Re: [BuildStream] BuildGrid and BuildStream 1.4 and API concerns

[Tristan Van Berkom <tristan vanberkom codethink co uk>]

On Sun, 2018-12-02 at 11:48 +0100, Jürg Billeter wrote:
> Hi Tristan,
>
> On Sun, 2018-12-02 at 19:34 +0900, Tristan Van Berkom via BuildStream-
> list wrote:
> > To clarify, I am also very much against the bundling approach, as it
> > implies a lot of logistic overhead, just for a situation which will
> > hopefully only last one release cycle.
>
> Besides the mentioned pain with bundling, I also don't think it would
> be useful at all. For normal remote execution, you want to install
> BuildGrid on a different system than BuildStream and there will
> typically be multiple clients. So I don't see in what way bundling
> would help with potential incompatibilities.
>
> If BuildGrid breaks compatibility with a particular BuildStream release
> at some point, we need to clearly document which version of BuildGrid
> can be used with which version of BuildStream in the installation
> instructions. However, I don't see a point of actual bundling. Or am I
> misunderstanding something here?

I was thinking we would probably install it under a different binary
name (e.g. bst-buildgrid), and only consume upstream versions which
don't break compatibilty for the duration of a given cycle.

At least this makes the user story closer to what we currently have
with the artifact server; that users might have to upgrade and
reinstall it for a minor point release of BuildStream.

But indeed, as you mention the installations happen on different
machines, and even then, BuildStream has a decent compatibility story
since CAS that would not be as good.

Even if there is not backwards compat from BuildGrid, at least
advertising the version so as to allow clients to bail out gracefully
when an incompatibility is discovered I think is a must, and comes at
little or no cost to BuildGrid, am I missing something that makes this
difficult ?

Surely, we are already dependent on features which are not part of the
spec, depending on versioning should not be a problem right ?

Cheers,
    -Tristan