Improve Credential Errors

pkg/secrethub/client.go

@@ -82,6 +82,8 @@ type Client struct {
 	// These are cached
 	repoIndexKeys map[api.RepoPath]*crypto.SymmetricKey
 
+	defaultPassphraseReader credentials.Reader
+
 	appInfo   []*AppInfo
 	ConfigDir *configdir.Dir
 }
@@ -119,9 +121,10 @@ func (i AppInfo) ValidateName() error {
 // If no key credential could be found, a Client is returned that can only be used for unauthenticated routes.
 func NewClient(with ...ClientOption) (*Client, error) {
 	client := &Client{
-		httpClient:    http.NewClient(),
-		repoIndexKeys: make(map[api.RepoPath]*crypto.SymmetricKey),
-		appInfo:       []*AppInfo{},
+		httpClient:              http.NewClient(),
+		repoIndexKeys:           make(map[api.RepoPath]*crypto.SymmetricKey),
+		appInfo:                 []*AppInfo{},
+		defaultPassphraseReader: credentials.FromEnv("SECRETHUB_CREDENTIAL_PASSPHRASE"),
 	}
 	err := client.with(with...)
 	if err != nil {
@@ -144,7 +147,7 @@ func NewClient(with ...ClientOption) (*Client, error) {
 		var provider credentials.Provider
 		switch strings.ToLower(identityProvider) {
 		case "", "key":
-			provider = credentials.UseKey(client.DefaultCredential())
+			provider = credentials.UseKey(client.DefaultCredential()).Passphrase(client.defaultPassphraseReader)
 		case "aws":
 			provider = credentials.UseAWS()
 		case "gcp":
@@ -264,9 +267,10 @@ func (c *Client) with(options ...ClientOption) error {
 // sourcing it either from the SECRETHUB_CREDENTIAL environment variable or
 // from the configuration directory.
 func (c *Client) DefaultCredential() credentials.Reader {
-	envCredential := os.Getenv("SECRETHUB_CREDENTIAL")
+	const credentialEnvironmentVariable = "SECRETHUB_CREDENTIAL"
+	envCredential := os.Getenv(credentialEnvironmentVariable)
 	if envCredential != "" {
-		return credentials.FromString(envCredential)
+		return credentials.FromEnv(credentialEnvironmentVariable)
 	}
 
 	return c.ConfigDir.Credential()

pkg/secrethub/client_options.go

@@ -78,3 +78,12 @@ func WithCredentials(provider credentials.Provider) ClientOption {
 		return nil
 	}
 }
+
+// WithDefaultPassphraseReader sets a default passphrase reader that is used for decrypting an encrypted key credential
+// if no credential is set explicitly.
+func WithDefaultPassphraseReader(reader credentials.Reader) ClientOption {
+	return func(c *Client) error {
+		c.defaultPassphraseReader = reader
+		return nil
+	}
+}

pkg/secrethub/configdir/dir.go

@@ -77,6 +77,11 @@ func (f *CredentialFile) Path() string {
 	return f.path
 }
 
+// Source returns the path to the credential file.
+func (f *CredentialFile) Source() string {
+	return f.path
+}
+
 // Write writes the given bytes to the credential file.
 func (f *CredentialFile) Write(data []byte) error {
 	err := os.MkdirAll(filepath.Dir(f.path), os.FileMode(0700))

pkg/secrethub/credentials/encoding.go

@@ -25,6 +25,7 @@ var (
 	ErrCannotDecodeCredentialPayload     = errCredentials.Code("invalid_credential_header").ErrorPref("cannot decode credential payload: %v")
 	ErrCannotDecodeEncryptedCredential   = errCredentials.Code("cannot_decode_encrypted_credential").Error("cannot decode an encrypted credential without a key")
 	ErrCannotDecryptCredential           = errCredentials.Code("cannot_decrypt_credential").Error("passphrase is incorrect")
+	ErrNeedPassphrase                    = errCredentials.Code("credential_passphrase_required").Error("credential is password-protected. Configure a credential passphrase through the SECRETHUB_CREDENTIAL_PASSPHRASE environment variable or use a credential that is not password-protected")
 	ErrMalformedCredential               = errCredentials.Code("malformed_credential").ErrorPref("credential is malformed: %v")
 	ErrInvalidKey                        = errCredentials.Code("invalid_key").Error("the given key is not valid for the encryption algorithm")
 )

pkg/secrethub/credentials/key.go

@@ -2,12 +2,23 @@ package credentials
 
 import (
 	"errors"
+	"fmt"
+	"os"
 
