feat: support custom mnemonics in in-process testing network (#10922)

## Description

In certain cases, it proves to be beneficial to be able to support user provided mnemonics in the in-process testing network. This essentially allows you to know the validator addresses ahead of time in case you need to do any custom genesis logic (e.g. Gravity Bridge delegation keys).

---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

server/init.go

@@ -14,18 +14,25 @@ func GenerateCoinKey(algo keyring.SignatureAlgo, cdc codec.Codec) (sdk.AccAddres
 	// generate a private key, with recovery phrase
 	k, secret, err := keyring.NewInMemory(cdc).NewMnemonic("name", keyring.English, sdk.GetConfig().GetFullBIP44Path(), keyring.DefaultBIP39Passphrase, algo)
 	if err != nil {
-		return sdk.AccAddress([]byte{}), "", err
+		return sdk.AccAddress{}, "", err
 	}
+
 	addr, err := k.GetAddress()
 	if err != nil {
 		return nil, "", err
 	}
+
 	return addr, secret, nil
 }
 
 // GenerateSaveCoinKey returns the address of a public key, along with the secret
 // phrase to recover the private key.
-func GenerateSaveCoinKey(keybase keyring.Keyring, keyName string, overwrite bool, algo keyring.SignatureAlgo) (sdk.AccAddress, string, error) {
+func GenerateSaveCoinKey(
+	keybase keyring.Keyring,
+	keyName, mnemonic string,
+	overwrite bool,
+	algo keyring.SignatureAlgo,
+) (sdk.AccAddress, string, error) {
 	exists := false
 	_, err := keybase.Key(keyName)
 	if err == nil {
@@ -34,25 +41,33 @@ func GenerateSaveCoinKey(keybase keyring.Keyring, keyName string, overwrite bool
 
 	// ensure no overwrite
 	if !overwrite && exists {
-		return sdk.AccAddress([]byte{}), "", fmt.Errorf(
-			"key already exists, overwrite is disabled")
+		return sdk.AccAddress{}, "", fmt.Errorf("key already exists, overwrite is disabled")
 	}
 
-	// generate a private key, with recovery phrase
+	// remove the old key by name if it exists
 	if exists {
-		err = keybase.Delete(keyName)
-		if err != nil {
-			return sdk.AccAddress([]byte{}), "", fmt.Errorf(
-				"failed to overwrite key")
+		if err = keybase.Delete(keyName); err != nil {
+			return sdk.AccAddress{}, "", fmt.Errorf("failed to overwrite key")
 		}
 	}
 
-	k, secret, err := keybase.NewMnemonic(keyName, keyring.English, sdk.GetConfig().GetFullBIP44Path(), keyring.DefaultBIP39Passphrase, algo)
+	var (
+		record *keyring.Record
+		secret string
+	)
+
+	// generate or recover a new account
+	if mnemonic != "" {
+		secret = mnemonic
+		record, err = keybase.NewAccount(keyName, mnemonic, keyring.DefaultBIP39Passphrase, sdk.GetConfig().GetFullBIP44Path(), algo)
+	} else {
+		record, secret, err = keybase.NewMnemonic(keyName, keyring.English, sdk.GetConfig().GetFullBIP44Path(), keyring.DefaultBIP39Passphrase, algo)
+	}
 	if err != nil {
-		return sdk.AccAddress([]byte{}), "", err
+		return sdk.AccAddress{}, "", err
 	}
 
-	addr, err := k.GetAddress()
+	addr, err := record.GetAddress()
 	if err != nil {
 		return nil, "", err
 	}

server/init_test.go

@@ -33,7 +33,7 @@ func TestGenerateSaveCoinKey(t *testing.T) {
 	kb, err := keyring.New(t.Name(), "test", t.TempDir(), nil, encCfg.Codec)
 	require.NoError(t, err)
 
-	addr, mnemonic, err := server.GenerateSaveCoinKey(kb, "keyname", false, hd.Secp256k1)
+	addr, mnemonic, err := server.GenerateSaveCoinKey(kb, "keyname", "", false, hd.Secp256k1)
 	require.NoError(t, err)
 
 	// Test key was actually saved
@@ -59,15 +59,15 @@ func TestGenerateSaveCoinKeyOverwriteFlag(t *testing.T) {
 	require.NoError(t, err)
 
 	keyname := "justakey"
-	addr1, _, err := server.GenerateSaveCoinKey(kb, keyname, false, hd.Secp256k1)
+	addr1, _, err := server.GenerateSaveCoinKey(kb, keyname, "", false, hd.Secp256k1)
 	require.NoError(t, err)
 
 	// Test overwrite with overwrite=false
-	_, _, err = server.GenerateSaveCoinKey(kb, keyname, false, hd.Secp256k1)
+	_, _, err = server.GenerateSaveCoinKey(kb, keyname, "", false, hd.Secp256k1)
 	require.Error(t, err)
 
 	// Test overwrite with overwrite=true
-	addr2, _, err := server.GenerateSaveCoinKey(kb, keyname, true, hd.Secp256k1)
+	addr2, _, err := server.GenerateSaveCoinKey(kb, keyname, "", true, hd.Secp256k1)
 	require.NoError(t, err)
 
 	require.NotEqual(t, addr1, addr2)

simapp/simd/cmd/testnet.go

@@ -263,7 +263,7 @@ func initTestnetFiles(
 			return err
 		}
 
-		addr, secret, err := server.GenerateSaveCoinKey(kb, nodeDirName, true, algo)
+		addr, secret, err := server.GenerateSaveCoinKey(kb, nodeDirName, "", true, algo)
 		if err != nil {
 			_ = os.RemoveAll(args.outputDir)
 			return err

testutil/network/network.go

@@ -80,6 +80,7 @@ type Config struct {
 	TimeoutCommit    time.Duration              // the consensus commitment timeout
 	ChainID          string                     // the network chain-id
 	NumValidators    int                        // the total number of validators to create and bond
+	Mnemonics        []string                   // custom user-provided validator operator mnemonics
 	BondDenom        string                     // the staking bond denomination
 	MinGasPrices     string                     // the minimum gas prices each validator will accept
 	AccountTokens    sdk.Int                    // the amount of unique validator tokens (e.g. 1000node0)
@@ -327,6 +328,7 @@ func New(l Logger, baseDir string, cfg Config) (*Network, error) {
 		if err != nil {
 			return nil, err
 		}
+
 		tmCfg.P2P.ListenAddress = p2pAddr
 		tmCfg.P2P.AddrBookStrict = false
 		tmCfg.P2P.AllowDuplicateIP = true
@@ -335,6 +337,7 @@ func New(l Logger, baseDir string, cfg Config) (*Network, error) {
 		if err != nil {
 			return nil, err
 		}
+
 		nodeIDs[i] = nodeID
 		valPubKeys[i] = pubKey
 
@@ -349,7 +352,12 @@ func New(l Logger, baseDir string, cfg Config) (*Network, error) {
 			return nil, err
 		}
 
-		addr, secret, err := server.GenerateSaveCoinKey(kb, nodeDirName, true, algo)
+		var mnemonic string
+		if i < len(cfg.Mnemonics) {
+			mnemonic = cfg.Mnemonics[i]
+		}
+
+		addr, secret, err := server.GenerateSaveCoinKey(kb, nodeDirName, mnemonic, true, algo)
 		if err != nil {
 			return nil, err
 		}