refactor: improvements on rest v2 server (#22292)

(cherry picked from commit 20dd65b)

# Conflicts:
#	server/v2/api/rest/server.go

scripts/init-simapp-v2.sh

@@ -9,7 +9,7 @@ if [ -d "$SIMD_HOME" ]; then rm -rv $SIMD_HOME; fi
 $SIMD_BIN config set client chain-id simapp-v2-chain
 $SIMD_BIN config set client keyring-backend test
 $SIMD_BIN config set client keyring-default-keyname alice
-$SIMD_BIN config set app api.enable true
+$SIMD_BIN config set app rest.enable true
 $SIMD_BIN keys add alice --indiscreet
 $SIMD_BIN keys add bob --indiscreet
 $SIMD_BIN init simapp-v2-node --chain-id simapp-v2-chain

server/v2/api/rest/server.go

@@ -0,0 +1,96 @@
+package rest
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+
+	"cosmossdk.io/core/transaction"
+	"cosmossdk.io/log"
+	serverv2 "cosmossdk.io/server/v2"
+)
+
+const (
+	ServerName = "rest"
+)
+
+type Server[T transaction.Tx] struct {
+	logger log.Logger
+	router *http.ServeMux
+
+	httpServer *http.Server
+	config     *Config
+	cfgOptions []CfgOption
+}
+
+func New[T transaction.Tx](cfgOptions ...CfgOption) *Server[T] {
+	return &Server[T]{
+		cfgOptions: cfgOptions,
+	}
+}
+
+func (s *Server[T]) Name() string {
+	return ServerName
+}
+
+func (s *Server[T]) Init(appI serverv2.AppI[T], cfg map[string]any, logger log.Logger) error {
+	s.logger = logger.With(log.ModuleKey, s.Name())
+
+	serverCfg := s.Config().(*Config)
+	if len(cfg) > 0 {
+		if err := serverv2.UnmarshalSubConfig(cfg, s.Name(), &serverCfg); err != nil {
+			return fmt.Errorf("failed to unmarshal config: %w", err)
+		}
+	}
+
+	s.router = http.NewServeMux()
+	s.router.Handle("/", NewDefaultHandler(appI.GetAppManager()))
+	s.config = serverCfg
+
+	return nil
+}
+
+func (s *Server[T]) Start(ctx context.Context) error {
+	if !s.config.Enable {
+		s.logger.Info(fmt.Sprintf("%s server is disabled via config", s.Name()))
+		return nil
+	}
+
+	s.httpServer = &http.Server{
+		Addr:    s.config.Address,
+		Handler: s.router,
+	}
+
+	s.logger.Info("starting HTTP server", "address", s.config.Address)
+	if err := s.httpServer.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
+		s.logger.Error("failed to start HTTP server", "error", err)
+		return err
+	}
+
+	return nil
+}
+
+func (s *Server[T]) Stop(ctx context.Context) error {
+	if !s.config.Enable {
+		return nil
+	}
+
+	s.logger.Info("stopping HTTP server")
+
+	return s.httpServer.Shutdown(ctx)
+}
+
+func (s *Server[T]) Config() any {
+	if s.config == nil || s.config.Address == "" {
+		cfg := DefaultConfig()
+
+		for _, opt := range s.cfgOptions {
+			opt(cfg)
+		}
+
+		return cfg
+	}
+
+	return s.config
+}

tools/confix/data/v2-app.toml

@@ -33,6 +33,12 @@ max-recv-msg-size = 10485760
 # The default value is math.MaxInt32.
 max-send-msg-size = 2147483647
 
+[rest]
+# Enable defines if the REST server should be enabled.
+enable = true
+# Address defines the REST server address to bind to.
+address = 'localhost:8080'
+
 [server]
 # minimum-gas-prices defines the price which a validator is willing to accept for processing a transaction. A transaction's fees must meet the minimum of any denomination specified in this config (e.g. 0.25token1;0.0001token2).
 minimum-gas-prices = '0stake'