 	"github.com/secrethub/secrethub-go/internals/auth"
 	"github.com/secrethub/secrethub-go/internals/crypto"
 	"github.com/secrethub/secrethub-go/pkg/secrethub/internals/http"
 )
 
+type ErrLoadingCredential struct {
+	Location string
+	Err      error
+}
+
+func (e ErrLoadingCredential) Error() string {
+	return "load credential " + e.Location + ": " + e.Err.Error()
+}
+
 // Key is a credential that uses a local key for all its operations.
 type Key struct {
 	key              *RSACredential
@@ -69,8 +80,17 @@ func ImportKey(credentialReader, passphraseReader Reader) (Key, error) {
 		return Key{}, err
 	}
 	if encoded.IsEncrypted() {
+		const credentialPassphraseEnvVar = "SECRETHUB_CREDENTIAL_PASSPHRASE"
+		envPassphrase := os.Getenv(credentialPassphraseEnvVar)
+		if envPassphrase != "" {
+			credential, err := decryptKey([]byte(envPassphrase), encoded)
+			if err != nil {
+				return Key{}, fmt.Errorf("decrypting credential with passphrase read from $%s: %v", credentialPassphraseEnvVar, err)
+			}
+			return Key{key: credential}, nil
+		}
 		if passphraseReader == nil {
-			return Key{}, errors.New("need passphrase")
+			return Key{}, ErrNeedPassphrase
 		}
 
 		// Try up to three times to get the correct passphrase.

pkg/secrethub/credentials/providers.go

@@ -40,6 +40,12 @@ func (k KeyProvider) Passphrase(passphraseReader Reader) Provider {
 func (k KeyProvider) Provide(httpClient *http.Client) (auth.Authenticator, Decrypter, error) {
 	key, err := ImportKey(k.credentialReader, k.passphraseReader)
 	if err != nil {
+		if source, ok := k.credentialReader.(CredentialSource); ok {
+			return nil, nil, ErrLoadingCredential{
+				Location: source.Source(),
+				Err:      err,
+			}
+		}
 		return nil, nil, err
 	}
 	return key.Provide(httpClient)
@@ -52,3 +58,9 @@ type providerFunc func(*http.Client) (auth.Authenticator, Decrypter, error)
 func (f providerFunc) Provide(httpClient *http.Client) (auth.Authenticator, Decrypter, error) {
 	return f(httpClient)
 }
+
+// CredentialSource should be implemented by credential readers to allow returning credential reading errors
+// that include the credentials source (e.g. path to credential file, environment variable etc.).
+type CredentialSource interface {
+	Source() string
+}

pkg/secrethub/credentials/readers.go

@@ -14,15 +14,15 @@ type Reader interface {
 // FromFile returns a reader that reads the contents of a file,
 // e.g. a credential or a passphrase.
 func FromFile(path string) Reader {
-	return readerFunc(func() ([]byte, error) {
+	return newReader(path, func() ([]byte, error) {
 		return ioutil.ReadFile(path)
 	})
 }
 
 // FromEnv returns a reader that reads the contents of an
 // environment variable, e.g. a credential or a passphrase.
 func FromEnv(key string) Reader {
-	return readerFunc(func() ([]byte, error) {
+	return newReader("$"+key, func() ([]byte, error) {
 		return []byte(os.Getenv(key)), nil
 	})
 }
@@ -43,10 +43,30 @@ func FromString(raw string) Reader {
 	})
 }
 
-// readerFunc is a helper function to create a reader from any func() ([]byte, error).
 type readerFunc func() ([]byte, error)
 
+func (r readerFunc) Read() ([]byte, error) {
+	return r()
+}
+
+// newReader is a helper function to create a reader with a source from any func() ([]byte, error).
+func newReader(source string, read func() ([]byte, error)) Reader {
+	return reader{
+		source:   source,
+		readFunc: read,
+	}
+}
+
+type reader struct {
+	source   string
+	readFunc func() ([]byte, error)
+}
+
+func (r reader) Source() string {
+	return r.source
+}
+
 // Read implements the Reader interface.
-func (f readerFunc) Read() ([]byte, error) {
-	return f()
+func (r reader) Read() ([]byte, error) {
+	return r.readFunc()
 }