feat: add Close method for resource cleanup in graceful shutdown

CHANGELOG.md

@@ -115,6 +115,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (x/staking) [#16068](https://github.com/cosmos/cosmos-sdk/pull/16068) Update simulation to allow non-EOA accounts to stake
 * (store) [#16067](https://github.com/cosmos/cosmos-sdk/pull/16067) Add local snapshots management commands.
 * (server) [#16142](https://github.com/cosmos/cosmos-sdk/pull/16142) Remove JSON Indentation from the GRPC to REST gateway's responses. (Saving bandwidth)
+* (baseapp) [#16193](https://github.com/cosmos/cosmos-sdk/pull/16193) Add `Close` method to `BaseApp` for custom app to cleanup resource in graceful shutdown.
 
 ### State Machine Breaking
 

baseapp/baseapp.go

@@ -1031,3 +1031,8 @@ func NoOpProcessProposal() sdk.ProcessProposalHandler {
 		return abci.ResponseProcessProposal{Status: abci.ResponseProcessProposal_ACCEPT}
 	}
 }
+
+// Close is called in start cmd to gracefully cleanup resources.
+func (app *BaseApp) Close() error {
+	return nil
+}

server/start.go

@@ -2,6 +2,7 @@ package server
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"net"
@@ -260,7 +261,7 @@ func startStandAlone(svrCtx *Context, appCreator types.AppCreator) error {
 		// so we can gracefully stop the ABCI server.
 		<-ctx.Done()
 		svrCtx.Logger.Info("stopping the ABCI server...")
-		return svr.Stop()
+		return errors.Join(svr.Stop(), app.Close())
 	})
 
 	return g.Wait()
@@ -366,6 +367,7 @@ func startInProcess(svrCtx *Context, clientCtx client.Context, appCreator types.
 	defer func() {
 		if tmNode != nil && tmNode.IsRunning() {
 			_ = tmNode.Stop()
+			_ = app.Close()
 		}
 
 		if traceWriterCleanup != nil {

server/types/app.go

@@ -58,6 +58,9 @@ type (
 
 		// Return the snapshot manager
 		SnapshotManager() *snapshots.Manager
+
+		// Close is called in start cmd to gracefully cleanup resources.
+		Close() error
 	}
 
 	// AppCreator is a function that allows us to lazily initialize an