Add support for local catalog via command-line flags (#10)

Author: SheryarButt

README.md

@@ -75,6 +75,8 @@ The downloaded binary is named `{tool}_{version}-{os}_{arch}`, for example:
 | `--username` | `-u` | Registry username |
 | `--password` | `-p` | Registry password |
 | `--verbose` | `-v` | Enable verbose logging |
+| `--catalog-url` | | URL of the tools catalog YAML (defaults to the catalog on this repository's `main` branch) |
+| `--catalog-file` | | Path to a local tools catalog YAML, instead of fetching `--catalog-url` |
 
 #### `get` command
 
@@ -88,7 +90,7 @@ The downloaded binary is named `{tool}_{version}-{os}_{arch}`, for example:
 
 ## Adding Tools
 
-Tools are defined in [`internal/tools/tools.yaml`](internal/tools/tools.yaml) and embedded into the binary at build time. To add a new tool, append an entry and rebuild:
+Tools are defined in [`internal/tools/tools.yaml`](internal/tools/tools.yaml), which is fetched at runtime from the `main` branch of this repository. To add a new tool, append an entry and open a pull request:
 
 ```yaml
 my-tool:
@@ -118,6 +120,22 @@ my-tool:
 
 The tag pulled from the registry is constructed as `{tag}-{os}_{arch}`, e.g. `latest-cli-linux_amd64`.
 
+### Using a Custom Catalog
+
+Both commands accept an alternative catalog, which is useful for testing an entry before it is merged, or for running fully offline:
+
+```bash
+# Local file
+kubermatic-ee-downloader list --catalog-file internal/tools/tools.yaml
+kubermatic-ee-downloader get my-tool --catalog-file ./my-catalog.yaml
+
+# Alternative URL (e.g. a branch or fork)
+kubermatic-ee-downloader list \
+  --catalog-url https://raw.githubusercontent.com/my-org/kubermatic-ee-downloader/my-branch/internal/tools/tools.yaml
+```
+
+`--catalog-file` and `--catalog-url` are mutually exclusive.
+
 ## Development
 
 ```bash

cmd/main.go

@@ -37,10 +37,11 @@ var version = "dev"
 
 func main() {
 	var (
-		username   string
-		password   string
-		verbose    bool
-		catalogURL string
+		username    string
+		password    string
+		verbose     bool
+		catalogURL  string
+		catalogFile string
 	)
 
 	rootCmd := &cobra.Command{
@@ -50,10 +51,20 @@ func main() {
 		SilenceUsage: true,
 		PersistentPreRunE: func(_ *cobra.Command, _ []string) error {
 			log := newLogger(verbose)
-			log.WithField("url", catalogURL).Debug("Fetching tool catalog")
-			catalog, err := tools.FetchCatalog(catalogURL, 5*time.Second)
+
+			var (
+				catalog map[string]tools.Tool
+				err     error
+			)
+			if catalogFile != "" {
+				log.WithField("file", catalogFile).Debug("Loading tool catalog from file")
+				catalog, err = tools.LoadCatalogFile(catalogFile)
+			} else {
+				log.WithField("url", catalogURL).Debug("Fetching tool catalog")
+				catalog, err = tools.FetchCatalog(catalogURL, 5*time.Second)
+			}
 			if err != nil {
-				return fmt.Errorf("load tool catalog: %w (use --catalog-url to specify an alternative)", err)
+				return fmt.Errorf("load tool catalog: %w (use --catalog-url or --catalog-file to specify an alternative)", err)
 			}
 			tools.KnownTools = catalog
 			return nil
@@ -64,6 +75,8 @@ func main() {
 	rootCmd.PersistentFlags().StringVarP(&password, "password", "p", "", "Registry password")
 	rootCmd.PersistentFlags().BoolVarP(&verbose, "verbose", "v", false, "Enable verbose logging")
 	rootCmd.PersistentFlags().StringVar(&catalogURL, "catalog-url", tools.DefaultCatalogURL, "URL of the tools catalog YAML")
+	rootCmd.PersistentFlags().StringVar(&catalogFile, "catalog-file", "", "Path to a local tools catalog YAML, instead of fetching --catalog-url")
+	rootCmd.MarkFlagsMutuallyExclusive("catalog-url", "catalog-file")
 
 	// --- list command ---
 	listCmd := &cobra.Command{

internal/tools/tools.go

@@ -19,6 +19,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"os"
 	"sort"
 	"time"
 
@@ -69,10 +70,27 @@ func FetchCatalog(url string, timeout time.Duration) (map[string]Tool, error) {
 		return nil, fmt.Errorf("reading catalog response: %w", err)
 	}
 
+	return parseCatalog(body)
+}
+
+// LoadCatalogFile reads and parses a tools catalog from a local file.
+func LoadCatalogFile(path string) (map[string]Tool, error) {
+	body, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("reading catalog file: %w", err)
+	}
+
+	return parseCatalog(body)
+}
+
+func parseCatalog(body []byte) (map[string]Tool, error) {
 	var m map[string]Tool
 	if err := yaml.Unmarshal(body, &m); err != nil {
 		return nil, fmt.Errorf("parsing catalog YAML: %w", err)
 	}
+	if len(m) == 0 {
+		return nil, fmt.Errorf("catalog contains no tools")
+	}
 
 	return m, nil
 }

internal/tools/tools_test.go

@@ -20,6 +20,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"os"
+	"path/filepath"
 	"testing"
 	"time"
 )
@@ -144,6 +145,58 @@ test-tool:
 	}
 }
 
+func TestFetchCatalogEmpty(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte("---\n"))
+	}))
+	defer srv.Close()
+
+	_, err := FetchCatalog(srv.URL, 5*time.Second)
+	if err == nil {
+		t.Fatal("expected error for empty catalog")
+	}
+}
+
+func TestLoadCatalogFileSuccess(t *testing.T) {
+	catalog, err := LoadCatalogFile("tools.yaml")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if _, ok := catalog["conformance-tester"]; !ok {
+		t.Error("expected conformance-tester in catalog")
+	}
+}
+
+func TestLoadCatalogFileErrors(t *testing.T) {
+	dir := t.TempDir()
+
+	invalid := filepath.Join(dir, "invalid.yaml")
+	if err := os.WriteFile(invalid, []byte("not: valid: yaml: ["), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	empty := filepath.Join(dir, "empty.yaml")
+	if err := os.WriteFile(empty, nil, 0o600); err != nil {
+		t.Fatal(err)
+	}
+
+	tests := []struct {
+		name string
+		path string
+	}{
+		{name: "missing file", path: filepath.Join(dir, "does-not-exist.yaml")},
+		{name: "invalid YAML", path: invalid},
+		{name: "empty file", path: empty},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if _, err := LoadCatalogFile(tt.path); err == nil {
+				t.Fatalf("expected error for %s", tt.name)
+			}
+		})
+	}
+}
+
 func TestFetchCatalogNonOKStatus(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusNotFound)