backend: add standardized Config.ApplyEnvironment

This removes the backend specific special cases while parsing the
configuration in `global.go`.

cmd/restic/global.go

@@ -535,112 +535,21 @@ func OpenRepository(ctx context.Context, opts GlobalOptions) (*repository.Reposi
 }
 
 func parseConfig(loc location.Location, opts options.Options) (interface{}, error) {
+	cfg := loc.Config
+	if cfg, ok := cfg.(restic.ApplyEnvironmenter); ok {
+		if err := cfg.ApplyEnvironment(""); err != nil {
+			return nil, err
+		}
+	}
+
 	// only apply options for a particular backend here
 	opts = opts.Extract(loc.Scheme)
-
-	switch loc.Scheme {
-	case "local":
-		cfg := loc.Config.(*local.Config)
 	if err := opts.Apply(loc.Scheme, cfg); err != nil {
 		return nil, err
 	}
 
-		debug.Log("opening local repository at %#v", cfg)
+	debug.Log("opening %v repository at %#v", loc.Scheme, cfg)
 	return cfg, nil
-
-	case "sftp":
-		cfg := loc.Config.(*sftp.Config)
-		if err := opts.Apply(loc.Scheme, cfg); err != nil {
-			return nil, err
-		}
-
-		debug.Log("opening sftp repository at %#v", cfg)
-		return cfg, nil
-
-	case "s3":
-		cfg := loc.Config.(*s3.Config)
-
-		if err := s3.ApplyEnvironment(cfg); err != nil {
-			return nil, err
-		}
-		if err := opts.Apply(loc.Scheme, cfg); err != nil {
-			return nil, err
-		}
-
-		debug.Log("opening s3 repository at %#v", cfg)
-		return cfg, nil
-
-	case "gs":
-		cfg := loc.Config.(*gs.Config)
-
-		if err := gs.ApplyEnvironment(cfg); err != nil {
-			return nil, err
-		}
-		if err := opts.Apply(loc.Scheme, cfg); err != nil {
-			return nil, err
-		}
-
-		debug.Log("opening gs repository at %#v", cfg)
-		return cfg, nil
-
-	case "azure":
-		cfg := loc.Config.(*azure.Config)
-
-		if err := azure.ApplyEnvironment(cfg); err != nil {
-			return nil, err
-		}
-		if err := opts.Apply(loc.Scheme, cfg); err != nil {
-			return nil, err
-		}
-
-		debug.Log("opening gs repository at %#v", cfg)
-		return cfg, nil
-
-	case "swift":
-		cfg := loc.Config.(*swift.Config)
-
-		if err := swift.ApplyEnvironment("", cfg); err != nil {
-			return nil, err
-		}
-
-		if err := opts.Apply(loc.Scheme, cfg); err != nil {
-			return nil, err
-		}
-
-		debug.Log("opening swift repository at %#v", cfg)
-		return cfg, nil
-
-	case "b2":
-		cfg := loc.Config.(*b2.Config)
-
-		if err := b2.ApplyEnvironment(cfg); err != nil {
-			return nil, err
-		}
-		if err := opts.Apply(loc.Scheme, cfg); err != nil {
-			return nil, err
-		}
-
-		debug.Log("opening b2 repository at %#v", cfg)
-		return cfg, nil
-	case "rest":
-		cfg := loc.Config.(*rest.Config)
-		if err := opts.Apply(loc.Scheme, cfg); err != nil {
-			return nil, err
-		}
-
-		debug.Log("opening rest repository at %#v", cfg)
-		return cfg, nil
-	case "rclone":
-		cfg := loc.Config.(*rclone.Config)
-		if err := opts.Apply(loc.Scheme, cfg); err != nil {
-			return nil, err
-		}
-
-		debug.Log("opening rest repository at %#v", cfg)
-		return cfg, nil
-	}
-
-	return nil, errors.Fatalf("invalid backend: %q", loc.Scheme)
 }
 
