Re: "guix deploy" is in git master

[Thompson, David]

On Mon, Jul 8, 2019 at 3:29 PM Ricardo Wurmus <address@hidden> wrote:
>
> Similarly, it would be great if “guix deploy” would continue deploying
> other machines in the list even if one of them couldn’t be deployed due
> to an error.  I have a list of 24 machines and a few of them fail with
> the user-homes error above.  Would be nice if all the other deployments
> would still go through, because they are independent.

Agreed. Also this should be done in parallel eventually because
updating 24 machines serially is silly.

> (On the other hand, the current behaviour might be desirable in case
> there’s a problem with “guix deploy” itself.  Rather break just one
> machine instead of wrecking the whole site.  Dunno.)

I think we need to make 'guix deploy' robust enough so that we can trust it. :)

This does bring up the question of what to do upon failure. Other
deployment systems that I've worked with (mainly AWS CodeDeploy)
provide some options. First, the user can specify what it means for a
deploy to succeed. Does it have to successfully deploy to each of them
or should it allow some amount of failure? Then, upon failure, the
user can specify whether or not a rollback should happen.  My personal
preference for default behavior right now is to update everything
possible and print out a report so users can see what failed, but I
think ultimately we'll need to provide more options.

We need to also keep in mind that in-place updates to machines is just
a primitive initial use-case.  Things will get really fun when we get
to blue-green deployments in cloud environments because "rollback"
takes on a whole new meaning. :)

- Dave