op-node/flags: Add easy way to deprecate flags

This adds a deprecated flags section to warn users that the flag will be removed
in a future version of the software. I had to modify the P2P Flags structure to
make it work nicely.

I also added a test to ensure that deprecated flags are hidden & that all flags
have at least one env var.

op-node/cmd/main.go

@@ -76,6 +76,7 @@ func RollupNodeMain(ctx *cli.Context, closeApp context.CancelCauseFunc) (cliapp.
 	log := oplog.NewLogger(oplog.AppOut(ctx), logCfg)
 	oplog.SetGlobalLogHandler(log.GetHandler())
 	opservice.ValidateEnvVars(flags.EnvVarPrefix, flags.Flags, log)
+	opservice.WarnOnDeprecatedFlags(ctx, flags.DeprecatedFlags, log)
 	m := metrics.NewMetrics("default")
 
 	cfg, err := opnode.NewConfig(ctx, log)

op-node/flags/flags.go

@@ -35,6 +35,13 @@ var (
 		Usage:   "Address of L2 Engine JSON-RPC endpoints to use (engine and eth namespace required)",
 		EnvVars: prefixEnvVars("L2_ENGINE_RPC"),
 	}
+	L2EngineJWTSecret = &cli.StringFlag{
+		Name:        "l2.jwt-secret",
+		Usage:       "Path to JWT secret key. Keys are 32 bytes, hex encoded in a file. A new key will be generated if the file is empty.",
+		EnvVars:     prefixEnvVars("L2_ENGINE_AUTH"),
+		Value:       "",
+		Destination: new(string),
+	}
 	RollupConfig = &cli.StringFlag{
 		Name:    "rollup.config",
 		Usage:   "Rollup chain parameters",
@@ -97,7 +104,6 @@ var (
 		Name:    "l1.rethdb",
 		Usage:   "The L1 RethDB path, used to fetch receipts for L1 blocks. Only applicable when using the `reth_db` RPC kind with `l1.rpckind`.",
 		EnvVars: prefixEnvVars("L1_RETHDB"),
-		Required: false,
 		Hidden:  true,
 	}
 	L1RPCMaxConcurrency = &cli.IntFlag{
@@ -124,19 +130,10 @@ var (
 		EnvVars: prefixEnvVars("L1_HTTP_POLL_INTERVAL"),
 		Value:   time.Second * 12,
 	}
-	L2EngineJWTSecret = &cli.StringFlag{
-		Name:        "l2.jwt-secret",
-		Usage:       "Path to JWT secret key. Keys are 32 bytes, hex encoded in a file. A new key will be generated if left empty.",
-		EnvVars:     prefixEnvVars("L2_ENGINE_AUTH"),
-		Required:    false,
-		Value:       "",
-		Destination: new(string),
-	}
 	VerifierL1Confs = &cli.Uint64Flag{
 		Name:    "verifier.l1-confs",
 		Usage:   "Number of L1 blocks to keep distance from the L1 head before deriving L2 data from. Reorgs are supported, but may be slow to perform.",
 		EnvVars: prefixEnvVars("VERIFIER_L1_CONFS"),
-		Required: false,
 		Value:   0,
 	}
 	SequencerEnabledFlag = &cli.BoolFlag{
@@ -153,28 +150,24 @@ var (
 		Name:    "sequencer.max-safe-lag",
 		Usage:   "Maximum number of L2 blocks for restricting the distance between L2 safe and unsafe. Disabled if 0.",
 		EnvVars: prefixEnvVars("SEQUENCER_MAX_SAFE_LAG"),
-		Required: false,
 		Value:   0,
 	}
 	SequencerL1Confs = &cli.Uint64Flag{
 		Name:    "sequencer.l1-confs",
 		Usage:   "Number of L1 blocks to keep distance from the L1 head as a sequencer for picking an L1 origin.",
 		EnvVars: prefixEnvVars("SEQUENCER_L1_CONFS"),
-		Required: false,
 		Value:   4,
 	}
 	L1EpochPollIntervalFlag = &cli.DurationFlag{
 		Name:    "l1.epoch-poll-interval",
 		Usage:   "Poll interval for retrieving new L1 epoch updates such as safe and finalized block changes. Disabled if 0 or negative.",
 		EnvVars: prefixEnvVars("L1_EPOCH_POLL_INTERVAL"),
-		Required: false,
