Fix: it's ok to stop the connection.

pkg/acquisition/modules/loki/loki.go

@@ -12,6 +12,7 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
+	"net"
 	"net/http"
 	"net/url"
 	"time"
@@ -346,6 +347,13 @@ func (l *LokiSource) StreamingAcquisition(out chan types.Event, t *tomb.Tomb) er
 			}()
 			c, res, err := l.dialer.DialContext(ctx, l.lokiWebsocket, l.header)
 			if err != nil {
+				if oerr, ok := err.(*net.OpError); ok && oerr.Err.Error() == "operation was canceled" {
+					// it's ok, the websocket connection is closed by the client, triggered by the tomb, lets stop
+					return nil
+				}
+				if res == nil { // no body, it's a network error, not a HTTP error
+					return errors.Wrap(err, "loki OneShotAcquisition error before HTTP stack")
+				}
 				buf, err2 := ioutil.ReadAll(res.Body)
 				if err2 == nil {
 					return fmt.Errorf("loki websocket (%s) error %v : %s", l.lokiWebsocket, err, string(buf))