[OE-core] [OE-Core][PATCH] openssh: Add dependency on ssh for sftp

[Alex Kiernan]

On Thu, Jul 5, 2018 at 9:58 AM Mike Looijmans <mike.looijmans at topic.nl> wrote:
>
> On 02-07-18 23:13, Richard Purdie wrote:
> > On Mon, 2018-07-02 at 18:44 +0100, Alex Kiernan wrote:
> >> On Mon, Jul 2, 2018 at 4:06 PM Alex Kiernan <alex.kiernan at gmail.com>
> >> wrote:
> >>>
> >>> On Mon, Jul 2, 2018 at 3:55 PM Mike Looijmans <mike.looijmans at topic
> >>> .nl> wrote:
> >>>>
> >>>> The sftp-server runs fine using dropbear as SSH backend, I'd
> >>>> expect the same
> >>>> to be true for the client. Isn't that the case, and will the sftp
> >>>> client only
> >>>> work with openssh's ssh?
> >>>>
> >>>
> >>> Interesting question... I hadn't realised dropbear didn't have an
> >>> sftp
> >>> client, but it's clearly a supported combination:
> >>>
> >>> https://github.com/mkj/dropbear/blob/1656db9e58e7e8188e4ca27ae4892b
> >>> 14949c56a5/dbclient.1#L159
> >>>
> >>> I'll amend the patch so it depends on ssh not ${PN}-ssh since both
> >>> dropbear and openssh provide that.
> >>>
> >>
> >> Hmm... only that gets you this warning:
> >>
> >> NOTE: Multiple providers are available for runtime ssh (dropbear,
> >> openssh)
> >> Consider defining a PREFERRED_RPROVIDER entry to match ssh
> >>
> >> If you've not set it, which feels like a pretty poor upgrade
> >> experience; I'm not sure how best to deal with that.
> >
> > This is not an easy problem to solve. This is why we have the horrible
> > VIRTUAL-RUNTIME_* variables, I wish there were a better way...
> >
> > Basically, bitbake has to have some idea which one to build, letting
> > the package manager decide at do_rootfs time isn't really good enough
> > for deterministic builds.
>
> The dropbear/ssh choice seems to be one that is being postponed until image
> creation time. There's an IMAGE_FEATURE that appears to make the choice:
> IMAGE_FEATURES += "ssh-server-dropbear"
>
> Since you're building openssh already, there's no need to instruct bitbake to
> build more at package compile time.
>
> Using RDEPENDS and PREFERRED_RPROVIDER or VIRTUAL-RUNTIME will 'break' a lot
> of existing setups by installing the wrong ssh client without the engineer
> knowing about it. And it will also make it impossible to build two images with
> different choices. I can imaging you'd want to have a small size "recover"
> image with dropbear and a large size "full" image with openssh in the same
> build for the same machine and distro.
>

So, is the short answer, that there's no good answer and the status
quo is the way to leave it?

--
Alex Kiernan