feat: allow loading config from io.Reader

Signed-off-by: Jakub Warczarek <[email protected]>

registry/remote/credentials/file_store.go

@@ -54,11 +54,11 @@ func NewFileStore(configPath string) (*FileStore, error) {
 	if err != nil {
 		return nil, err
 	}
-	return newFileStore(cfg), nil
+	return NewFileStoreFromConfig(cfg), nil
 }
 
-// newFileStore creates a file credentials store based on the given config instance.
-func newFileStore(cfg *config.Config) *FileStore {
+// NewFileStoreFromConfig creates a file credentials store based on the given config instance.
+func NewFileStoreFromConfig(cfg *config.Config) *FileStore {
 	return &FileStore{config: cfg}
 }
 

registry/remote/credentials/internal/config/config.go

@@ -21,6 +21,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
 	"os"
 	"path/filepath"
 	"strings"
@@ -93,7 +94,7 @@ func (ac AuthConfig) Credential() (auth.Credential, error) {
 //   - https://docs.docker.com/engine/reference/commandline/cli/#docker-cli-configuration-file-configjson-properties
 //   - https://github.com/docker/cli/blob/v24.0.0-beta.2/cli/config/configfile/file.go#L17-L44
 type Config struct {
-	// path is the path to the config file.
+	// path is the path to the config file. When config was loaded from memory, path is empty.
 	path string
 	// rwLock is a read-write-lock for the file store.
 	rwLock sync.RWMutex
@@ -113,11 +114,11 @@ type Config struct {
 
 // Load loads Config from the given config path.
 func Load(configPath string) (*Config, error) {
-	cfg := &Config{path: configPath}
 	configFile, err := os.Open(configPath)
 	if err != nil {
 		if os.IsNotExist(err) {
 			// init content and caches if the content file does not exist
+			cfg := &Config{path: configPath}
 			cfg.content = make(map[string]json.RawMessage)
 			cfg.authsCache = make(map[string]json.RawMessage)
 			return cfg, nil
@@ -126,9 +127,21 @@ func Load(configPath string) (*Config, error) {
 	}
 	defer configFile.Close()
 
-	// decode config content if the config file exists
-	if err := json.NewDecoder(configFile).Decode(&cfg.content); err != nil {
-		return nil, fmt.Errorf("failed to decode config file at %s: %w: %v", configPath, ErrInvalidConfigFormat, err)
+	cfg, err := LoadFromReader(configFile)
+	if err != nil {
+		return nil, err
+	}
+	cfg.path = configPath
+	return cfg, nil
+}
+
+// LoadFromReader loads Config from the given io.Reader.
+// Path can be set by SetPath to save the config,
+// otherwise all changes happen in memory.
+func LoadFromReader(r io.Reader) (*Config, error) {
+	cfg := &Config{}
+	if err := json.NewDecoder(r).Decode(&cfg.content); err != nil {
+		return nil, fmt.Errorf("failed to decode config file: %w: %v", ErrInvalidConfigFormat, err)
 	}
 
 	if credsStoreBytes, ok := cfg.content[configFieldCredentialsStore]; ok {
@@ -195,7 +208,7 @@ func (cfg *Config) PutCredential(serverAddress string, cred auth.Credential) err
 		return fmt.Errorf("failed to marshal auth field: %w", err)
 	}
 	cfg.authsCache[serverAddress] = authCfgBytes
-	return cfg.saveFile()
+	return cfg.SaveFile()
 }
 
 // DeleteAuthConfig deletes the corresponding credential for serverAddress.
@@ -208,7 +221,7 @@ func (cfg *Config) DeleteCredential(serverAddress string) error {
 		return nil
 	}
 	delete(cfg.authsCache, serverAddress)
-	return cfg.saveFile()
+	return cfg.SaveFile()
 }
 
 // GetCredentialHelper returns the credential helpers for serverAddress.
@@ -225,17 +238,23 @@ func (cfg *Config) CredentialsStore() string {
 }
 
 // Path returns the path to the config file.
+// It's empty if the config was loaded from memory.
 func (cfg *Config) Path() string {
 	return cfg.path
 }
 
