op-program: Specify client program to run as an executable

Removes the env var approach to toggling between the host and client executables.

op-e2e/build_helper.go

+package op_e2e
+
+import (
+	"context"
+	"os"
+	"os/exec"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+// BuildOpProgramClient builds the `op-program` client executable and returns the path to the resulting executable
+func BuildOpProgramClient(t *testing.T) string {
+	t.Log("Building op-program-client")
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Minute)
+	defer cancel()
+	cmd := exec.CommandContext(ctx, "make", "op-program-client")
+	cmd.Dir = "../op-program"
+	cmd.Stdout = os.Stdout // for debugging
+	cmd.Stderr = os.Stderr // for debugging
+	require.NoError(t, cmd.Run(), "Failed to build op-program-client")
+	t.Log("Built op-program-client successfully")
+	return "../op-program/bin/op-program-client"
+}

op-e2e/system_fpp_test.go

@@ -9,11 +9,9 @@ import (
 	"github.com/ethereum-optimism/optimism/op-node/client"
 	"github.com/ethereum-optimism/optimism/op-node/sources"
 	"github.com/ethereum-optimism/optimism/op-node/testlog"
-	oppcl "github.com/ethereum-optimism/optimism/op-program/client"
 	"github.com/ethereum-optimism/optimism/op-program/client/driver"
 	opp "github.com/ethereum-optimism/optimism/op-program/host"
 	oppconf "github.com/ethereum-optimism/optimism/op-program/host/config"
-	oplog "github.com/ethereum-optimism/optimism/op-service/log"
 	"github.com/ethereum/go-ethereum/accounts/abi/bind"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/log"
@@ -21,18 +19,6 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-// bypass the test runnner if running client to execute the fpp directly
-func init() {
-	if !opp.RunningProgramInClient() {
-		return
-	}
-	logger := oplog.NewLogger(oplog.CLIConfig{
-		Level:  "debug",
-		Format: "text",
-	})
-	oppcl.Main(logger)
-}
-
 func TestVerifyL2OutputRoot(t *testing.T) {
 	testVerifyL2OutputRoot(t, false)
 }
@@ -115,7 +101,10 @@ func testVerifyL2OutputRoot(t *testing.T, detached bool) {
 	fppConfig.L1URL = sys.NodeEndpoint("l1")
 	fppConfig.L2URL = sys.NodeEndpoint("sequencer")
 	fppConfig.DataDir = preimageDir
-	fppConfig.Detached = detached
+	if detached {
+		// When running in detached mode we need to compile the client executable since it will be called directly.
+		fppConfig.ExecCmd = BuildOpProgramClient(t)
+	}
 
 	// Check the FPP confirms the expected output
 	t.Log("Running fault proof in fetching mode")

op-program/host/cmd/main.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"os"
 
-	cl "github.com/ethereum-optimism/optimism/op-program/client"
 	"github.com/ethereum-optimism/optimism/op-program/client/driver"
 	"github.com/ethereum-optimism/optimism/op-program/host"
 	"github.com/ethereum-optimism/optimism/op-program/host/config"
@@ -37,11 +36,6 @@ var VersionWithMeta = func() string {
 }()
 
 func main() {
-	if host.RunningProgramInClient() {
-		logger := oplog.NewLogger(oplog.DefaultCLIConfig())
-		cl.Main(logger)
-		panic("Client main should have exited process")
-	}
 	args := os.Args
 	if err := run(args, host.FaultProofProgram); errors.Is(err, driver.ErrClaimNotValid) {
 		log.Crit("Claim is invalid", "err", err)

op-program/host/cmd/main_test.go

@@ -220,22 +220,15 @@ func TestL2BlockNumber(t *testing.T) {
 	})
 }
 
-func TestDetached(t *testing.T) {
-	t.Run("DefaultFalse", func(t *testing.T) {
+func TestExec(t *testing.T) {
+	t.Run("DefaultEmpty", func(t *testing.T) {
 		cfg := configForArgs(t, addRequiredArgs())
-		require.False(t, cfg.Detached)
-	})
-	t.Run("Enabled", func(t *testing.T) {
-		cfg := configForArgs(t, addRequiredArgs("--detached"))
-		require.True(t, cfg.Detached)
+		require.Equal(t, "", cfg.ExecCmd)
 	})
-	t.Run("EnabledWithArg", func(t *testing.T) {
-		cfg := configForArgs(t, addRequiredArgs("--detached=true"))
-		require.True(t, cfg.Detached)
-	})
-	t.Run("Disabled", func(t *testing.T) {
-		cfg := configForArgs(t, addRequiredArgs("--detached=false"))
-		require.False(t, cfg.Detached)
+	t.Run("Set", func(t *testing.T) {
+		cmd := "/bin/echo"
+		cfg := configForArgs(t, addRequiredArgs("--exec", cmd))
+		require.Equal(t, cmd, cfg.ExecCmd)
 	})
 }
 

