Release v0.2.0

internal/config/config.go

@@ -21,13 +21,23 @@ type Config struct {
 	ClientSecret string `toml:"-"`
 }
 
+const configPathEnvVar = "NIX_CACHE_LOGIN_CONFIG"
+
+var systemConfigPath = "/etc/nix-cache-login/config.toml"
+
 // Load reads the config from the given path, or from the default XDG location.
 func Load(path string) (*Config, error) {
-	if path == "" {
-		path = filepath.Join(xdg.ConfigHome, "nix-cache-login", "config.toml")
-	}
-
+	path = resolveConfigPath(path)
 	data, err := os.ReadFile(path)
+	if err != nil && path == defaultXDGConfigPath() {
+		// On servers, allow a system-wide fallback when per-user XDG config is absent.
+		if systemData, systemErr := os.ReadFile(systemConfigPath); systemErr == nil {
+			data = systemData
+			err = nil
+		} else {
+			return nil, fmt.Errorf("reading config file: %w", err)
+		}
+	}
 	if err != nil {
 		return nil, fmt.Errorf("reading config file: %w", err)
 	}
@@ -55,6 +65,20 @@ func Load(path string) (*Config, error) {
 	return &cfg, nil
 }
 
+func resolveConfigPath(path string) string {
+	if path != "" {
+		return path
+	}
+	if envPath := strings.TrimSpace(os.Getenv(configPathEnvVar)); envPath != "" {
+		return envPath
+	}
+	return defaultXDGConfigPath()
+}
+
+func defaultXDGConfigPath() string {
+	return filepath.Join(xdg.ConfigHome, "nix-cache-login", "config.toml")
+}
+
 func (c *Config) validate() error {
 	if c.Issuer == "" {
 		return fmt.Errorf("config: issuer is required")

internal/config/config_test.go

@@ -4,6 +4,8 @@ import (
 	"os"
 	"path/filepath"
 	"testing"
+
+	"github.com/adrg/xdg"
 )
 
 func TestLoadValidConfig(t *testing.T) {
@@ -192,6 +194,65 @@ func TestMissingRequiredFields(t *testing.T) {
 	}
 }
 
+func TestLoadUsesNixCacheLoginConfigEnvWhenPathEmpty(t *testing.T) {
+	dir := t.TempDir()
+	cfgFile := filepath.Join(dir, "custom-config.toml")
+
+	content := `
+issuer = "https://id.example.com/realms/test"
+client_id = "nix-cache-server"
+cache_host = "cache.example.com"
+netrc_path = "/tmp/netrc"
+`
+	if err := os.WriteFile(cfgFile, []byte(content), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	t.Setenv(configPathEnvVar, cfgFile)
+	cfg, err := Load("")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if cfg.ClientID != "nix-cache-server" {
+		t.Fatalf("client_id = %q, want %q", cfg.ClientID, "nix-cache-server")
+	}
+}
+
+func TestLoadFallsBackToSystemConfigPath(t *testing.T) {
+	dir := t.TempDir()
+	systemCfg := filepath.Join(dir, "system-config.toml")
+	systemConfigPathOrig := systemConfigPath
+	systemConfigPath = systemCfg
+	defer func() {
+		systemConfigPath = systemConfigPathOrig
+	}()
+
+	content := `
+issuer = "https://id.example.com/realms/test"
+client_id = "nix-cache-server"
+cache_host = "cache.example.com"
+netrc_path = "/tmp/netrc"
+`
+	if err := os.WriteFile(systemCfg, []byte(content), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	t.Setenv(configPathEnvVar, "")
+	origConfigHome := xdg.ConfigHome
+	xdg.ConfigHome = filepath.Join(dir, "xdg-missing")
+	defer func() {
+		xdg.ConfigHome = origConfigHome
+	}()
+
+	cfg, err := Load("")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if cfg.ClientID != "nix-cache-server" {
+		t.Fatalf("client_id = %q, want %q", cfg.ClientID, "nix-cache-server")
+	}
+}
+
 func contains(s, substr string) bool {
 	return len(s) >= len(substr) && searchString(s, substr)
 }