doc: add the document to introduce the config-nacos

content/en/docs/kitex/Tutorials/service-governance/config-center/nacos.md

@@ -0,0 +1,365 @@
+---
+title: "Nacos"
+linkTitle: "Nacos"
+date: 2023-12-14
+weight: 4
+keywords: ["ConfigCenter Extension","Nacos"]
+description: "Use Nacos as Kitex’s service governance configuration center"
+---
+
+### Install
+`go get github.com/kitex-contrib/config-nacos`
+
+### Suite
+The configuration center adapter of Nacos.
+
+
+#### Server
+
+```go
+type NacosServerSuite struct {
+	nacosClient nacos.Client
+	service     string  // server-side service name
+	opts        utils.Options
+}
+```
+
+Function Signature:
+
+`func NewSuite(service string, cli nacos.Client, opts ...utils.Option) *NacosServerSuite `
+
+Sample:
+
+```go
+package main
+
+import (
+	"context"
+	"log"
+
+	"github.com/cloudwego/kitex-examples/kitex_gen/api"
+	"github.com/cloudwego/kitex-examples/kitex_gen/api/echo"
+	"github.com/cloudwego/kitex/pkg/klog"
+	"github.com/cloudwego/kitex/pkg/rpcinfo"
+	"github.com/cloudwego/kitex/server"
+	"github.com/kitex-contrib/config-nacos/nacos"
+	nacosserver "github.com/kitex-contrib/config-nacos/server"
+)
+
+var _ api.Echo = &EchoImpl{}
+
+// EchoImpl implements the last service interface defined in the IDL.
+type EchoImpl struct{}
+
+// Echo implements the Echo interface.
+func (s *EchoImpl) Echo(ctx context.Context, req *api.Request) (resp *api.Response, err error) {
+	klog.Info("echo called")
+	return &api.Response{Message: req.Message}, nil
+}
+
+func main() {
+	klog.SetLevel(klog.LevelDebug)
+	nacosClient, err := nacos.NewClient(nacos.Options{})
+	if err != nil {
+		panic(err)
+	}
+	serviceName := "ServiceName"  // your server-side service name
+	svr := echo.NewServer(
+		new(EchoImpl),
+		server.WithServerBasicInfo(&rpcinfo.EndpointBasicInfo{ServiceName: serviceName}),
+		server.WithSuite(nacosserver.NewSuite(serviceName, nacosClient)),
+	)
+	if err := svr.Run(); err != nil {
+		log.Println("server stopped with error:", err)
+	} else {
+		log.Println("server stopped")
+	}
+}
+```
+
+#### Client
+
+```go
+type NacosClientSuite struct {
+	nacosClient nacos.Client
+	service     string
+	client      string
+	opts        utils.Options
+}
+```
+
+Function Signature:
+
+`func NewSuite(service, client string, cli nacos.Client, opts ...utils.Option) *NacosClientSuite `
+
+Sample:
+
+```go
+package main
+
+import (
+	"context"
+	"log"
+
+	"github.com/cloudwego/kitex-examples/kitex_gen/api"
+	"github.com/cloudwego/kitex-examples/kitex_gen/api/echo"
+	"github.com/cloudwego/kitex/client"
+	"github.com/cloudwego/kitex/pkg/klog"
+	nacosclient "github.com/kitex-contrib/config-nacos/client"
+	"github.com/kitex-contrib/config-nacos/nacos"
+	"github.com/nacos-group/nacos-sdk-go/vo"
+)
+
+type configLog struct{}
+
+func (cl *configLog) Apply(opt *utils.Options) {
+	fn := func(cp *vo.ConfigParam) {
+		klog.Infof("nacos config %v", cp)
+	}
+	opt.NacosCustomFunctions = append(opt.NacosCustomFunctions, fn)
+}
+
+func main() {
+	klog.SetLevel(klog.LevelDebug)
+
+	nacosClient, err := nacos.NewClient(nacos.Options{})
+	if err != nil {
+		panic(err)
+	}
+
+	cl := &configLog{}
+	serviceName := "ServiceName"  // your server-side service name
+	clientName := "ClientName"    // your client-side service name
+	client, err := echo.NewClient(
+		serviceName,
+		client.WithHostPorts("0.0.0.0:8888"),
+		client.WithSuite(nacosclient.NewSuite(serviceName, clientName, nacosClient, cl)),
+	)
+	if err != nil {
+		log.Fatal(err)
+	}
+	for {
+		req := &api.Request{Message: "my request"}
+		resp, err := client.Echo(context.Background(), req)
+		if err != nil {
+			klog.Errorf("take request error: %v", err)
+		} else {
+			klog.Infof("receive response %v", resp)
+		}
+	}
+}
+```
+
+#### SetParser
+
+Set a custom parser for deserializing configuration, support json yaml default. User could extend it by self.