 		Value:   time.Second * 12 * 32,
 	}
 	RuntimeConfigReloadIntervalFlag = &cli.DurationFlag{
 		Name:    "l1.runtime-config-reload-interval",
 		Usage:   "Poll interval for reloading the runtime config, useful when config events are not being picked up. Disabled if 0 or negative.",
 		EnvVars: prefixEnvVars("L1_RUNTIME_CONFIG_RELOAD_INTERVAL"),
-		Required: false,
 		Value:   time.Minute * 10,
 	}
 	MetricsEnabledFlag = &cli.BoolFlag{
@@ -236,38 +229,14 @@ var (
 		Name:    "l2.backup-unsafe-sync-rpc",
 		Usage:   "Set the backup L2 unsafe sync RPC endpoint.",
 		EnvVars: prefixEnvVars("L2_BACKUP_UNSAFE_SYNC_RPC"),
-		Required: false,
 	}
 	BackupL2UnsafeSyncRPCTrustRPC = &cli.StringFlag{
 		Name: "l2.backup-unsafe-sync-rpc.trustrpc",
 		Usage: "Like l1.trustrpc, configure if response data from the RPC needs to be verified, e.g. blockhash computation." +
 			"This does not include checks if the blockhash is part of the canonical chain.",
 		EnvVars: prefixEnvVars("L2_BACKUP_UNSAFE_SYNC_RPC_TRUST_RPC"),
-		Required: false,
-	}
-	// Delete this flag at a later date.
-	L2EngineSyncEnabled = &cli.BoolFlag{
-		Name:     "l2.engine-sync",
-		Usage:    "WARNING: Deprecated. Use --syncmode=execution-layer instead",
-		EnvVars:  prefixEnvVars("L2_ENGINE_SYNC_ENABLED"),
-		Required: false,
-		Value:    false,
-		Hidden:   true,
-	}
-	SkipSyncStartCheck = &cli.BoolFlag{
-		Name: "l2.skip-sync-start-check",
-		Usage: "Skip sanity check of consistency of L1 origins of the unsafe L2 blocks when determining the sync-starting point. " +
-			"This defers the L1-origin verification, and is recommended to use in when utilizing l2.engine-sync",
-		EnvVars:  prefixEnvVars("L2_SKIP_SYNC_START_CHECK"),
-		Required: false,
-		Value:    false,
-	}
-	BetaExtraNetworks = &cli.BoolFlag{
-		Name:    "beta.extra-networks",
-		Usage:   "Legacy flag, ignored, all superchain-registry networks are enabled by default.",
-		EnvVars: prefixEnvVars("BETA_EXTRA_NETWORKS"),
-		Hidden:  true, // hidden, this is deprecated, the flag is not used anymore.
 	}
+
 	RollupHalt = &cli.StringFlag{
 		Name:    "rollup.halt",
 		Usage:   "Opt-in option to halt on incompatible protocol version requirements of the given level (major/minor/patch/none), as signaled onchain in L1",
@@ -290,11 +259,34 @@ var (
 		EnvVars: prefixEnvVars("OVERRIDE_DELTA"),
 		Hidden:  false,
 	}
+	/* Deprecated Flags */
+	L2EngineSyncEnabled = &cli.BoolFlag{
+		Name:    "l2.engine-sync",
+		Usage:   "WARNING: Deprecated. Use --syncmode=execution-layer instead",
+		EnvVars: prefixEnvVars("L2_ENGINE_SYNC_ENABLED"),
+		Value:   false,
+		Hidden:  true,
+	}
+	SkipSyncStartCheck = &cli.BoolFlag{
+		Name: "l2.skip-sync-start-check",
+		Usage: "Skip sanity check of consistency of L1 origins of the unsafe L2 blocks when determining the sync-starting point. " +
+			"This defers the L1-origin verification, and is recommended to use in when utilizing l2.engine-sync",
+		EnvVars: prefixEnvVars("L2_SKIP_SYNC_START_CHECK"),
+		Value:   false,
+		Hidden:  true,
+	}
+	BetaExtraNetworks = &cli.BoolFlag{
+		Name:    "beta.extra-networks",
+		Usage:   "Legacy flag, ignored, all superchain-registry networks are enabled by default.",
+		EnvVars: prefixEnvVars("BETA_EXTRA_NETWORKS"),
+		Hidden:  true, // hidden, this is deprecated, the flag is not used anymore.
+	}
 )
 