+// SetPath sets the path to the config file.
+func (cfg *Config) SetPath(path string) {
+	cfg.path = path
+}
+
 // SetCredentialsStore puts the configured credentials store.
 func (cfg *Config) SetCredentialsStore(credsStore string) error {
 	cfg.rwLock.Lock()
 	defer cfg.rwLock.Unlock()
 
 	cfg.credentialsStore = credsStore
-	return cfg.saveFile()
+	return cfg.SaveFile()
 }
 
 // IsAuthConfigured returns whether there is authentication configured in this
@@ -246,8 +265,13 @@ func (cfg *Config) IsAuthConfigured() bool {
 		len(cfg.authsCache) > 0
 }
 
-// saveFile saves Config into the file.
-func (cfg *Config) saveFile() (returnErr error) {
+// SaveFile saves Config into the file.
+// In case when the Path() returns empty, it does nothing.
+func (cfg *Config) SaveFile() (returnErr error) {
+	if cfg.path == "" {
+		return nil
+	}
+
 	// marshal content
 	// credentialHelpers is skipped as it's never set
 	if cfg.credentialsStore != "" {

registry/remote/credentials/internal/config/config_test.go

@@ -18,6 +18,7 @@ package config
 import (
 	"encoding/json"
 	"errors"
+	"fmt"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -80,13 +81,64 @@ func TestLoad_badFormat(t *testing.T) {
 		},
 	}
 	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
+		t.Run(fmt.Sprintf("%s-from-file", tt.name), func(t *testing.T) {
 			_, err := Load(tt.configPath)
 			if (err != nil) != tt.wantErr {
 				t.Errorf("Load() error = %v, wantErr %v", err, tt.wantErr)
 				return
 			}
 		})
+		t.Run(fmt.Sprintf("%s-from-reader", tt.name), func(t *testing.T) {
+			r, err := os.Open(tt.configPath)
+			if err != nil {
+				t.Fatal("failed to open test file:", err)
+			}
+			defer r.Close()
+			_, err = LoadFromReader(r)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Load() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+		})
+	}
+}
+
+func TestLoadFromReader_setPathAndSave(t *testing.T) {
+	const testCfgPath = "../../testdata/valid_auths_config.json"
+	r, err := os.Open(testCfgPath)
+	if err != nil {
+		t.Fatal("failed to open test file:", err)
+	}
+	defer r.Close()
+	cfg, err := LoadFromReader(r)
+	if err != nil {
+		t.Fatal("LoadFromReader() error =", err)
+	}
+	tempDir := t.TempDir()
+	configPath := filepath.Join(tempDir, "config.json")
+	cfg.SetPath(configPath)
+	cfg.SaveFile()
+	if cfg.Path() != configPath {
+		t.Errorf("Config.Path() = %s, want %s", cfg.Path(), configPath)
+	}
+
+	// Verify content.
+	orgContent, err := os.ReadFile(testCfgPath)
+	if err != nil {
+		t.Fatalf("failed to read original config file: %v", err)
+	}
+	var orgCfg configtest.Config
+	json.Unmarshal(orgContent, &orgCfg)
+
+	savedContent, err := os.ReadFile(configPath)
+	if err != nil {
+		t.Fatalf("failed to read saved config file: %v", err)
+	}
+	var savedCfg configtest.Config
+	json.Unmarshal(savedContent, &savedCfg)
+
+	if !reflect.DeepEqual(orgCfg, savedCfg) {
+		t.Errorf("Saved config = %v, want %v", savedCfg, orgCfg)
 	}
 }
 
@@ -1278,8 +1330,8 @@ func TestConfig_saveFile(t *testing.T) {
 			}
 			cfg.credentialsStore = tt.newCfg.CredentialsStore
 			cfg.credentialHelpers = tt.newCfg.CredentialHelpers
-			if err := cfg.saveFile(); err != nil {
-				t.Fatal("saveFile() error =", err)
+			if err := cfg.SaveFile(); err != nil {
+				t.Fatal("SaveFile() error =", err)
 			}
 
 			// verify config file

registry/remote/credentials/store.go

@@ -193,7 +193,7 @@ func (ds *DynamicStore) getStore(serverAddress string) Store {
 		return NewNativeStore(helper)
 	}
 
-	fs := newFileStore(ds.config)
+	fs := NewFileStoreFromConfig(ds.config)
 	fs.DisablePut = !ds.options.AllowPlaintextPut
 	return fs
 }