Allow specifying target container for hook execution

[codemonkey1988]

Is your feature request related to a problem? Please describe.
When you want to execute a hook in different container than the web container, you currently need to use the exec-host command an run ddev exec -s my-service my-command.

Describe the solution you'd like
It would be nice, if you could somehow specify the target container for the hook to execute.
One possible solution could be integrating the services name into the exec command.

Example:
When you got a service named node you can execute a hook in it by using exec-node. This solution would keep the current syntax. exec-host would stay as be special keyword and only exec would be the same as exec-web (it it might be an alias for compatibility.

The whole hook config could look like this:

hooks:
  post-start:
    exec: composer install -d /var/www/html
    exec-node: npm install

[rfay]

I think this is long-neglected but a really valid application. I wish our existing config language had a spot for the container name. It really allow something like:

hooks:
  post-start:
    exec:
      container: db
      command: mysql --version

[andrewfrench]

This seems like a natural progression as people increasingly use custom containers, and I'd imagine there are some use cases for executing hooks on our existing non-web containers now.

On the back end, we already support exec-ing commands on arbitrary containers, but we'll need to decide on the front-end parsing and error handling specifics.

[codemonkey1988]

@rfay Your solution would be the better one I think, but it would also be a breaking change for many people unless you keep the current syntax for compatibility. I don't know how you will handle breaking changes in stable releases, but this might annoy people when they have to update all their ddev projects with hooks.

[kristoftorfs]

@codemonkey1988 To be honest, I don't think keeping this backwards compatible is that hard. If the exec node is a string it's defined in the old way, if it's a hash it's the new way.

Is there any progress made on this? I literally have zero projects where I don't use custom services and this would be a major improvement.

[rfay]

Thanks for chiming in on this @kristoftorfs - Just an FYI about workarounds you probably already use... If the web container has access to the other service, then hooks can be executed against the web container and take action against another container. For example, since the web container has mysql access to the db container, you can add a hook that does a mysql command.

This would likely be a part of #1372, which is about the hook system in general.