 var requiredFlags = []cli.Flag{
 	L1NodeAddr,
 	L2EngineAddr,
+	L2EngineJWTSecret,
 }
 
 var optionalFlags = []cli.Flag{
@@ -309,7 +301,6 @@ var optionalFlags = []cli.Flag{
 	L1RPCMaxBatchSize,
 	L1RPCMaxConcurrency,
 	L1HTTPPollInterval,
-	L2EngineJWTSecret,
 	VerifierL1Confs,
 	SequencerEnabledFlag,
 	SequencerStoppedFlag,
@@ -331,30 +322,56 @@ var optionalFlags = []cli.Flag{
 	HeartbeatURLFlag,
 	BackupL2UnsafeSyncRPC,
 	BackupL2UnsafeSyncRPCTrustRPC,
-	L2EngineSyncEnabled,
-	SkipSyncStartCheck,
-	BetaExtraNetworks,
 	RollupHalt,
 	RollupLoadProtocolVersions,
-	CanyonOverrideFlag,
 	L1RethDBPath,
+	CanyonOverrideFlag,
 	DeltaOverrideFlag,
 }
 
+var DeprecatedFlags = []cli.Flag{
+	L2EngineSyncEnabled,
+	SkipSyncStartCheck,
+	BetaExtraNetworks,
+	// Deprecated P2P Flags are added at the init step
+}
+
 // Flags contains the list of configuration options available to the binary.
 var Flags []cli.Flag
 
 func init() {
+	DeprecatedFlags = append(DeprecatedFlags, deprecatedP2PFlags(EnvVarPrefix)...)
 	optionalFlags = append(optionalFlags, P2PFlags(EnvVarPrefix)...)
 	optionalFlags = append(optionalFlags, oplog.CLIFlags(EnvVarPrefix)...)
+	optionalFlags = append(optionalFlags, DeprecatedFlags...)
 	Flags = append(requiredFlags, optionalFlags...)
 }
 
+// This checks flags that are exclusive & required. Specifically for each
+// set of flags, exactly one flag must be set.
+var requiredXorFlags = [][]string{
+	{
+		RollupConfig.Name,
+		Network.Name,
+	},
+}
+
 func CheckRequired(ctx *cli.Context) error {
 	for _, f := range requiredFlags {
 		if !ctx.IsSet(f.Names()[0]) {
 			return fmt.Errorf("flag %s is required", f.Names()[0])
 		}
 	}
+	for _, flagNames := range requiredXorFlags {
+		setCount := 0
+		for _, f := range flagNames {
+			if ctx.IsSet(f) {
+				setCount += 1
+			}
+		}
+		if setCount != 1 {
+			return fmt.Errorf("exactly one of the flags %v is required", flagNames)
+		}
+	}
 	return nil
 }

op-node/flags/flags_test.go

@@ -4,7 +4,6 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"github.com/urfave/cli/v2"
 )
@@ -44,10 +43,45 @@ func TestBetaFlags(t *testing.T) {
 		name := flag.Names()[0]
 		envName := envFlag.GetEnvVars()[0]
 		if strings.HasPrefix(name, "beta.") {
-			assert.Contains(t, envName, "BETA_", "%q flag must contain BETA in env var to match \"beta.\" flag name", name)
+			require.Contains(t, envName, "BETA_", "%q flag must contain BETA in env var to match \"beta.\" flag name", name)
 		}
 		if strings.Contains(envName, "BETA_") {
-			assert.True(t, strings.HasPrefix(name, "beta."), "%q flag must start with \"beta.\" in flag name to match \"BETA_\" env var", name)
+			require.True(t, strings.HasPrefix(name, "beta."), "%q flag must start with \"beta.\" in flag name to match \"BETA_\" env var", name)
 		}
 	}
 }
+
+func TestDeprecatedFlagsAreHidden(t *testing.T) {
+	for _, flag := range DeprecatedFlags {
+		flag := flag
+		flagName := flag.Names()[0]
+
+		t.Run(flagName, func(t *testing.T) {
+
+			visibleFlag, ok := flag.(interface {
+				IsVisible() bool
+			})
+			require.True(t, ok, "Need to case the flag to the correct format")
+			require.False(t, visibleFlag.IsVisible())
+		})
+	}
+}
+
+func TestHasEnvVar(t *testing.T) {
+	for _, flag := range Flags {
+		flag := flag
+		flagName := flag.Names()[0]
+
+		t.Run(flagName, func(t *testing.T) {
+			if flagName == PeerScoringName || flagName == PeerScoreBandsName || flagName == TopicScoringName {
+				t.Skipf("Skipping flag %v which is known to have no env vars", flagName)
+			}
+			envFlagGetter, ok := flag.(interface {
+				GetEnvVars() []string
+			})
+			envFlags := envFlagGetter.GetEnvVars()
+			require.True(t, ok, "must be able to cast the flag to an EnvVar interface")
+			require.Equal(t, 1, len(envFlags), "flags should have exactly one env var")
+		})
+	}
+}

