Add custom field in global options (#1098)

* Add custom field in global options

Fix #571

* Add test

Co-authored-by: Allen Zhong <zhongbenli@pingcap.com>
Co-authored-by: Ti Chi Robot <71242396+ti-chi-bot@users.noreply.github.com>

pkg/cluster/spec/spec.go

@@ -68,6 +68,7 @@ type (
 		ResourceControl meta.ResourceControl `yaml:"resource_control,omitempty" validate:"resource_control:editable"`
 		OS              string               `yaml:"os,omitempty" default:"linux"`
 		Arch            string               `yaml:"arch,omitempty" default:"amd64"`
+		Custom          interface{}          `yaml:"custom,omitempty" validate:"custom:ignore"`
 	}
 
 	// MonitoredOptions represents the monitored node configuration

pkg/cluster/spec/spec_test.go

@@ -15,6 +15,7 @@ package spec
 
 import (
 	"bytes"
+	"strings"
 	"testing"
 
 	"github.com/BurntSushi/toml"
@@ -682,3 +683,41 @@ tiflash_servers:
 		c.Check(err, NotNil)
 	}
 }
+
+func (s *metaSuiteTopo) TestYAMLAnchor(c *C) {
+	topo := Specification{}
+	err := yaml.UnmarshalStrict([]byte(`
+global:
+  custom:
+    tidb_spec: &tidb_spec
+      deploy_dir: "test-deploy"
+      log_dir: "test-deploy/log"
+
+tidb_servers:
+  - <<: *tidb_spec
+    host: 172.16.5.138
+    deploy_dir: "fake-deploy"
+`), &topo)
+	c.Assert(err, IsNil)
+	c.Assert(topo.TiDBServers[0].Host, Equals, "172.16.5.138")
+	c.Assert(topo.TiDBServers[0].DeployDir, Equals, "fake-deploy")
+	c.Assert(topo.TiDBServers[0].LogDir, Equals, "test-deploy/log")
+}
+
+func (s *metaSuiteTopo) TestYAMLAnchorWithUndeclared(c *C) {
+	topo := Specification{}
+	err := yaml.UnmarshalStrict([]byte(`
+global:
+  custom:
+    tidb_spec: &tidb_spec
+      deploy_dir: "test-deploy"
+      log_dir: "test-deploy/log"
+      undeclared: "some stuff"
+
+tidb_servers:
+  - <<: *tidb_spec
+    host: 172.16.5.138
+`), &topo)
+	c.Assert(err, NotNil)
+	c.Assert(strings.Contains(err.Error(), "not found"), IsTrue)
+}