Remote Alertmanager(refactor): Only parse the URL once (#78631)

* Remote Alertmanager(refactor): Only parse the URL once

Exactly what it says in the tin.

Signed-off-by: gotjosh <josue.abreu@gmail.com>

* use the existing tests

Signed-off-by: gotjosh <josue.abreu@gmail.com>

---------

Signed-off-by: gotjosh <josue.abreu@gmail.com>

pkg/services/ngalert/remote/alertmanager.go

@@ -55,13 +55,18 @@ func NewAlertmanager(cfg AlertmanagerConfig, orgID int64) (*Alertmanager, error)
 	}
 
 	if cfg.URL == "" {
-		return nil, fmt.Errorf("empty URL for tenant %s", cfg.TenantID)
+		return nil, fmt.Errorf("empty remote Alertmanager URL for tenant '%s'", cfg.TenantID)
+	}
+
+	u, err := url.Parse(cfg.URL)
+	if err != nil {
+		return nil, fmt.Errorf("unable to parse remote Alertmanager URL: %w", err)
 	}
 
 	logger := log.New("ngalert.remote.alertmanager")
 
 	mcCfg := &mimirClient.Config{
-		Address:  cfg.URL,
+		URL:      u,
 		TenantID: cfg.TenantID,
 		Password: cfg.BasicAuthPassword,
 		Logger:   logger,
@@ -72,11 +77,6 @@ func NewAlertmanager(cfg AlertmanagerConfig, orgID int64) (*Alertmanager, error)
 		return nil, err
 	}
 
-	u, err := url.Parse(cfg.URL)
-	if err != nil {
-		return nil, err
-	}
-
 	u = u.JoinPath("/alertmanager", amclient.DefaultBasePath)
 	transport := httptransport.NewWithClient(u.Host, u.Path, []string{u.Scheme}, &client)
 

pkg/services/ngalert/remote/alertmanager_test.go

@@ -37,7 +37,15 @@ func TestNewAlertmanager(t *testing.T) {
 			tenantID: "1234",
 			password: "test",
 			orgID:    1,
-			expErr:   "empty URL for tenant 1234",
+			expErr:   "empty remote Alertmanager URL for tenant '1234'",
+		},
+		{
+			name:     "invalid URL",
+			url:      "asdasd%sasdsd",
+			tenantID: "1234",
+			password: "test",
+			orgID:    1,
+			expErr:   "unable to parse remote Alertmanager URL: parse \"asdasd%sasdsd\": invalid URL escape \"%sa\"",
 		},
 		{
 			name:     "valid parameters",

pkg/services/ngalert/remote/client/mimir.go

@@ -32,7 +32,7 @@ type Mimir struct {
 }
 
 type Config struct {
-	Address  string
+	URL      *url.URL
 	TenantID string
 	Password string
 
@@ -61,11 +61,6 @@ func (e *errorResponse) Error() string {
 }
 
 func New(cfg *Config) (*Mimir, error) {
-	endpoint, err := url.Parse(cfg.Address)
-	if err != nil {
-		return nil, err
-	}
-
 	rt := &MimirAuthRoundTripper{
 		TenantID: cfg.TenantID,
 		Password: cfg.Password,
@@ -77,7 +72,7 @@ func New(cfg *Config) (*Mimir, error) {
 	}
 
 	return &Mimir{
-		endpoint: endpoint,
+		endpoint: cfg.URL,
 		client:   c,
 		logger:   cfg.Logger,
 	}, nil