Multisite compatibility

[vever001]

Hi,

We inherited a D8 multisite a few months ago (ECDC project).
ATM I have made some workarounds to be able to work on it using the task-runner and the toolkit but it is far from optimal.
Ideally, we should make both the task-runner and the toolkit multisite-compatible.
This is I think a big task so perhaps some of you have ideas or plans already?

Here are some things I have in mind:

1. I think we should first make the task-runner multisite-compatible so that we can run it with aliases (e.g: ./vendor/bin/run @myalias command:name)
   I investigated the possibility to use SiteAlias (used by drush) but that would require a lot of changes.
   Another simpler approach is to do something similar to what Drupal Console does.
2. I noticed a lot of commands in the toolkit are spawning new processes (./vendor/bin/run ...) which makes it loose the current context (e.g: the alias or options passed in the first command).
   This could be solved in a similar way to BLT which defines an invokeCommands() method: https://github.com/acquia/blt/blob/12.x/src/Robo/BltTasks.php#L53

[vever001]

1. I made a very rough POC here https://github.com/vever001/task-runner/tree/multisite-support based on Acquia BLT.
   Still needs a lot of work to be even usable but it's a start.
2. Point 2 still needs to be implemented to make it truly usable with the NE toolkit, which itself, would also need a lot of changes as well.
   The approach from BLT (https://github.com/acquia/blt/blob/12.x/src/Robo/BltTasks.php#L53) works but cannot be implemented within a task since we do not have access to the container or application.
   There's also Allow commands to call other commands consolidation/annotated-command#64 (comment)