cli: add migrate package-lint-configs command

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

packages/cli/src/commands/index.ts

@@ -165,6 +165,15 @@ export function registerMigrateCommand(program: CommanderStatic) {
     .action(
       lazy(() => import('./migrate/packageScripts').then(m => m.command)),
     );
+
+  command
+    .command('package-lint-configs')
+    .description(
+      'Migrates all packages to use @backstage/cli/config/eslint-factory',
+    )
+    .action(
+      lazy(() => import('./migrate/packageLintConfigs').then(m => m.command)),
+    );
 }
 
 export function registerCommands(program: CommanderStatic) {

packages/cli/src/commands/migrate/packageLintConfigs.ts

@@ -0,0 +1,89 @@
+/*
+ * Copyright 2020 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.
+ */
+
+import fs from 'fs-extra';
+import { resolve as resolvePath } from 'path';
+import { PackageGraph } from '../../lib/monorepo';
+import { runPlain } from '../../lib/run';
+
+const PREFIX = `module.exports = require('@backstage/cli/config/eslint-factory')`;
+
+export async function command() {
+  const packages = await PackageGraph.listTargetPackages();
+
+  const oldConfigs = [
+    require.resolve('@backstage/cli/config/eslint.js'),
+    require.resolve('@backstage/cli/config/eslint.backend.js'),
+  ];
+
+  const configPaths = new Array<string>();
+  await Promise.all(
+    packages.map(async ({ dir, packageJson }) => {
+      const configPath = resolvePath(dir, '.eslintrc.js');
+      if (!(await fs.pathExists(configPath))) {
+        console.log(`Skipping ${packageJson.name}, missing .eslintrc.js`);
+        return;
+      }
+      let existingConfig: Record<string, unknown>;
+      try {
+        existingConfig = require(configPath);
+      } catch (error) {
+        console.log(
+          `Skipping ${packageJson.name}, failed to load .eslintrc.js, ${error}`,
+        );
+        return;
+      }
+
+      // Only transform configs that extend the old config files, and
+      // we remove that entry from the extends array.
+      const extendsArray = (existingConfig.extends as string[]) ?? [];
+      const extendIndex = extendsArray.findIndex(p => oldConfigs.includes(p));
+      if (extendIndex === -1) {
+        console.log(
+          `Skipping ${packageJson.name}, .eslintrc.js does not extend the legacy config`,
+        );
+        return;
+      }
+      extendsArray.splice(extendIndex, 1);
+      if (extendsArray.length === 0) {
+        delete existingConfig.extends;
+      }
+
+      if (Object.keys(existingConfig).length > 0) {
+        await fs.writeFile(
+          configPath,
+          `${PREFIX}(__dirname, ${JSON.stringify(existingConfig, null, 2)});\n`,
+        );
+      } else {
+        await fs.writeFile(configPath, `${PREFIX}(__dirname);\n`);
+      }
+      configPaths.push(configPath);
+    }),
+  );
+
+  // If prettier is present, then we run that too
+  let hasPrettier = false;
+  try {
+    require.resolve('prettier');
+    hasPrettier = true;
+  } catch {
+    /* ignore */
+  }
+
+  if (hasPrettier) {
+    await runPlain('prettier', '--write', ...configPaths);
+  }
+}