[webkit-dev] Proposal to update WebKitGTK dependency policy

[Michael Catanzaro]

On Thu, Feb 17 2022 at 05:41:34 PM +0000, Carlos Alberto Lopez Perez 
via webkit-dev <webkit-dev at lists.webkit.org> wrote:
> If I understand this correctly, that would mean that we would have to
> support the libraries that we rely on, up to a version that may be 
> quite
> old.
> 
> Right now we are supporting a cycle of 2+1=3 (both debian and ubuntu
> release each 2 years). And this change would mean that we would have 
> to
> extend the period up to 3+2=5 which is quite more.

Yes.

> I think this may cause tension in the future regarding supporting the
> usual GNOME libraries that move fast: GTK, GStreamer, etc

Possibly, yes. In practice, I think we're already in the habit of 
keeping #ifs for older dependencies around for longer than is required 
by our policy, so I suspect it will probably not be *too* annoying 
compared to our current practice.

I wish this would benefit Ubuntu as well, but in practice it won't, 
since they cannot keep up with our toolchain requirements, and Apple 
doesn't want to support older toolchains. That's tough to square. :/

> To give some data, the last version of RHEL is 9 (released on Nov 
> 2021)

Nov 2021 was RHEL 9 beta. We are planning to release RHEL 9.0 this 
coming spring.

> which means that we would support RHEL 8 up to Nov 2023. And RHEL 8 
> was
> released on May 2019 and includes this versions of libraries we use:
> 
> gstreamer = 1.16
> gtk = 3.22
> glib = 2.56
> libsoup = 2.62
> cairo = 1.15
> icu = 60.3

Yes, though keep in mind I'm proposing to match the latest minor 
release (currently RHEL 8.5), not the earliest minor release (RHEL 
8.0). We used to update desktop package versions fairly aggressively in 
RHEL 7 (so long as they don't break API/ABI), but in RHEL 8 we have 
been more conservative and have mostly stopped doing so. So in 
practice, yes, most of those versions are indeed unlikely to change.

> Also if we are going to do this, and we are serious about it, then we
> would need at least two new buildbots at build.webkit.org for testing
> the build on the last two versions of RHEL.
> Is RedHat going to provide the resources for the bots and is going to
> help taking care of things when they broke there?

That seems like a reasonable request. I'll delay modifying the policy 
until I'm able to provide an answer regarding the requested bots. We'd 
probably have them run CentOS Stream rather than actual RHEL. I suppose 
that's what we should target with the dependencies policy, as well, 
since it's simpler than having to know the difference between different 
RHEL minor releases.

What we *really* want most of all is JSC EWS for aarch64, ppc64le, and 
s390x. Adding a couple x86_64 buildbots should be comparatively easy....

Michael