improve: support multiple registry mirrors

cmd/drone-docker/main.go

@@ -53,7 +53,7 @@ func main() {
 		},
 		cli.StringFlag{
 			Name:   "daemon.mirror",
-			Usage:  "docker daemon registry mirror",
+			Usage:  "docker daemon registry mirror. Multiple mirrors are separated by commas ','",
 			EnvVar: "PLUGIN_MIRROR,DOCKER_PLUGIN_MIRROR",
 		},
 		cli.StringFlag{

daemon_test.go

@@ -0,0 +1,74 @@
+package docker
+
+import (
+	"os/exec"
+	"reflect"
+	"testing"
+)
+
+func TestCommandStartDaemon(t *testing.T) {
+	tcs := []struct {
+		name   string
+		daemon Daemon
+		want   *exec.Cmd
+	}{
+		{
+			name: "multi mirrors",
+			daemon: Daemon{
+				StoragePath: "/var/lib/docker",
+				Mirror:      "https://a.com,https://b.com,https://c.com",
+			},
+			want: exec.Command(
+				dockerdExe,
+				"--data-root",
+				"/var/lib/docker",
+				"--host=unix:///var/run/docker.sock",
+				"--registry-mirror",
+				"https://a.com",
+				"--registry-mirror",
+				"https://b.com",
+				"--registry-mirror",
+				"https://c.com",
+			),
+		},
+		{
+			name: "single mirrors",
+			daemon: Daemon{
+				StoragePath: "/var/lib/docker",
+				Mirror:      "https://a.com",
+			},
+			want: exec.Command(
+				dockerdExe,
+				"--data-root",
+				"/var/lib/docker",
+				"--host=unix:///var/run/docker.sock",
+				"--registry-mirror",
+				"https://a.com",
+			),
+		},
+		{
+			name: "zero mirrors",
+			daemon: Daemon{
+				StoragePath: "/var/lib/docker",
+			},
+			want: exec.Command(
+				dockerdExe,
+				"--data-root",
+				"/var/lib/docker",
+				"--host=unix:///var/run/docker.sock",
+			),
+		},
+	}
+
+	for _, tc := range tcs {
+		tc := tc
+
+		t.Run(tc.name, func(t *testing.T) {
+			cmd := commandDaemon(tc.daemon)
+
+			if !reflect.DeepEqual(cmd.String(), tc.want.String()) {
+				t.Errorf("Got cmd %v, want %v", cmd, tc.want)
+			}
+		})
+	}
+}

docker.go

@@ -608,7 +608,10 @@ func commandDaemon(daemon Daemon) *exec.Cmd {
 		args = append(args, "--ipv6")
 	}
 	if len(daemon.Mirror) != 0 {
-		args = append(args, "--registry-mirror", daemon.Mirror)
+		mirrors := strings.Split(daemon.Mirror, ",")
+		for _, mirror := range mirrors {
+			args = append(args, "--registry-mirror", mirror)
+		}
 	}
 	if len(daemon.Bip) != 0 {
 		args = append(args, "--bip", daemon.Bip)