cmd/geth, cmd/utils: log prefunded account/key in ephemeral development mode

cmd/geth/config.go

@@ -36,6 +36,7 @@ import (
 	"github.com/ethereum/go-ethereum/cmd/utils"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/eth/catalyst"
 	"github.com/ethereum/go-ethereum/eth/ethconfig"
 	"github.com/ethereum/go-ethereum/internal/flags"
@@ -180,6 +181,45 @@ func makeConfigNode(ctx *cli.Context) (*node.Node, gethConfig) {
 	return stack, cfg
 }
 
+// constructs the disclaimer text block which will be printed in the logs upon
+// startup when Geth is running in dev mode.
+func constructDevModeBanner(ctx *cli.Context, cfg gethConfig) string {
+	devModeBanner := `You are running Geth in --dev mode. Please note the following:
+
+  1. This mode is only intended for fast, iterative development without assumptions on
+     security or persistence.
+  2. The database is created in memory unless specified otherwise. Therefore, shutting down
+     your computer or losing power will wipe your entire block data and chain state for
+     your dev environment.
+  3. A random, pre-allocated developer account will be available and unlocked as
+     eth.coinbase, which can be used for testing. The random dev account is temporary,
+     stored on a ramdisk, and will be lost if your machine is restarted.
+  4. Mining is enabled by default. However, the client will only seal blocks if transactions
+     are pending in the mempool. The miner's minimum accepted gas price is 1.
+  5. Networking is disabled; there is no listen-address, the maximum number of peers is set
+     to 0, and discovery is disabled.
+`
+	if !ctx.IsSet(utils.DataDirFlag.Name) {
+		devModeBanner += fmt.Sprintf(`
+
+ Running in ephemeral mode.  The following account has been prefunded in the genesis:
+
+       Account
+       ------------------
+       0x%x (10^49 ETH)
+`, cfg.Eth.Miner.PendingFeeRecipient)
+		if cfg.Eth.Miner.PendingFeeRecipient == utils.DeveloperAddr {
+			devModeBanner += fmt.Sprintf(` 
+       Private Key
+       ------------------
+       0x%x
+`, crypto.FromECDSA(utils.DeveloperKey))
+		}
+	}
+
+	return devModeBanner
+}
+
 // makeFullNode loads geth configuration and creates the Ethereum backend.
 func makeFullNode(ctx *cli.Context) *node.Node {
 	stack, cfg := makeConfigNode(ctx)
@@ -239,6 +279,11 @@ func makeFullNode(ctx *cli.Context) *node.Node {
 		}
 		catalyst.RegisterSimulatedBeaconAPIs(stack, simBeacon)
 		stack.RegisterLifecycle(simBeacon)
+
+		banner := constructDevModeBanner(ctx, cfg)
+		for _, line := range strings.Split(banner, "\n") {
+			log.Warn(line)
+		}
 	} else if ctx.IsSet(utils.BeaconApiFlag.Name) {
 		// Start blsync mode.
 		srv := rpc.NewServer()

cmd/geth/main.go

@@ -294,24 +294,6 @@ func prepare(ctx *cli.Context) {
 	case ctx.IsSet(utils.HoodiFlag.Name):
 		log.Info("Starting Geth on Hoodi testnet...")
 
-	case ctx.IsSet(utils.DeveloperFlag.Name):
-		log.Info("Starting Geth in ephemeral dev mode...")
-		log.Warn(`You are running Geth in --dev mode. Please note the following:
-
-  1. This mode is only intended for fast, iterative development without assumptions on
-     security or persistence.
-  2. The database is created in memory unless specified otherwise. Therefore, shutting down
-     your computer or losing power will wipe your entire block data and chain state for
-     your dev environment.
-  3. A random, pre-allocated developer account will be available and unlocked as
-     eth.coinbase, which can be used for testing. The random dev account is temporary,
-     stored on a ramdisk, and will be lost if your machine is restarted.
-  4. Mining is enabled by default. However, the client will only seal blocks if transactions
-     are pending in the mempool. The miner's minimum accepted gas price is 1.
-  5. Networking is disabled; there is no listen-address, the maximum number of peers is set
-     to 0, and discovery is disabled.
-`)
-
 	case !ctx.IsSet(utils.NetworkIdFlag.Name):
 		log.Info("Starting Geth on Ethereum mainnet...")
 	}

cmd/utils/flags.go

@@ -984,6 +984,12 @@ var (
 	}
 )
 
+// default account to prefund when running Geth in dev mode
+var (
+	DeveloperKey, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
+	DeveloperAddr   = crypto.PubkeyToAddress(DeveloperKey.PublicKey)
+)
+
 // MakeDataDir retrieves the currently requested data directory, terminating
 // if none (or the empty string) is specified. If the node is starting a testnet,
 // then a subdirectory of the specified datadir will be used.
@@ -1769,9 +1775,9 @@ func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *ethconfig.Config) {
 		} else if accs := ks.Accounts(); len(accs) > 0 {
 			developer = ks.Accounts()[0]
 		} else {
-			developer, err = ks.NewAccount(passphrase)
+			developer, err = ks.ImportECDSA(DeveloperKey, passphrase)
 			if err != nil {
-				Fatalf("Failed to create developer account: %v", err)
+				Fatalf("Failed to import developer account: %v", err)
 			}
 		}
 		// Make sure the address is configured as fee recipient, otherwise
@@ -1786,14 +1792,18 @@ func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *ethconfig.Config) {
 		}
 		log.Info("Using developer account", "address", developer.Address)
 
-		// Create a new developer genesis block or reuse existing one
+		// configure default developer genesis which will be used unless a
+		// datadir is specified and a chain is preexisting at that location.
 		cfg.Genesis = core.DeveloperGenesisBlock(ctx.Uint64(DeveloperGasLimitFlag.Name), &developer.Address)
+
+		// If a datadir is specified, ensure that any preexisting chain in that location
+		// has a configuration that is compatible with dev mode: it must be merged at genesis.
 		if ctx.IsSet(DataDirFlag.Name) {
 			chaindb := tryMakeReadOnlyDatabase(ctx, stack)
 			if rawdb.ReadCanonicalHash(chaindb, 0) != (common.Hash{}) {
-				cfg.Genesis = nil // fallback to db content
+				// signal fallback to preexisting chain on disk
+				cfg.Genesis = nil
 
-				//validate genesis has PoS enabled in block 0
 				genesis, err := core.ReadGenesis(chaindb)
 				if err != nil {
 					Fatalf("Could not read genesis from database: %v", err)