De-deprecate "runtime"

[AkihiroSuda]

What is the problem you're trying to solve
Allow using third party runtimes such as Kata Containers and gVisor

Describe the solution you'd like
Remove "DEPRECATED: this attribute is low-level platform implementation detail" from runtime: https://github.com/compose-spec/compose-spec/blob/master/spec.md#runtime

Additional context
runtime was ported from compose v2 and marked as "DEPRECATED" in ce585a8#diff-958e7270f96f5407d7d980f500805b1bR1193 (#78 )

Previous discussion: docker/compose#6239 (closed by the stale bot)

[AkihiroSuda]

PR: #102

[EricHripko]

From what I understand, the reasoning behind marking this as deprecated was because its a non-portable/low-level setting that is arguably better placed elsewhere rather than compose.yml. Given that this is attribute is still supported, what's the goal of de-deprecating this?

[AkihiroSuda]

elsewhere

where?

Given that this is attribute is still supported, what's the goal of de-deprecating this?

The goal is to ensure it to be supported permanently

[EricHripko]

In the Compose implementation itself. Please also note that Compose implementations are not required to implement all the attributes. I think we can summon @ndeloof for additional context around this attribute.

[ndeloof]

to ensure it to be supported permanently
supporting this attribute will be a decision by Compose implementations

The reason for deprecation is indeed that this exposes a low-level implementation detail that hardly make sense in a compose high-level application description.

The runtime attribute only exists to support legacy approach to enable Nvidia GPUs, which required to replace runc with a custom runtime. This is obsolete today with container hooks support in engine and --gpu option (see https://docs.docker.com/config/containers/resource_constraints/#gpu). Within compose file format, we are discussing a proposal to add GPU support here

[AkihiroSuda]

This proposal is for supporting Kata and gVisor, not for supporting GPUs

[ndeloof]

ok then
👍

[EricHripko]

Is this something that makes sense as a machine-wide setting? Cannot think off top of my head of an example where one would want to mix-and-match containers running using different runtimes (would this work at all?)

[AkihiroSuda]

gVisor has non-trivial issues on performance and compatibility, so runtime: gvisor is mostly expected to set only for non-DB containers.

[EricHripko]

Thanks for sharing this insight 👍