add support for --since in journalctl DSN (#917)

pkg/acquisition/modules/journalctl/journalctl.go

@@ -215,6 +215,8 @@ func (j *JournalCtlSource) ConfigureByDSN(dsn string, labelType string, logger *
 				return errors.Wrapf(err, "unknown level %s", value[0])
 			}
 			j.logger.Logger.SetLevel(lvl)
+		case "since":
+			j.args = append(j.args, "--since", value[0])
 		default:
 			return fmt.Errorf("unsupported key %s in journalctl DSN", key)
 		}

pkg/acquisition/modules/journalctl/journalctl_test.go

@@ -82,6 +82,10 @@ func TestConfigureDSN(t *testing.T) {
 			dsn:         "journalctl://filters=_UID=1000&log_level=foobar",
 			expectedErr: "unknown level foobar: not a valid logrus Level:",
 		},
+		{
+			dsn:         "journalctl://filters=_UID=1000&log_level=warn&since=yesterday",
+			expectedErr: "",
+		},
 	}
 	subLogger := log.WithFields(log.Fields{
 		"type": "journalctl",