Add a configuration schema for the proxy plugin

.changeset/weak-roses-search.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-proxy-backend': patch
+---
+
+Add configuration schema for the commonly used properties

app-config.yaml

@@ -38,7 +38,7 @@ proxy:
     headers:
       Authorization:
         $env: TRAVISCI_AUTH_TOKEN
-      travis-api-version: 3
+      travis-api-version: '3'
 
   '/newrelic/apm/api':
     target: https://api.newrelic.com/v2

plugins/proxy-backend/config.d.ts

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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 {
+  /**
+   * A list of forwarding-proxies. Each key is a route to match,
+   * below the prefix that the proxy plugin is mounted on. I must
+   * start with a '/'.
+   */
+  proxy: { [key: string]: string | ProxyConfig };
+}
+
+interface ProxyConfig {
+  /**
+   * Target of the proxy. Url string to be parsed with the url module.
+   */
+  target: string;
+  /**
+   * Object with extra headers to be added to target requests.
+   */
+  headers?: { [key: string]: string };
+  /**
+   * Changes the origin of the host header to the target URL. Default: true.
+   */
+  changeOrigin?: boolean;
+  /**
+   * Rewrite target's url path. Object-keys will be used as RegExp to match paths.
+   * If pathRewrite is not specified, it is set to a single rewrite that removes the entire prefix and route.
+   */
+  pathRewrite?: { [regexp: string]: string };
+  /**
+   * Limit the forwarded HTTP methods, for example allowedMethods: ['GET'] to enforce read-only access.
+   */
+  allowedMethods?: string[];
+  /**
+   * Limit the forwarded HTTP methods. By default, only the headers that are considered safe for CORS
+   * and headers that are set by the proxy will be forwarded.
+   */
+  allowedHeaders?: string[];
+}

plugins/proxy-backend/package.json

@@ -41,6 +41,8 @@
     "supertest": "^4.0.2"
   },
   "files": [
-    "dist"
-  ]
+    "dist",
+    "config.d.ts"
+  ],
+  "configSchema": "config.d.ts"
 }