Support loading alertmanager template files in different directories

CHANGELOG.md

@@ -7,6 +7,7 @@ Order should be `CHANGE`, `FEATURE`, `ENHANCEMENT`, and `BUGFIX`
 * [CHANGE] Updates version of Go to 1.22 and Alpine to 3.19.1 in Dockerfiles
 * [FEATURE] Make rulerAPI Path configurable
 * [FEATURE] Add tool to deserialize alertmanager state file
+* [ENHANCEMENT] Support loading alertmanager templates from different directories
 * [BUGFIX] Set tenant id in prom analyse command
 
 ## v0.11.1

pkg/commands/alerts.go

@@ -8,6 +8,7 @@ import (
 	"net/http"
 	"os"
 	"os/signal"
+	"path/filepath"
 	"strings"
 	"time"
 
@@ -120,16 +121,29 @@ func (a *AlertmanagerCommand) loadConfig(_ *kingpin.ParseContext) error {
 		return err
 	}
 
-	templates := map[string]string{}
-	for _, f := range a.TemplateFiles {
+	templates, err := createTemplates(a.TemplateFiles)
+	if err != nil {
+		return err
+	}
+
+	return a.cli.CreateAlertmanagerConfig(context.Background(), cfg, templates)
+}
+
+func createTemplates(templateFiles []string) (map[string]string, error) {
+	templates := make(map[string]string)
+	for _, f := range templateFiles {
 		tmpl, err := os.ReadFile(f)
 		if err != nil {
-			return errors.Wrap(err, "unable to load template file: "+f)
+			return nil, errors.Wrap(err, "unable to load template file: "+f)
 		}
-		templates[f] = string(tmpl)
-	}
 
-	return a.cli.CreateAlertmanagerConfig(context.Background(), cfg, templates)
+		baseName := filepath.Base(f)
+		if _, ok := templates[baseName]; ok {
+			return nil, fmt.Errorf("duplicate template file name: %s", baseName)
+		}
+		templates[baseName] = string(tmpl)
+	}
+	return templates, nil
 }
 
 func (a *AlertmanagerCommand) deleteConfig(_ *kingpin.ParseContext) error {

pkg/commands/alerts_test.go

@@ -0,0 +1,76 @@
+package commands
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestCreateTemplates(t *testing.T) {
+	// Create a temporary file
+	tmpfile, err := os.CreateTemp("", "template")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(tmpfile.Name()) // clean up
+
+	// Write some data to the file
+	text := "This is a test template"
+	if _, err := tmpfile.Write([]byte(text)); err != nil {
+		t.Fatal(err)
+	}
+	if err := tmpfile.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	// Call createTemplates
+	templates, err := createTemplates([]string{tmpfile.Name()})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Check the returned map
+	if len(templates) != 1 {
+		t.Fatalf("Expected 1 template, got %d", len(templates))
+	}
+	if templates[filepath.Base(tmpfile.Name())] != text {
+		t.Fatalf("Expected template content to be '%s', got '%s'", text, templates[filepath.Base(tmpfile.Name())])
+	}
+}
+
+func TestCreateTemplates_DuplicateFilenames(t *testing.T) {
+	// Create two temporary files with the same base name in different directories
+	dir1 := filepath.Join(os.TempDir(), "dir1")
+	if err := os.Mkdir(dir1, 0755); err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(dir1) // clean up
+	tmpfile1, err := os.Create(filepath.Join(os.TempDir(), "dir1", "fool.tmpl"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(tmpfile1.Name()) // clean up
+
+	dir2 := filepath.Join(os.TempDir(), "dir2")
+	if err := os.Mkdir(dir2, 0755); err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(dir2) // clean up
+	tmpfile2, err := os.Create(filepath.Join(os.TempDir(), "dir2", "fool.tmpl"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(tmpfile2.Name()) // clean up
+
+	// Call createTemplates
+	_, err = createTemplates([]string{tmpfile1.Name(), tmpfile2.Name()})
+	if err == nil {
+		t.Fatal("Expected error due to duplicate filenames, got nil")
+	}
+
+	// Check that the error message contains "duplicate template file name"
+	if !strings.Contains(err.Error(), "duplicate template file name") {
+		t.Fatalf("Expected error message to contain 'duplicate template file name', got '%s'", err.Error())
+	}
+}