Convert from a Standalone Repository to a Monorepo

You can always add another app to a standalone repository the same way you would in a monorepo. But at some point, you may want to move the primary app out of the root of your repo because the repo is no longer primarily focused on that one app. There are other apps that are equally important and you want the folder structure to align with the new reality.

Run the Generator

The convert-to-monorepo generator will attempt to convert a standalone repo to a monorepo.

nx g convert-to-monorepo

If you need to do the conversion manually, you can follow the steps below.

Manual Conversion Strategy

For this recipe, we'll assume that the root-level app is named my-app. The high-level process we'll go through to move the app involves four stages:

1. Create a new app named temp under apps/temp.
2. Move source and config files from my-app into apps/temp.
3. Delete the files for my-app.
4. Rename apps/temp to apps/my-app

Steps

1. If there is a tsconfig.json file in the root, rename it to tsconfig.old.json

   This step is to make sure that a tsconfig.base.json file is generated by the app generator in the next step.

2. Create a new app using the appropriate plugin under apps/temp

   nx g app apps/temp

3. Move the /src (and /public, if present) folders to apps/temp/, overwriting the folders already there.

4. For each config file in apps/temp, copy over the corresponding file from the root of the repo.

   It can be difficult to know which files are root-level config files and which files are project-specific config files. Here is a non-exhaustive list of config files to help distinguish between the two.

   Type of Config	Files
   Root-level	.eslintignore, .eslintrc.base.json, .gitignore, .prettierignore, jest.config.ts, jest.preset.js, .prettierrc, nx.json, package.json, tsconfig.base.json
   Project-level	.eslintrc.json, index.html, project.json, jest.config.app.ts, tsconfig.app.json, tsconfig.json, tsconfig.spec.json, vite.config.ts, webpack.config.js

   jest.config.app.ts

   jest.config.app.ts in the root should be renamed to jest.config.ts when moved to apps/temp. Also update the jestConfig option in project.json to point to jest.config.ts instead of jest.config.app.ts.

5. Update the paths of the project-specific config files that were copied into apps/temp.

   Here is a non-exhaustive list of properties that will need to be updated to have the correct path:

   Config File(s)	Properties to Check
   project.json	$schema, sourceRoot, root, outputPath, reportsDirectory, cypressConfig, lintFilePatterns, index, main, tsConfig, assets, styles, jestConfig
   tsconfig.json, tsconfig.app.json, tsconfig.spec.json	extends, outDir, files
   .eslintrc.json	extends
   jest.config.ts	preset, coverageDirectory
   vite.config.ts	cacheDir, root, dir

6. Doublecheck that all the tasks defined in the apps/temp/project.json file still work.

   nx build temp
   nx test temp
   nx lint temp

7. Move the /e2e/src folder to /apps/temp-e2e, overwriting the folder already there

8. For each config file in apps/temp-e2e, copy over the corresponding file from the root of the repo. Update the paths for these files in the same way you did for the my-app config files.

9. Update the /apps/temp-e2e/project.json implicitDependencies to be temp instead of my-app

10. Doublecheck that all the tasks defined in the apps/temp-e2e/project.json file still work.

    nx lint temp-e2e
    nx e2e temp-e2e

11. Delete all the project specific config files in the root and under e2e

12. Once the project.json file has been deleted in the root, rename temp-e2e to my-app-e2e and rename temp to my-app

    nx g move --projectName=temp-e2e --destination=my-app-e2e
    nx g move --projectName=temp --destination=my-app

13. Update the defaultProject in nx.json if needed

14. Check again that all the tasks still work and that the nx graph displays what you expect.