app-backend: migrate to use static configuration and extension point

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

plugins/app-backend/config.d.ts

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2023 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+export interface Config {
+  app?: {
+    /**
+     * The name of the app package (in most Backstage repositories, this is the
+     * "name" field in `packages/app/package.json`) that content should be served
+     * from. The same app package should be added as a dependency to the backend
+     * package in order for it to be accessible at runtime.
+     *
+     * In a typical setup with a single app package, this will default to 'app'.
+     */
+    packageName?: string;
+
+    /**
+     * Disables the configuration injection. This can be useful if you're running in an environment
+     * with a read-only filesystem, or for some other reason don't want configuration to be injected.
+     *
+     * Note that this will cause the configuration used when building the app bundle to be used, unless
+     * a separate configuration loading strategy is set up.
+     *
+     * This also disables configuration injection though `APP_CONFIG_` environment variables.
+     */
+    disableConfigInjection?: boolean;
+
+    /**
+     * By default the app backend plugin will cache previously deployed static assets in the database.
+     * If you disable this, it is recommended to set a `staticFallbackHandler` instead.
+     */
+    disableStaticFallbackCache?: boolean;
+  };
+}