes.Buffer
+	r := io.LimitReader(resp.Body, maxErrorResponseBodyLength)
+	_, err := buf.ReadFrom(r)
+	if err != nil {
+		return apiError
+	}
+
+	err = json.Unmarshal(buf.Bytes(), apiError)
+	if err != nil {
+		return apiError
+	}
+
+	return apiError
+}
+
 func init() {
 	inputs.Add("influxdb", func() telegraf.Input {
 		return &InfluxDB{

plugins/inputs/influxdb/influxdb_test.go

@@ -1,6 +1,7 @@
 package influxdb_test
 
 import (
+	"fmt"
 	"net/http"
 	"net/http/httptest"
 	"testing"
@@ -178,6 +179,31 @@ func TestErrorHandling404(t *testing.T) {
 	require.Error(t, acc.GatherError(plugin.Gather))
 }
 
+func TestErrorResponse(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusUnauthorized)
+		w.Write([]byte(`{"error": "unable to parse authentication credentials"}`))
+	}))
+	defer ts.Close()
+
+	plugin := &influxdb.InfluxDB{
+		URLs: []string{ts.URL},
+	}
+
+	var acc testutil.Accumulator
+	err := plugin.Gather(&acc)
+	require.NoError(t, err)
+
+	expected := []error{
+		&influxdb.APIError{
+			StatusCode:  http.StatusUnauthorized,
+			Reason:      fmt.Sprintf("%d %s", http.StatusUnauthorized, http.StatusText(http.StatusUnauthorized)),
+			Description: "unable to parse authentication credentials",
+		},
+	}
+	require.Equal(t, expected, acc.Errors)
+}
+
 const basicJSON = `
 {
   "_1": {