Experimental module warnings and Lightning

Lightning has used the Layout Plugin module since before our first beta release. Starting in Drupal 8.3.0, the functionality provided by the Layout Plugin module was largely duplicated in Layout Discovery and released as part of the Core Experimental group. Lightning migrated to Layout Discovery in 2.1.1.

The Lightning team feels like it's a win anytime we can migrate from contrib to core. But another advantage of this is that since Layout Discovery is in Core, security issues can be filed against it in the Core security issue queue which is monitored by the Security Team. Layout Plugin, being alpha, didn't have a security issue queue.

Technically, Layout Discovery is an Experimental core module though. And the new Status Report page warns users if any Experimental modules are enabled. As a result users of Lightning are presented with this unhelpful message when they visit /admin/reports/status:

The problem is, this message isn't actionable. Lightning made the decision to enable it. The only way to disable it would be to completely opt out of all of Lightning's Layout functionality.

To be clear, the Lightning team feels that the Layout Discovery module is certainly stable enough to run predictably and reliably on production websites. This warning from core is supposed to indicate that the underlying API might change or that it might ultimately be removed from the core package. Under either of those circumstances, Lightning would provide a migration script or otherwise support users.

We feel that warning a user after they (or their site builder) has made the decision to use an experimental module is in-actionable nagging. We support warning site builders when installing an experimental module, but not constantly reminding them of that decision.

Starting in 2.1.4, Lightning will include a core patch that removes the warnings for experimental modules on the status page. The patch does not affect the existing warning that is shown during installation of experimental modules.

There are two other "nagging" warnings that Lightning will remove in 2.1.4. Specifically, it will stop warning the user if:

Related, there is also a larger discussion around what the requirements should be for reporting on the status page. Discuss!

Summary of new patches related to reporting that will be included in 2.1.4:

• Remove scary 'experimental module' messages from appearing everywhere on the site (#2880374)
• Config sync should not throw a warning when not being writable (#2880445)
• Disable warning about update notifications (#2869592)