add golangci-lint linter (#5499)

plugin/clouddns/clouddns.go

@@ -204,7 +204,6 @@ func (h *CloudDNS) updateZones(ctx context.Context) error {
 				(*z[i]).z = newZ
 				h.zMu.Unlock()
 			}
-
 		}(zName, z)
 	}
 	// Collect errors (if any). This will also sync on all zones updates

plugin/clouddns/clouddns_test.go

@@ -152,7 +152,6 @@ func TestCloudDNS(t *testing.T) {
 
 			m.Authoritative = true
 			rcode = dns.RcodeSuccess
-
 		}
 
 		m.SetRcode(r, rcode)

plugin/clouddns/setup.go

@@ -81,16 +81,19 @@ func setup(c *caddy.Controller) error {
 		ctx, cancel := context.WithCancel(context.Background())
 		client, err := f(ctx, opt)
 		if err != nil {
+			cancel()
 			return err
 		}
 
 		h, err := New(ctx, client, keys, up)
 		if err != nil {
+			cancel()
 			return plugin.Error("clouddns", c.Errf("failed to create plugin: %v", err))
 		}
 		h.Fall = fall
 
 		if err := h.Run(ctx); err != nil {
+			cancel()
 			return plugin.Error("clouddns", c.Errf("failed to initialize plugin: %v", err))
 		}