+
+Function Signature:
+
+`func SetParser(parser ConfigParser)`
+
+```go
+// ConfigParser the parser for nacos config.
+type ConfigParser interface {
+	Decode(kind vo.ConfigType, data string, config interface{}) error
+}
+```
+
+Sample:
+
+Extend parsing XML types.
+```go
+package main
+
+import (
+    "encoding/xml"
+
+    "sigs.k8s.io/yaml"
+    "github.com/kitex-contrib/config-nacos/nacos"
+)
+
+type parser struct{}
+
+// Decode decodes the data to struct in specified format.
+func (p *parser) Decode(kind vo.ConfigType, data string, config interface{}) error {
+	switch kind {
+	case vo.YAML, vo.JSON:
+		// since YAML is a superset of JSON, it can parse JSON using a YAML parser
+		return yaml.Unmarshal([]byte(data), config)
+	case vo.XML:
+		return xml.Unmarshal([]byte(data), config)
+	default:
+		return fmt.Errorf("unsupported config data type %s", kind)
+	}
+}
+
+
+func main() {
+    client, err := nacos.NewClient(etcd.Options{})
+    if err!=nil {
+        panic(err)
+    }
+    client.SetParser(&parser{})
+}
+```
+
+### Nacos Configuration
+
+The client is initialized according to the parameters of `Options` and connects to the nacos server. After the connection is established, the suite subscribes the appropriate configuration based on `Group`, `ServerDataIDFormat` and `ClientDataIDFormat` to updates its own policy dynamically. See the `Options` variables below for specific parameters.
+
+The configuration format supports `json` and `yaml`. You can use the [SetParser](https://github.com/kitex-contrib/config-nacos/blob/eb006978517678dd75a81513142d3faed6a66f8d/nacos/nacos.go#L68) function to customise the format parsing method, and the `CustomFunction` function to customise the format of the subscription function during `NewSuite`.
+####
+
+#### CustomFunction
+
+Provide the mechanism to custom the nacos parameter `vo.ConfigParam`. 
+
+#### Options Variable
+
+| Variable Name | Default Value | Introduction |
+| ------------------------- | ---------------------------------- | --------------------------------- |
+| Address               | 127.0.0.1                          | Nacos server address, may use the environment of `serverAddr` |
+| Port               | 8848                               | Nacos server port, may use the environment of `serverPort` |
+| NamespaceID                 |                                    | The namespaceID of Nacos, may use the environment of `namespace` |
+| ClientDataIDFormat              | {{.ClientServiceName}}.{{.ServerServiceName}}.{{.Category}}  | Use go [template](https://pkg.go.dev/text/template) syntax rendering to generate the appropriate ID, and use `ClientServiceName` `ServiceName` `Category` three metadata that can be customised          |
+| ServerDataIDFormat              | {{.ServerServiceName}}.{{.Category}}  | Use go [template](https://pkg.go.dev/text/template) syntax rendering to generate the appropriate ID, and use `ServiceName` `Category` two metadatas that can be customised          |
+| Group               | DEFAULT_GROUP                      | Use fixed values or dynamic rendering. Usage is the same as configDataId.          |
+
+#### Governance Policy
+> The configDataId and configGroup in the following example use default values, the service name is `ServiceName` and the client name is `ClientName`.
+
+##### Rate Limit Category=limit
+> Currently, current limiting only supports the server side, so ClientServiceName is empty.
