Add flag for custom slasher database directory (#11890)

* Add slasher database directory flag

* Fix up some beacon chain flag uses

* fmt

Co-authored-by: rauljordan <raul@prysmaticlabs.com>
Co-authored-by: prylabs-bulldozer[bot] <58059840+prylabs-bulldozer[bot]@users.noreply.github.com>

beacon-chain/node/node.go

@@ -448,6 +448,11 @@ func (b *BeaconNode) startSlasherDB(cliCtx *cli.Context) error {
 		return nil
 	}
 	baseDir := cliCtx.String(cmd.DataDirFlag.Name)
+
+	if cliCtx.IsSet(flags.SlasherDirFlag.Name) {
+		baseDir = cliCtx.String(flags.SlasherDirFlag.Name)
+	}
+
 	dbPath := filepath.Join(baseDir, kv.BeaconNodeDbDirName)
 	clearDB := cliCtx.Bool(cmd.ClearDB.Name)
 	forceClearDB := cliCtx.Bool(cmd.ForceClearDB.Name)

cmd/beacon-chain/flags/base.go

@@ -5,6 +5,7 @@ package flags
 import (
 	"strings"
 
+	"github.com/prysmaticlabs/prysm/v3/cmd"
 	"github.com/prysmaticlabs/prysm/v3/config/params"
 	"github.com/urfave/cli/v2"
 )
@@ -246,4 +247,10 @@ var (
 			"WARNING: This flag should be used only if you have a clear understanding that community has decided to override the terminal block hash activation epoch. " +
 			"Incorrect usage will result in your node experience consensus failure.",
 	}
+	// SlasherDirFlag defines a path on disk where the slasher database is stored.
+	SlasherDirFlag = &cli.StringFlag{
+		Name:  "slasher-datadir",
+		Usage: "Directory for the slasher database",
+		Value: cmd.DefaultDataDir(),
+	}
 )

cmd/beacon-chain/main.go

@@ -130,6 +130,7 @@ var appFlags = []cli.Flag{
 	checkpoint.RemoteURL,
 	genesis.StatePath,
 	genesis.BeaconAPIURL,
+	flags.SlasherDirFlag,
 }
 
 func init() {

cmd/beacon-chain/usage.go

@@ -126,6 +126,7 @@ var appHelpFlagGroups = []flagGroup{
 			flags.MaxBuilderEpochMissedSlots,
 			flags.MaxBuilderConsecutiveMissedSlots,
 			flags.EngineEndpointTimeoutSeconds,
+			flags.SlasherDirFlag,
 			checkpoint.BlockPath,
 			checkpoint.StatePath,
 			checkpoint.RemoteURL,