 // Open the backend specified by a location config.

internal/backend/azure/config.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/restic/restic/internal/errors"
 	"github.com/restic/restic/internal/options"
+	"github.com/restic/restic/internal/restic"
 )
 
 // Config contains all configuration necessary to connect to an azure compatible
@@ -55,19 +56,20 @@ func ParseConfig(s string) (*Config, error) {
 	return &cfg, nil
 }
 
+var _ restic.ApplyEnvironmenter = &Config{}
+
 // ApplyEnvironment saves values from the environment to the config.
-func ApplyEnvironment(cfgRaw interface{}) error {
+func (cfg *Config) ApplyEnvironment(prefix string) error {
-	cfg := cfgRaw.(*Config)
 	if cfg.AccountName == "" {
-		cfg.AccountName = os.Getenv("AZURE_ACCOUNT_NAME")
+		cfg.AccountName = os.Getenv(prefix + "AZURE_ACCOUNT_NAME")
 	}
 
 	if cfg.AccountKey.String() == "" {
-		cfg.AccountKey = options.NewSecretString(os.Getenv("AZURE_ACCOUNT_KEY"))
+		cfg.AccountKey = options.NewSecretString(os.Getenv(prefix + "AZURE_ACCOUNT_KEY"))
 	}
 
 	if cfg.AccountSAS.String() == "" {
-		cfg.AccountSAS = options.NewSecretString(os.Getenv("AZURE_ACCOUNT_SAS"))
+		cfg.AccountSAS = options.NewSecretString(os.Getenv(prefix + "AZURE_ACCOUNT_SAS"))
 	}
 	return nil
 }

internal/backend/b2/config.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/restic/restic/internal/errors"
 	"github.com/restic/restic/internal/options"
+	"github.com/restic/restic/internal/restic"
 )
 
 // Config contains all configuration necessary to connect to an b2 compatible
@@ -81,11 +82,12 @@ func ParseConfig(s string) (*Config, error) {
 	return &cfg, nil
 }
 
+var _ restic.ApplyEnvironmenter = &Config{}
+
 // ApplyEnvironment saves values from the environment to the config.
-func ApplyEnvironment(cfgRaw interface{}) error {
+func (cfg *Config) ApplyEnvironment(prefix string) error {
-	cfg := cfgRaw.(*Config)
 	if cfg.AccountID == "" {
-		cfg.AccountID = os.Getenv("B2_ACCOUNT_ID")
+		cfg.AccountID = os.Getenv(prefix + "B2_ACCOUNT_ID")
 	}
 
 	if cfg.AccountID == "" {
@@ -93,7 +95,7 @@ func ApplyEnvironment(cfgRaw interface{}) error {
 	}
 
 	if cfg.Key.String() == "" {
-		cfg.Key = options.NewSecretString(os.Getenv("B2_ACCOUNT_KEY"))
+		cfg.Key = options.NewSecretString(os.Getenv(prefix + "B2_ACCOUNT_KEY"))
 	}
 
 	if cfg.Key.String() == "" {

internal/backend/gs/config.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/restic/restic/internal/errors"
 	"github.com/restic/restic/internal/options"
+	"github.com/restic/restic/internal/restic"
 )
 
 // Config contains all configuration necessary to connect to a Google Cloud Storage
@@ -58,11 +59,12 @@ func ParseConfig(s string) (*Config, error) {
 	return &cfg, nil
 }
 
+var _ restic.ApplyEnvironmenter = &Config{}
+
 // ApplyEnvironment saves values from the environment to the config.
-func ApplyEnvironment(cfgRaw interface{}) error {
+func (cfg *Config) ApplyEnvironment(prefix string) error {
-	cfg := cfgRaw.(*Config)
 	if cfg.ProjectID == "" {
-		cfg.ProjectID = os.Getenv("GOOGLE_PROJECT_ID")
+		cfg.ProjectID = os.Getenv(prefix + "GOOGLE_PROJECT_ID")
 	}
 	return nil
 }

internal/backend/s3/config.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/restic/restic/internal/errors"
 	"github.com/restic/restic/internal/options"
+	"github.com/restic/restic/internal/restic"
 )
 
