Core¶

The project root is a normal core git checkout. The overlay never modifies core's composer.json or composer.lock, so you work on core as usual: edit files, run tests, commit, push and create patches.

Switching core branches¶

Another core branch can have a different composer.json, so the overlay needs a fresh solve after a switch. ddev switch does both:

ddev switch core 11.x

This runs git switch, waits for the container to see the new files, and runs ddev composer update. The same thing by hand is git switch 11.x && ddev composer update.

--pull fetches the branch and fast-forwards it first, so Composer resolves against the code that is on drupal.org today rather than whatever your last checkout left behind:

ddev switch --pull core 11.x

The branch is only fast-forwarded. If yours and the remote's have diverged, the checkout stays where it is, with a note on how to see what differs, and the Composer update still runs.

ddev switch only switches to branches you have already fetched, with or without --pull. For a branch that is new on drupal.org, run git fetch first.

Branches with the same name on several remotes¶

A branch that doesn't exist locally yet is created from the drupal.org repository. Issue fork remotes carry copies of the same branches, so a plain git switch 11.x fails with "matched multiple remote tracking branches" once you have fetched a few forks. ddev switch picks the drupal.org repository instead.

If none of the remotes with that branch is the drupal.org repository, it uses the remote set in git's checkout.defaultRemote, then origin. If that still leaves several, ddev switch lists them and asks you to choose with git switch --track <remote>/<branch>.

Distributions¶

core means whichever project is at the project root. The add-on reads it from the checkout's git remotes, so ddev switch core and ddev mr core also work on a distribution checkout.

Reproducing core's exact dependency versions¶

The overlay's dependencies are solved fresh, so shared packages like Symfony or Guzzle may resolve to newer versions than core's composer.lock. To reproduce a core bug or check a patch against the same versions core records, see Pinning core's locked versions.