op-program/host/config/config.go

@@ -49,8 +49,9 @@ type Config struct {
 	L2ClaimBlockNumber uint64
 	// L2ChainConfig is the op-geth chain config for the L2 execution engine
 	L2ChainConfig *params.ChainConfig
-	// Detached indicates that the program runs as a separate process
-	Detached bool
+	// ExecCmd specifies the client program to execute in a separate process.
+	// If unset, the fault proof client is run in the same process.
+	ExecCmd string
 }
 
 func (c *Config) Check() error {
@@ -148,7 +149,7 @@ func NewConfigFromCLI(ctx *cli.Context) (*Config, error) {
 		L1URL:              ctx.GlobalString(flags.L1NodeAddr.Name),
 		L1TrustRPC:         ctx.GlobalBool(flags.L1TrustRPC.Name),
 		L1RPCKind:          sources.RPCProviderKind(ctx.GlobalString(flags.L1RPCProviderKind.Name)),
-		Detached:           ctx.GlobalBool(flags.Detached.Name),
+		ExecCmd:            ctx.String(flags.Exec.Name),
 	}, nil
 }
 

op-program/host/flags/flags.go

@@ -81,10 +81,10 @@ var (
 			return &out
 		}(),
 	}
-	Detached = cli.BoolFlag{
-		Name:   "detached",
-		Usage:  "Run the program as a separate process detached from the host",
-		EnvVar: service.PrefixEnvVar(envVarPrefix, "DETACHED"),
+	Exec = cli.StringFlag{
+		Name:   "exec",
+		Usage:  "Run the specified client program as a separate process detached from the host. Default is to run the client program in the host process.",
+		EnvVar: service.PrefixEnvVar(envVarPrefix, "EXEC"),
 	}
 )
 
@@ -106,7 +106,7 @@ var programFlags = []cli.Flag{
 	L1NodeAddr,
 	L1TrustRPC,
 	L1RPCProviderKind,
-	Detached,
+	Exec,
 }
 
 func init() {

op-program/host/host.go

@@ -27,13 +27,6 @@ type L2Source struct {
 	*sources.DebugClient
 }
 
-const opProgramChildEnvName = "OP_PROGRAM_CHILD"
-
-func RunningProgramInClient() bool {
-	value, _ := os.LookupEnv(opProgramChildEnvName)
-	return value == "true"
-}
-
 // FaultProofProgram is the programmatic entry-point for the fault proof program
 func FaultProofProgram(logger log.Logger, cfg *config.Config) error {
 	if err := cfg.Check(); err != nil {
@@ -96,8 +89,8 @@ func FaultProofProgram(logger log.Logger, cfg *config.Config) error {
 	routeHints(logger, hHost, hinter)
 
 	var cmd *exec.Cmd
-	if cfg.Detached {
-		cmd = exec.CommandContext(ctx, os.Args[0])
+	if cfg.ExecCmd != "" {
+		cmd = exec.CommandContext(ctx, cfg.ExecCmd)
 		cmd.ExtraFiles = make([]*os.File, cl.MaxFd-3) // not including stdin, stdout and stderr
 		cmd.ExtraFiles[cl.HClientRFd-3] = hClientRW.Reader()
 		cmd.ExtraFiles[cl.HClientWFd-3] = hClientRW.Writer()
@@ -105,7 +98,6 @@ func FaultProofProgram(logger log.Logger, cfg *config.Config) error {
 		cmd.ExtraFiles[cl.PClientWFd-3] = pClientRW.Writer()
 		cmd.Stdout = os.Stdout // for debugging
 		cmd.Stderr = os.Stderr // for debugging
-		cmd.Env = append(os.Environ(), fmt.Sprintf("%s=true", opProgramChildEnvName))
 
 		err := cmd.Start()
 		if err != nil {