Respect path prefix in influx output uri (#3224)

(cherry picked from commit 9c8f4afa37)

etc/telegraf.conf

@@ -84,9 +84,7 @@
 
 # Configuration for influxdb server to send metrics to
 [[outputs.influxdb]]
-  ## The HTTP or UDP URL for your InfluxDB instance.  Each item should be
-  ## of the form:
-  ##   scheme "://" host [ ":" port]
+  ## The full HTTP or UDP URL for your InfluxDB instance.
   ##
   ## Multiple urls can be specified as part of the same cluster,
   ## this means that only ONE of the urls will be written to each interval.

plugins/outputs/influxdb/README.md

@@ -7,9 +7,7 @@ This plugin writes to [InfluxDB](https://www.influxdb.com) via HTTP or UDP.
 ```toml
 # Configuration for influxdb server to send metrics to
 [[outputs.influxdb]]
-  ## The HTTP or UDP URL for your InfluxDB instance.  Each item should be
-  ## of the form:
-  ##   scheme "://" host [ ":" port]
+  ## The full HTTP or UDP URL for your InfluxDB instance.
   ##
   ## Multiple urls can be specified as part of the same cluster,
   ## this means that only ONE of the urls will be written to each interval.

plugins/outputs/influxdb/client/http.go

@@ -10,6 +10,7 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/url"
+	"path"
 	"time"
 )
 
@@ -255,8 +256,11 @@ func writeURL(u *url.URL, wp WriteParams) string {
 	}
 
 	u.RawQuery = params.Encode()
-	u.Path = "write"
-	return u.String()
+	p := u.Path
+	u.Path = path.Join(p, "write")
+	s := u.String()
+	u.Path = p
+	return s
 }
 
 func queryURL(u *url.URL, command string) string {
@@ -264,6 +268,9 @@ func queryURL(u *url.URL, command string) string {
 	params.Set("q", command)
 
 	u.RawQuery = params.Encode()
-	u.Path = "query"
-	return u.String()
+	p := u.Path
+	u.Path = path.Join(p, "query")
+	s := u.String()
+	u.Path = p
+	return s
 }

plugins/outputs/influxdb/client/http_test.go

@@ -299,3 +299,37 @@ func TestGzipCompression(t *testing.T) {
 
 	assert.Equal(t, []byte(influxLine), uncompressed.Bytes())
 }
+
+func TestHTTPClient_PathPrefix(t *testing.T) {
+	prefix := "/some/random/prefix"
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case prefix + "/write":
+			w.WriteHeader(http.StatusNoContent)
+			w.Header().Set("Content-Type", "application/json")
+		case prefix + "/query":
+			w.WriteHeader(http.StatusOK)
+			w.Header().Set("Content-Type", "application/json")
+			fmt.Fprintln(w, `{"results":[{}]}`)
+		default:
+			w.WriteHeader(http.StatusNotFound)
+			msg := fmt.Sprintf("Path not found: %s", r.URL.Path)
+			fmt.Fprintln(w, msg)
+		}
+	}))
+	defer ts.Close()
+
+	config := HTTPConfig{
+		URL: ts.URL + prefix,
+	}
+	wp := WriteParams{
+		Database: "test",
+	}
+	client, err := NewHTTP(config, wp)
+	defer client.Close()
+	assert.NoError(t, err)
+	err = client.Query("CREATE DATABASE test")
+	assert.NoError(t, err)
+	err = client.WriteStream(bytes.NewReader([]byte("cpu value=99\n")))
+	assert.NoError(t, err)
+}

plugins/outputs/influxdb/influxdb.go

@@ -53,9 +53,7 @@ type InfluxDB struct {
 }
 
 var sampleConfig = `
-  ## The HTTP or UDP URL for your InfluxDB instance.  Each item should be
-  ## of the form:
-  ##   scheme "://" host [ ":" port]
+  ## The full HTTP or UDP URL for your InfluxDB instance.
   ##
   ## Multiple urls can be specified as part of the same cluster,
   ## this means that only ONE of the urls will be written to each interval.