+
+[JSON Schema](https://github.com/cloudwego/kitex/blob/develop/pkg/limiter/item_limiter.go#L33)
+
+|Variable|Introduction|
+|----|----|
+|connection_limit| Maximum concurrent connections | 
+|qps_limit| Maximum request number every 100ms | 
+
+Example:
+
+> configDataID: ServiceName.limit
+
+```json
+{
+  "connection_limit": 100,
+  "qps_limit": 2000
+}
+```
+
+Note:
+
+- The granularity of the current limit configuration is server global, regardless of client or method.
+- Not configured or value is 0 means not enabled.
+- connection_limit and qps_limit can be configured independently, e.g. connection_limit = 100, qps_limit = 0
+
+##### Retry Policy Category=retry
+[JSON Schema](https://github.com/cloudwego/kitex/blob/develop/pkg/retry/policy.go#L63)
+
+|Variable|Introduction|
+|----|----|
+|type| 0: failure_policy 1: backup_policy| 
+|failure_policy.backoff_policy| Can only be set one of `fixed` `none` `random` | 
+
+Example：
+
+> configDataId: ClientName.ServiceName.retry
+
+```json
+{
+    "*": {  
+        "enable": true,
+        "type": 0,                 
+        "failure_policy": {
+            "stop_policy": {
+                "max_retry_times": 3,
+                "max_duration_ms": 2000,
+                "cb_policy": {
+                    "error_rate": 0.3
+                }
+            },
+            "backoff_policy": {
+                "backoff_type": "fixed", 
+                "cfg_items": {
+                    "fix_ms": 50
+                }
+            },
+            "retry_same_node": false
+        }
+    },
+    "echo": { 
+        "enable": true,
+        "type": 1,                 
+        "backup_policy": {
+            "retry_delay_ms": 100,
+            "retry_same_node": false,
+            "stop_policy": {
+                "max_retry_times": 2,
+                "max_duration_ms": 300,
+                "cb_policy": {
+                    "error_rate": 0.2
+                }
+            }
+        }
+    }
+}
+```
+Note: retry.Container has built-in support for specifying the default configuration using the `*` wildcard (see the [getRetryer](https://github.com/cloudwego/kitex/blob/v0.5.1/pkg/retry/retryer.go#L240) method for details).
+
+##### RPC Timeout Category=rpc_timeout
+
+[JSON Schema](https://github.com/cloudwego/kitex/blob/develop/pkg/rpctimeout/item_rpc_timeout.go#L42)
+
+Example：
+
+> configDataId: ClientName.ServiceName.rpc_timeout
+
+```json
+{
+  "*": {
+    "conn_timeout_ms": 100,
+    "rpc_timeout_ms": 3000
+  },
+  "echo": {
+    "conn_timeout_ms": 50,
+    "rpc_timeout_ms": 1000
+  }
+}
+```
+Note: The circuit breaker implementation of kitex does not currently support changing the global default configuration (see [initServiceCB](https://github.com/cloudwego/kitex/blob/v0.5.1/pkg/circuitbreak/cbsuite.go#L195) for details).
+
+##### Circuit Break: Category=circuit_break
+
+[JSON Schema](https://github.com/cloudwego/kitex/blob/develop/pkg/circuitbreak/item_circuit_breaker.go#L30)
+
+|Variable|Introduction|
+|----|----|
+|min_sample| Minimum statistical sample number| 
+
+Example：
+
+The echo method uses the following configuration (0.3, 100) and other methods use the global default configuration (0.5, 200)
+
+> configDataId: `ClientName.ServiecName.circuit_break`
+
+```json
+{
+  "echo": {
+    "enable": true,
+    "err_rate": 0.3, 
+    "min_sample": 100 
+  }
+}
+```
+
+### Note
+Do not delete the config in nacos, otherwise the nacos sdk may produce a large warning log.
+
+
+## Compatibility
+This Package use Nacos1.x client. The Nacos2.0 and Nacos1.0 Server are fully compatible with it. [see](https://nacos.io/en-us/docs/v2/upgrading/2.0.0-compatibility.html)
+
+
+