Automate Updating Dependencies

Keeping a codebase updated with the latest changes in your framework of choice can be challenging. Not to mention that "tooling maintenance work" is usually hard to squeeze into your feature sprint.

The nx migrate command helps by automating the process of updating:

• package versions in your package.json
• configuration files (e.g. your Jest, ESLint or Nx config)
• your source code (e.g. fixing breaking changes or migrating to new best practices)

How does it work?

Nx knows where its configuration files are and can therefore make sure they match the expected format. This automated update process, commonly referred to as "migration," becomes even more powerful when you leverage Nx plugins. Nx plugins, which are NPM packages with a range of capabilities (code generation, task automation...), offer targeted updates based on their specific areas of responsibility.

For example, the Nx ESLint plugin excels at configuring linting in your workspace. With its understanding of the configuration file locations, this plugin can provide precise migration scripts to update ESLint packages in your package.json and corresponding configuration files in your workspace when a new version is released.

Updating happens in three steps:

• The installed dependencies are updated including the package.json (and node_modules).
• The source code in the repo is updated to match the new versions of packages according to the set of instructions specified in migrations.json file.
• Optionally remove the migrations.json file or keep it to re-run the migration in different Git branches

Step 1: Updating dependencies and generating migrations

First, run the migrate command:

Note you can also specify an exact version by replacing latest with nx@<version>.

This fetches the specified version of the nx package, analyzes the dependencies and fetches all the dependent packages. The process keeps going until all the dependencies are resolved. This results in:

• The package.json being updated
• A migrations.json being generated if there are pending migrations.

At this point, no packages have been installed, and no other files have been touched.

Now, you can inspect package.json to see if the changes make sense. Sometimes the migration can update a package to a version that is either not allowed or conflicts with another package. Feel free to manually apply the desired adjustments.

Step 2: Running migrations

You can now run the actual code migrations that were generated in the migrations.json in the previous step.

This will update your source code in your workspace in accordance with the implementation of the various migrations which ran and all the changes will be unstaged ready for you to review and commit yourself.

Note that each Nx plugin is able to provide a set of migrations which are relevant to particular versions of the package. Hence migrations.json will only contain migrations which are appropriate for the update you are currently applying.

Step 3: Cleaning up

After you run all the migrations, you can remove migrations.json and commit any outstanding changes.

Note: You may want to keep the migrations.json until every branch that was created before the migration has been merged. Leaving the migrations.json in place allows devs to run nx migrate --run-migrations to apply the same migration process to their newly merged code as well.

Need to opt-out of some migrations?

Sometimes you need to temporarily opt-out from some migrations because your workspace is not ready yet. You can manually adjust the migrations.json or run the update with the --interactive flag to choose which migrations you accept. Find more details in our Advanced Update Process guide.