Upgrading Drupal

The Polymer Drupal extension provides support for easing the Drupal upgrade process. This functionality is afforded by the drupal:upgrade command, which leverages the Drupal Core Composer Updater Plugin.

Upgrade process

The upgrade process happens in two phases:

1. The upgrade version is determined and the code is upgraded.
2. All sites run database updates and export configuration (if applicable).

Code upgrade

When you run the drupal:upgrade command, the configured upgrade strategy for the project is used. The extension defaults to the latest-minor strategy. The following strategies are available:

• latest-minor: Upgrades to the latest minor release of Drupal within the currently installed major version.
• next-major: Upgrades to the next major release of Drupal, relative to the current version installed.
• latest-major: Upgrades to the latest major release of Drupal.
• semantic: Upgrades your codebase relative to the specified versions constraints in your composer.json file (i.e. composer update).

If you run drupal:upgrade --new-version=..., then no upgrade strategy is used and instead that specific version of Drupal will be the targeted version upgraded to.

Database updates and configuration export

After the code upgrade is complete, all sites are updated and their configuration is exported (if applicable).

Finalizing the upgrade

Once the upgrade process has completed, you can add and commit all changes to a upgrade branch and create a pull request. It is of course recommended to put the upgrade changes through a QA process before merging the changes into your main line!