feat(create): better detection of package manager preference (#6679)

Co-authored-by: sebastienlorber <lorber.sebastien@gmail.com>

packages/create-docusaurus/src/index.ts

@@ -17,12 +17,56 @@ import {fileURLToPath} from 'url';
 const RecommendedTemplate = 'classic';
 const TypeScriptTemplateSuffix = '-typescript';
 
-function hasYarn() {
-  try {
-    return shell.exec('yarnpkg --version', {silent: true}).code === 0;
-  } catch (e) {
-    return false;
+const DefaultPackageManager = 'npm';
+
+const SupportedPackageManagers = {
+  npm: 'package-lock.json',
+  yarn: 'yarn.lock',
+  pnpm: 'pnpm-lock.yaml',
+};
+
+type SupportedPackageManager = keyof typeof SupportedPackageManagers;
+
+const PackageManagersList = Object.keys(
+  SupportedPackageManagers,
+) as SupportedPackageManager[];
+
+async function findPackageManagerFromLockFile(): Promise<
+  SupportedPackageManager | undefined
+> {
+  for (const packageManager of PackageManagersList) {
+    const lockFilePath = path.resolve(
+      process.cwd(),
+      SupportedPackageManagers[packageManager],
+    );
+    if (await fs.pathExists(lockFilePath)) {
+      return packageManager;
+    }
   }
+  return undefined;
+}
+
+function findPackageManagerFromUserAgent():
+  | SupportedPackageManager
+  | undefined {
+  return PackageManagersList.find((packageManager) =>
+    process.env.npm_config_user_agent?.startsWith(packageManager),
+  );
+}
+
+async function getPackageManager(
+  forceUseNpm?: boolean,
+): Promise<SupportedPackageManager> {
+  // TODO replace --use-npm by --package-manager option
+  if (forceUseNpm) {
+    return 'npm';
+  }
+
+  return (
+    (await findPackageManagerFromLockFile()) ??
+    findPackageManagerFromUserAgent() ??
+    DefaultPackageManager
+  );
 }
 
 function isValidGitRepoUrl(gitRepoUrl: string) {
@@ -131,14 +175,13 @@ export default async function init(
     gitStrategy: typeof gitStrategies[number];
   }> = {},
 ): Promise<void> {
-  const useYarn = cliOptions.useNpm ? false : hasYarn();
+  const pkgManager = await getPackageManager(cliOptions.useNpm);
   const templatesDir = fileURLToPath(new URL('../templates', import.meta.url));
   const templates = await readTemplates(templatesDir);
   const hasTS = (templateName: string) =>
     fs.pathExists(
       path.resolve(templatesDir, `${templateName}${TypeScriptTemplateSuffix}`),
     );
-
   let name = siteName;
 
   // Prompt if siteName is not passed from CLI.
@@ -313,21 +356,23 @@ export default async function init(
     await fs.remove(path.join(dest, 'gitignore'));
   }
 
-  const pkgManager = useYarn ? 'yarn' : 'npm';
   // Display the most elegant way to cd.
   const cdpath = path.relative('.', dest);
   if (!cliOptions.skipInstall) {
     shell.cd(dest);
     logger.info`Installing dependencies with name=${pkgManager}...`;
     if (
-      shell.exec(useYarn ? 'yarn' : 'npm install --color always', {
-        env: {
-          ...process.env,
-          // Force coloring the output, since the command is invoked by shelljs,
-          // which is not the interactive shell
-          ...(supportsColor.stdout ? {FORCE_COLOR: '1'} : {}),
+      shell.exec(
+        pkgManager === 'yarn' ? 'yarn' : `${pkgManager} install --color always`,
+        {
+          env: {
+            ...process.env,
+            // Force coloring the output, since the command is invoked,
+            // by shelljs which is not the interactive shell
+            ...(supportsColor.stdout ? {FORCE_COLOR: '1'} : {}),
+          },
         },
-      }).code !== 0
+      ).code !== 0
     ) {
       logger.error('Dependency installation failed.');
       logger.info`The site directory has already been created, and you can retry by typing:
@@ -338,16 +383,17 @@ export default async function init(
     }
   }
 
+  const useNpm = pkgManager === 'npm';
   logger.success`Created path=${cdpath}.`;
   logger.info`Inside that directory, you can run several commands:
 
   code=${`${pkgManager} start`}
     Starts the development server.
 
-  code=${`${pkgManager} ${useYarn ? '' : 'run '}build`}
+  code=${`${pkgManager} ${useNpm ? 'run ' : ''}build`}
     Bundles your website into static files for production.
 
-  code=${`${pkgManager} ${useYarn ? '' : 'run '}serve`}
+  code=${`${pkgManager} ${useNpm ? 'run ' : ''}serve`}
     Serves the built website locally.
 
   code=${`${pkgManager} deploy`}