refactor: put GetAdminAPI as a separate function instead of directly coding it

op-batcher/batcher/batch_submitter.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 	_ "net/http/pprof"
 
-	gethrpc "github.com/ethereum/go-ethereum/rpc"
 	"github.com/urfave/cli/v2"
 
 	"github.com/ethereum-optimism/optimism/op-batcher/flags"
@@ -82,10 +81,8 @@ func Main(version string, cliCtx *cli.Context) error {
 	)
 	if cfg.RPCFlag.EnableAdmin {
 		rpcMetrics := opmetrics.NewRPCMetrics(procName, metrics.Namespace)
-		server.AddAPI(gethrpc.API{
-			Namespace: "admin",
-			Service:   rpc.NewAdminAPI(batchSubmitter, rpcMetrics, l),
-		})
+		adminAPI := rpc.NewAdminAPI(batchSubmitter, rpcMetrics, l)
+		server.AddAPI(rpc.GetAdminAPI(adminAPI))
 		l.Info("Admin RPC enabled")
 	}
 	if err := server.Start(); err != nil {

op-batcher/rpc/api.go

@@ -4,6 +4,7 @@ import (
 	"context"
 
 	"github.com/ethereum/go-ethereum/log"
+	gethrpc "github.com/ethereum/go-ethereum/rpc"
 
 	"github.com/ethereum-optimism/optimism/op-service/metrics"
 	"github.com/ethereum-optimism/optimism/op-service/rpc"
@@ -26,6 +27,13 @@ func NewAdminAPI(dr batcherClient, m metrics.RPCMetricer, log log.Logger) *admin
 	}
 }
 
+func GetAdminAPI(api *adminAPI) gethrpc.API {
+	return gethrpc.API{
+		Namespace: "admin",
+		Service:   api,
+	}
+}
+
 func (a *adminAPI) StartBatcher(_ context.Context) error {
 	return a.b.Start()
 }