Respect path prefix in influx output uri (#3224)

plugins/outputs/influxdb/client/http.go

@@ -10,6 +10,7 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/url"
+	"path"
 	"time"
 )
 
@@ -305,8 +306,11 @@ 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 {
@@ -314,6 +318,9 @@ 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

@@ -373,3 +373,39 @@ 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.Write([]byte("cpu value=99\n"))
+	assert.NoError(t, err)
+	_, err = client.WriteStream(bytes.NewReader([]byte("cpu value=99\n")), 13)
+	assert.NoError(t, err)
+}