op-node/flags/p2p_flags.go

@@ -55,6 +55,30 @@ var (
 	SyncReqRespName        = "p2p.sync.req-resp"
 )
 
+func deprecatedP2PFlags(envPrefix string) []cli.Flag {
+	return []cli.Flag{
+		&cli.StringFlag{
+			Name:     PeerScoringName,
+			Usage:    fmt.Sprintf("Deprecated: Use %v instead", ScoringName),
+			Required: false,
+			Hidden:   true,
+		},
+		&cli.StringFlag{
+			Name:     PeerScoreBandsName,
+			Usage:    "Deprecated. This option is ignored and is only present for backwards compatibility.",
+			Required: false,
+			Value:    "",
+			Hidden:   true,
+		},
+		&cli.StringFlag{
+			Name:     TopicScoringName,
+			Usage:    fmt.Sprintf("Deprecated: Use %v instead", ScoringName),
+			Required: false,
+			Hidden:   true,
+		},
+	}
+}
+
 // None of these flags are strictly required.
 // Some are hidden if they are too technical, or not recommended.
 func P2PFlags(envPrefix string) []cli.Flag {
@@ -78,19 +102,6 @@ func P2PFlags(envPrefix string) []cli.Flag {
 			Value:    "light",
 			EnvVars:  p2pEnv(envPrefix, "PEER_SCORING"),
 		},
-		&cli.StringFlag{
-			Name:     PeerScoringName,
-			Usage:    fmt.Sprintf("Deprecated: Use %v instead", ScoringName),
-			Required: false,
-			Hidden:   true,
-		},
-		&cli.StringFlag{
-			Name:     PeerScoreBandsName,
-			Usage:    "Deprecated. This option is ignored and is only present for backwards compatibility.",
-			Required: false,
-			Value:    "",
-			Hidden:   true,
-		},
 		&cli.BoolFlag{
 			// Banning Flag - whether or not we want to act on the scoring
 			Name:     BanningName,
@@ -113,12 +124,6 @@ func P2PFlags(envPrefix string) []cli.Flag {
 			Value:    1 * time.Hour,
 			EnvVars:  p2pEnv(envPrefix, "PEER_BANNING_DURATION"),
 		},
-		&cli.StringFlag{
-			Name:     TopicScoringName,
-			Usage:    fmt.Sprintf("Deprecated: Use %v instead", ScoringName),
-			Required: false,
-			Hidden:   true,
-		},
 		&cli.StringFlag{
 			Name: P2PPrivPathName,
 			Usage: "Read the hex-encoded 32-byte private key for the peer ID from this txt file. Created if not already exists." +

op-service/util.go

@@ -62,6 +62,14 @@ func validateEnvVars(prefix string, providedEnvVars []string, definedEnvVars map
 	return out
 }
 
+func WarnOnDeprecatedFlags(ctx *cli.Context, deprecatedFlags []cli.Flag, log log.Logger) {
+	for _, flag := range deprecatedFlags {
+		if ctx.IsSet(flag.Names()[0]) {
+			log.Warn("Found a deprecated flag which will be removed in a future version", "flag_name", flag.Names()[0])
+		}
+	}
+}
+
 // ParseAddress parses an ETH address from a hex string. This method will fail if
 // the address is not a valid hexadecimal address.
 func ParseAddress(address string) (common.Address, error) {