cli: added config:docs command

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

.changeset/fair-carrots-tell.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+Add `config:docs` command that opens up reference documentation for the local configuration schema in a browser.

packages/cli/src/commands/config/docs.ts

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2021 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.
+ */
+
+import { JsonObject } from '@backstage/config';
+import { mergeConfigSchemas } from '@backstage/config-loader';
+import { Command } from 'commander';
+import { JSONSchema7 as JSONSchema } from 'json-schema';
+import openBrowser from 'react-dev-utils/openBrowser';
+import { loadCliConfig } from '../../lib/config';
+
+const DOCS_URL = 'https://config.backstage.io';
+
+export default async (cmd: Command) => {
+  const { schema: appSchemas } = await loadCliConfig({
+    args: [],
+    fromPackage: cmd.package,
+    mockEnv: true,
+  });
+
+  const schema = mergeConfigSchemas(
+    (appSchemas.serialize().schemas as JsonObject[]).map(
+      _ => _.value as JSONSchema,
+    ),
+  );
+
+  openBrowser(`${DOCS_URL}#schema=${JSON.stringify(schema)}`);
+};

packages/cli/src/commands/index.ts

@@ -140,6 +140,15 @@ export function registerCommands(program: CommanderStatic) {
     .description('Run tests, forwarding args to Jest, defaulting to watch mode')
     .action(lazy(() => import('./testCommand').then(m => m.default)));
 
+  program
+    .command('config:docs')
+    .option(
+      '--package <name>',
+      'Only include the schema that applies to the given package',
+    )
+    .description('Browse the configuration reference documentation')
+    .action(lazy(() => import('./config/docs').then(m => m.default)));
+
   program
     .command('config:print')
     .option(