Remote write: read first line of response and include it in the error.

storage/remote/client.go

@@ -14,6 +14,7 @@
 package remote
 
 import (
+	"bufio"
 	"bytes"
 	"fmt"
 	"io/ioutil"
@@ -117,7 +118,12 @@ func (c *Client) Store(samples model.Samples) error {
 	defer httpResp.Body.Close()
 
 	if httpResp.StatusCode/100 != 2 {
-		err = fmt.Errorf("server returned HTTP status %s", httpResp.Status)
+		scanner := bufio.NewScanner(httpResp.Body)
+		line := ""
+		if scanner.Scan() {
+			line = scanner.Text()
+		}
+		err = fmt.Errorf("server returned HTTP status %s: %s", httpResp.Status, line)
 	}
 	if httpResp.StatusCode/100 == 5 {
 		return recoverableError{err}

storage/remote/client_test.go

@@ -37,15 +37,15 @@ func TestStoreHTTPErrorHandling(t *testing.T) {
 		},
 		{
 			code: 300,
-			err:  fmt.Errorf("server returned HTTP status 300 Multiple Choices"),
+			err:  fmt.Errorf("server returned HTTP status 300 Multiple Choices: test error"),
 		},
 		{
 			code: 404,
-			err:  fmt.Errorf("server returned HTTP status 404 Not Found"),
+			err:  fmt.Errorf("server returned HTTP status 404 Not Found: test error"),
 		},
 		{
 			code: 500,
-			err:  recoverableError{fmt.Errorf("server returned HTTP status 500 Internal Server Error")},
+			err:  recoverableError{fmt.Errorf("server returned HTTP status 500 Internal Server Error: test error")},
 		},
 	}
 
@@ -68,7 +68,7 @@ func TestStoreHTTPErrorHandling(t *testing.T) {
 
 		err = c.Store(nil)
 		if !reflect.DeepEqual(err, test.err) {
-			t.Fatalf("%d. Unexpected error; want %v, got %v", i, test.err, err)
+			t.Errorf("%d. Unexpected error; want %v, got %v", i, test.err, err)
 		}
 
 		server.Close()