 // Config contains all configuration necessary to connect to an s3 compatible
@@ -93,15 +94,16 @@ func createConfig(endpoint, bucket, prefix string, useHTTP bool) (*Config, error
 	return &cfg, nil
 }
 
+var _ restic.ApplyEnvironmenter = &Config{}
+
 // ApplyEnvironment saves values from the environment to the config.
-func ApplyEnvironment(cfgRaw interface{}) error {
+func (cfg *Config) ApplyEnvironment(prefix string) error {
-	cfg := cfgRaw.(*Config)
 	if cfg.KeyID == "" {
-		cfg.KeyID = os.Getenv("AWS_ACCESS_KEY_ID")
+		cfg.KeyID = os.Getenv(prefix + "AWS_ACCESS_KEY_ID")
 	}
 
 	if cfg.Secret.String() == "" {
-		cfg.Secret = options.NewSecretString(os.Getenv("AWS_SECRET_ACCESS_KEY"))
+		cfg.Secret = options.NewSecretString(os.Getenv(prefix + "AWS_SECRET_ACCESS_KEY"))
 	}
 
 	if cfg.KeyID == "" && cfg.Secret.String() != "" {
@@ -111,7 +113,7 @@ func ApplyEnvironment(cfgRaw interface{}) error {
 	}
 
 	if cfg.Region == "" {
-		cfg.Region = os.Getenv("AWS_DEFAULT_REGION")
+		cfg.Region = os.Getenv(prefix + "AWS_DEFAULT_REGION")
 	}
 
 	return nil

internal/backend/swift/config.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/restic/restic/internal/errors"
 	"github.com/restic/restic/internal/options"
+	"github.com/restic/restic/internal/restic"
 )
 
 // Config contains basic configuration needed to specify swift location for a swift server
@@ -73,45 +74,46 @@ func ParseConfig(s string) (*Config, error) {
 	return &cfg, nil
 }
 
+var _ restic.ApplyEnvironmenter = &Config{}
+
 // ApplyEnvironment saves values from the environment to the config.
-func ApplyEnvironment(prefix string, cfg interface{}) error {
+func (cfg *Config) ApplyEnvironment(prefix string) error {
-	c := cfg.(*Config)
 	for _, val := range []struct {
 		s   *string
 		env string
 	}{
 		// v2/v3 specific
-		{&c.UserName, prefix + "OS_USERNAME"},
+		{&cfg.UserName, prefix + "OS_USERNAME"},
-		{&c.APIKey, prefix + "OS_PASSWORD"},
+		{&cfg.APIKey, prefix + "OS_PASSWORD"},
-		{&c.Region, prefix + "OS_REGION_NAME"},
+		{&cfg.Region, prefix + "OS_REGION_NAME"},
-		{&c.AuthURL, prefix + "OS_AUTH_URL"},
+		{&cfg.AuthURL, prefix + "OS_AUTH_URL"},
 
 		// v3 specific
-		{&c.UserID, prefix + "OS_USER_ID"},
+		{&cfg.UserID, prefix + "OS_USER_ID"},
-		{&c.Domain, prefix + "OS_USER_DOMAIN_NAME"},
+		{&cfg.Domain, prefix + "OS_USER_DOMAIN_NAME"},
-		{&c.DomainID, prefix + "OS_USER_DOMAIN_ID"},
+		{&cfg.DomainID, prefix + "OS_USER_DOMAIN_ID"},
-		{&c.Tenant, prefix + "OS_PROJECT_NAME"},
+		{&cfg.Tenant, prefix + "OS_PROJECT_NAME"},
-		{&c.TenantDomain, prefix + "OS_PROJECT_DOMAIN_NAME"},
+		{&cfg.TenantDomain, prefix + "OS_PROJECT_DOMAIN_NAME"},
-		{&c.TenantDomainID, prefix + "OS_PROJECT_DOMAIN_ID"},
+		{&cfg.TenantDomainID, prefix + "OS_PROJECT_DOMAIN_ID"},
-		{&c.TrustID, prefix + "OS_TRUST_ID"},
+		{&cfg.TrustID, prefix + "OS_TRUST_ID"},
 
