Upgrade to Drush 9 or remove it entirely?

[jacine]

We're currently limiting to Drush to version 8, due to lack of sufficient Pantheon support. This made sense while Pantheon support was in flux, but since that is done, and they've got their own repository for this, we don't need to do that anymore.

We should consider upgrading or removing Drush, and adding a note for Pantheon users to either:

• Remove site-local (composer-installed) Drush, which is what Pantheon recommends:
  composer remove drush/drush
• Or, use Drush 8:
  composer require drush/drush:~8

[cnovak]

I just ran into this issue myself, the Drush commands of the Key module act different between Drush 8 & 9. I don't think there is an issue running Drush 9 since I put up a drupal-composer/drupal-project which includes Drush 9 and there are no issues. Drupal 8 recommends having a Drush version in your composer file, so it would be tough to not have Drush installed locally for the project when you are working locally.

To test this, I put up a Kickstart site on Pantheon using my Installing Apigee Kickstart on Pantheon.io instructions.

I can then make the following call to see the Drush 8 is running:

 $ terminus remote:drush kickstart.dev -- --version
 Drush Version   :  8.3.0 

I then updated my composer.json to have Drush 9 instead just like drupal-composer/drupal-project:

"drush/drush": "^9.0.0"

Drush version is now 9:

 $ terminus remote:drush kickstart.dev -- --version
Drush Commandline Tool 9.7.1

I also added a comment to the Terminus issue that that talks about Drush 9 issues on Pantheon](pantheon-systems/terminus#1849 (comment)) to see if Drush 9 is still an issue on Pantheon.io.

[arunz6161]

To be discussed in tech meet - 08/12

[cnovak]

Got response back from Pantheon.io that Drush 9 works! Looks like we can add Drupal 9 to the repo.

[shadcn]

We were blocked with subtheming and Drush 9. But Radix is now compatible with Drush 9. I'll create a new release and we can update this.

[jacine]

@cnovak Great! It's nice to see that Pantheon is finally in a state to actually support Drush 9. I feel like we have been waiting for Drush 9 forever. At the time of your comment there was still a big piece missing (aliases), but that has been since merged, so I'm good with whatever we decide here.

Sounds like you would prefer to include Drush 9, as opposed to removing it (which is what Arshad's PR does), right? In that case we will need an a new/updated PR.

[arlina-espinoza]

@jacine Yes, an update to use Drush 9 is what is needed. Thanks :)

[jacine]

Thanks @arlina-espinoza. Here's a PR: #18.