overrides

internal/kubezones/client.go

@@ -42,6 +42,16 @@ type Client struct {
 // InCluster returns nil outside Kubernetes. The projected service account
 // token must be available; RBAC limits it to the fancy-dns-zones ConfigMap.
 func InCluster() (*Client, error) {
+	name := os.Getenv("FANCYDNS_ZONE_CONFIGMAP")
+	if name == "" {
+		name = defaultName
+	}
+	return InClusterConfigMap(name)
+}
+
+// InClusterConfigMap returns a client for a named ConfigMap. RBAC on the
+// service account still limits which ConfigMaps it can read or patch.
+func InClusterConfigMap(name string) (*Client, error) {
 	host := os.Getenv("KUBERNETES_SERVICE_HOST")
 	if host == "" {
 		return nil, nil
@@ -69,9 +79,8 @@ func InCluster() (*Client, error) {
 	if !pool.AppendCertsFromPEM(ca) {
 		return nil, errors.New("kube zones: invalid service account CA")
 	}
-	name := os.Getenv("FANCYDNS_ZONE_CONFIGMAP")
-	if name == "" {
-		name = defaultName
+	if strings.TrimSpace(name) == "" {
+		return nil, errors.New("kube zones: ConfigMap name is required")
 	}
 	return &Client{
 		baseURL: "https://" + net.JoinHostPort(host, port),
@@ -119,14 +128,47 @@ func (c *Client) Delete(ctx context.Context, name string) error {
 	return c.change(ctx, filename(name), nil)
 }
 
+// Data reads one arbitrary ConfigMap data key. It is used for console-owned
+// shared files that are not zone master files.
+func (c *Client) Data(ctx context.Context, key string) (string, bool, error) {
+	if c == nil {
+		return "", false, errors.New("kube zones: Kubernetes ConfigMap is unavailable")
+	}
+	cm, _, err := c.get(ctx)
+	if err != nil {
+		return "", false, err
+	}
+	value, ok := cm.Data[key]
+	return value, ok, nil
+}
+
+// SaveData creates or replaces one arbitrary ConfigMap data key, retrying
+// resource-version conflicts so independent edits to different keys merge.
+func (c *Client) SaveData(ctx context.Context, key, content string) error {
+	if c == nil {
+		return errors.New("kube zones: Kubernetes ConfigMap is unavailable")
+	}
+	if key == "" || len(key) > 253 || strings.ContainsAny(key, `/\\`) {
+		return errors.New("kube zones: invalid ConfigMap data key")
+	}
+	if len(content) > 512*1024 {
+		return errors.New("kube zones: ConfigMap data exceeds 512 KiB")
+	}
+	return c.changeData(ctx, key, &content)
+}
+
 func filename(name string) string { return "zone--" + strings.TrimSuffix(name, ".") + ".zone" }
 
 func (c *Client) change(ctx context.Context, name string, content *string) error {
 	if !validKey(name) {
 		return errors.New("zone filename must be a DNS name ending in .zone")
 	}
+	return c.changeData(ctx, name, content)
+}
+
+func (c *Client) changeData(ctx context.Context, name string, content *string) error {
 	if content != nil && len(*content) > 512*1024 {
-		return errors.New("zone file exceeds 512 KiB")
+		return errors.New("ConfigMap data exceeds 512 KiB")
 	}
 	for attempt := 0; attempt < 3; attempt++ {
 		_, rv, err := c.get(ctx)