 		// v2 specific
-		{&c.TenantID, prefix + "OS_TENANT_ID"},
+		{&cfg.TenantID, prefix + "OS_TENANT_ID"},
-		{&c.Tenant, prefix + "OS_TENANT_NAME"},
+		{&cfg.Tenant, prefix + "OS_TENANT_NAME"},
 
 		// v1 specific
-		{&c.AuthURL, prefix + "ST_AUTH"},
+		{&cfg.AuthURL, prefix + "ST_AUTH"},
-		{&c.UserName, prefix + "ST_USER"},
+		{&cfg.UserName, prefix + "ST_USER"},
-		{&c.APIKey, prefix + "ST_KEY"},
+		{&cfg.APIKey, prefix + "ST_KEY"},
 
 		// Application Credential auth
-		{&c.ApplicationCredentialID, prefix + "OS_APPLICATION_CREDENTIAL_ID"},
+		{&cfg.ApplicationCredentialID, prefix + "OS_APPLICATION_CREDENTIAL_ID"},
-		{&c.ApplicationCredentialName, prefix + "OS_APPLICATION_CREDENTIAL_NAME"},
+		{&cfg.ApplicationCredentialName, prefix + "OS_APPLICATION_CREDENTIAL_NAME"},
 
 		// Manual authentication
-		{&c.StorageURL, prefix + "OS_STORAGE_URL"},
+		{&cfg.StorageURL, prefix + "OS_STORAGE_URL"},
 
-		{&c.DefaultContainerPolicy, prefix + "SWIFT_DEFAULT_CONTAINER_POLICY"},
+		{&cfg.DefaultContainerPolicy, prefix + "SWIFT_DEFAULT_CONTAINER_POLICY"},
 	} {
 		if *val.s == "" {
 			*val.s = os.Getenv(val.env)
@@ -121,8 +123,8 @@ func ApplyEnvironment(prefix string, cfg interface{}) error {
 		s   *options.SecretString
 		env string
 	}{
-		{&c.ApplicationCredentialSecret, prefix + "OS_APPLICATION_CREDENTIAL_SECRET"},
+		{&cfg.ApplicationCredentialSecret, prefix + "OS_APPLICATION_CREDENTIAL_SECRET"},
-		{&c.AuthToken, prefix + "OS_AUTH_TOKEN"},
+		{&cfg.AuthToken, prefix + "OS_AUTH_TOKEN"},
 	} {
 		if val.s.String() == "" {
 			*val.s = options.NewSecretString(os.Getenv(val.env))

internal/backend/swift/swift_test.go

@@ -48,7 +48,7 @@ func newSwiftTestSuite(t testing.TB) *test.Suite[swift.Config] {
 				return nil, err
 			}
 
-			if err = swift.ApplyEnvironment("RESTIC_TEST_", &cfg); err != nil {
+			if err = cfg.ApplyEnvironment("RESTIC_TEST_"); err != nil {
 				return nil, err
 			}
 			cfg.Prefix += fmt.Sprintf("/test-%d", time.Now().UnixNano())

internal/restic/backend.go

@@ -80,3 +80,8 @@ type FileInfo struct {
 	Size int64
 	Name string
 }
+
+// ApplyEnvironmenter fills in a backend configuration from the environment
+type ApplyEnvironmenter interface {
+	ApplyEnvironment(prefix string) error
+}