feat(refresh): add user public key to authorized_keys on refresh

When keys are refreshed (brev refresh, brev shell, brev open, etc.),
write the user's public key to ~/.ssh/authorized_keys if not already
present. Appends without overwriting existing keys.

Author: theFong

pkg/cmd/refresh/refresh.go

@@ -22,6 +22,7 @@ type RefreshStore interface {
 	ssh.SSHConfigurerV2Store
 	GetCurrentUser() (*entity.User, error)
 	GetCurrentUserKeys() (*entity.UserKeys, error)
+	WriteAuthorizedKey(publicKey string) error
 	Chmod(string, fs.FileMode) error
 	MkdirAll(string, fs.FileMode) error
 	GetBrevCloudflaredBinaryPath() (string, error)
@@ -62,7 +63,7 @@ func RunRefreshBetter(store RefreshStore) error {
 		return breverrors.WrapAndTrace(err)
 	}
 
-	cu, err := GetConfigUpdater(store)
+	cu, keys, err := GetConfigUpdater(store)
 	if err != nil {
 		return breverrors.WrapAndTrace(err)
 	}
@@ -72,6 +73,11 @@ func RunRefreshBetter(store RefreshStore) error {
 		return breverrors.WrapAndTrace(err)
 	}
 
+	err = store.WriteAuthorizedKey(keys.PublicKey)
+	if err != nil {
+		return breverrors.WrapAndTrace(err)
+	}
+
 	privateKeyPath, err := store.GetPrivateKeyPath()
 	if err != nil {
 		return breverrors.WrapAndTrace(err)
@@ -91,7 +97,7 @@ func RunRefresh(store RefreshStore) error {
 		return breverrors.WrapAndTrace(err)
 	}
 
-	cu, err := GetConfigUpdater(store)
+	cu, keys, err := GetConfigUpdater(store)
 	if err != nil {
 		return breverrors.WrapAndTrace(err)
 	}
@@ -101,6 +107,11 @@ func RunRefresh(store RefreshStore) error {
 		return breverrors.WrapAndTrace(err)
 	}
 
+	err = store.WriteAuthorizedKey(keys.PublicKey)
+	if err != nil {
+		return breverrors.WrapAndTrace(err)
+	}
+
 	privateKeyPath, err := store.GetPrivateKeyPath()
 	if err != nil {
 		return breverrors.WrapAndTrace(err)
@@ -139,20 +150,20 @@ func RunRefreshAsync(rstore RefreshStore) *RefreshRes {
 	return &res
 }
 
-func GetConfigUpdater(store RefreshStore) (*ssh.ConfigUpdater, error) {
+func GetConfigUpdater(store RefreshStore) (*ssh.ConfigUpdater, *entity.UserKeys, error) {
 	configs, err := ssh.GetSSHConfigs(store)
 	if err != nil {
-		return nil, breverrors.WrapAndTrace(err)
+		return nil, nil, breverrors.WrapAndTrace(err)
 	}
 
 	keys, err := store.GetCurrentUserKeys()
 	if err != nil {
-		return nil, breverrors.WrapAndTrace(err)
+		return nil, nil, breverrors.WrapAndTrace(err)
 	}
 
 	cu := ssh.NewConfigUpdater(store, configs, keys.PrivateKey)
 
-	return cu, nil
+	return cu, keys, nil
 }
 
 func GetCloudflare(refreshStore RefreshStore) store.Cloudflared {

pkg/files/files.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"strings"
 
 	breverrors "github.com/brevdev/brev-cli/pkg/errors"
 	"golang.org/x/text/encoding/charmap"
@@ -75,6 +76,10 @@ func GetSSHPrivateKeyPath(home string) string {
 	return fpath
 }
 
+func GetAuthorizedKeysPath(home string) string {
+	return filepath.Join(home, ".ssh", "authorized_keys")
+}
+
 func GetUserSSHConfigPath(home string) (string, error) {
 	sshConfigPath := filepath.Join(home, ".ssh", "config")
 	return sshConfigPath, nil
@@ -210,6 +215,39 @@ func OverwriteJSON(fs afero.Fs, filepath string, v interface{}) error {
 
 // write
 
+// WriteAuthorizedKey ensures the given public key is present in ~/.ssh/authorized_keys.
+// It appends the key only if it's not already there.
+func WriteAuthorizedKey(fs afero.Fs, publicKey string, home string) error {
+	authorizedKeysPath := GetAuthorizedKeysPath(home)
+	err := fs.MkdirAll(filepath.Dir(authorizedKeysPath), 0o700)
+	if err != nil {
+		return breverrors.WrapAndTrace(err)
+	}
+
+	publicKey = strings.TrimSpace(publicKey)
+
+	existing, err := afero.ReadFile(fs, authorizedKeysPath)
+	if err != nil && !os.IsNotExist(err) {
+		return breverrors.WrapAndTrace(err)
+	}
+
+	if strings.Contains(string(existing), publicKey) {
+		return nil
+	}
+
+	content := string(existing)
+	if len(content) > 0 && !strings.HasSuffix(content, "\n") {
+		content += "\n"
+	}
+	content += publicKey + "\n"
+
+	err = afero.WriteFile(fs, authorizedKeysPath, []byte(content), 0o600)
+	if err != nil {
+		return breverrors.WrapAndTrace(err)
+	}
+	return nil
+}
+
 func WriteSSHPrivateKey(fs afero.Fs, data string, home string) error {
 	pkPath := GetSSHPrivateKeyPath(home)
 	err := fs.MkdirAll(filepath.Dir(pkPath), defaultFilePermission)

pkg/store/ssh.go

@@ -235,6 +235,18 @@ func (f FileStore) WritePrivateKey(pem string) error {
 	return nil
 }
 
+func (f FileStore) WriteAuthorizedKey(publicKey string) error {
+	home, err := f.UserHomeDir()
+	if err != nil {
+		return breverrors.WrapAndTrace(err)
+	}
+	err = files.WriteAuthorizedKey(f.fs, publicKey, home)
+	if err != nil {
+		return breverrors.WrapAndTrace(err)
+	}
+	return nil
+}
+
 func (f FileStore) GetPrivateKeyPath() (string, error) {
 	home, err := f.UserHomeDir()
 	if err != nil {