Alerting: Fix provisioned templates being ignored by alertmanager (#69485)

* Alerting: Fix provisioned templates being ignored by alertmanager

Template provisioning sets the template in cfg.TemplateFiles while a recent change
made it so that alertmanager reads cfg.AlertmanagerConfig.Templates instead.

This change fixes the issue on both ends, by having provisioning set boths fields and
reverts the change on the alertmanager side so that it uses cfg.TemplateFiles.

pkg/services/ngalert/notifier/alertmanager.go

@@ -260,13 +260,13 @@ func (am *Alertmanager) applyConfig(cfg *apimodels.PostableUserConfig, rawConfig
 		cfg.TemplateFiles = map[string]string{}
 	}
 	cfg.TemplateFiles["__default__.tmpl"] = alertingTemplates.DefaultTemplateString
-	cfg.AlertmanagerConfig.Templates = append(cfg.AlertmanagerConfig.Templates, "__default__.tmpl")
 
 	// next, we need to make sure we persist the templates to disk.
-	_, templatesChanged, err := PersistTemplates(am.logger, cfg, am.Base.WorkingDirectory())
+	paths, templatesChanged, err := PersistTemplates(am.logger, cfg, am.Base.WorkingDirectory())
 	if err != nil {
 		return false, err
 	}
+	cfg.AlertmanagerConfig.Templates = paths
 
 	// If neither the configuration nor templates have changed, we've got nothing to do.
 	if !amConfigChanged && !templatesChanged {

pkg/services/ngalert/notifier/config.go

@@ -32,7 +32,7 @@ func PersistTemplates(logger log.Logger, cfg *api.PostableUserConfig, path strin
 		}
 
 		file := filepath.Join(path, name)
-		pathSet[file] = struct{}{}
+		pathSet[name] = struct{}{}
 
 		// Check if the template file already exists and if it has changed
 		// We can safely ignore gosec here as we've previously checked the filename is clean
@@ -60,7 +60,7 @@ func PersistTemplates(logger log.Logger, cfg *api.PostableUserConfig, path strin
 	}
 	for _, existingFile := range existingFiles {
 		p := filepath.Join(path, existingFile.Name())
-		_, ok := pathSet[p]
+		_, ok := pathSet[existingFile.Name()]
 		if !ok {
 			templatesChanged = true
 			err := os.Remove(p)

pkg/services/ngalert/notifier/config_test.go

@@ -96,11 +96,6 @@ func TestPersistTemplates(t *testing.T) {
 				files[f.Name()] = string(content)
 			}
 
-			// Given we use a temporary directory in tests, we need to prepend the expected paths with it.
-			for i, p := range tt.expectedPaths {
-				tt.expectedPaths[i] = filepath.Join(dir, p)
-			}
-
 			require.Equal(t, tt.expectedError, persistErr)
 			require.ElementsMatch(t, tt.expectedPaths, paths)
 			require.Equal(t, tt.expectedChange, changed)

pkg/services/ngalert/provisioning/templates.go

@@ -53,6 +53,11 @@ func (t *TemplateService) SetTemplate(ctx context.Context, orgID int64, tmpl def
 		revision.cfg.TemplateFiles = map[string]string{}
 	}
 	revision.cfg.TemplateFiles[tmpl.Name] = tmpl.Template
+	tmpls := make([]string, 0, len(revision.cfg.TemplateFiles))
+	for name := range revision.cfg.TemplateFiles {
+		tmpls = append(tmpls, name)
+	}
+	revision.cfg.AlertmanagerConfig.Templates = tmpls
 
 	serialized, err := serializeAlertmanagerConfig(*revision.cfg)
 	if err != nil {