RFR: 8372615: Many container tests fail when running rootless on cgroup v1

[David Holmes]

On Fri, 28 Nov 2025 15:03:25 GMT, Casper Norrbin <cnorrbin at openjdk.org> wrote:

> Hi everyone,
> 
> Many container tests verify that various resource limits work as expected. However, when running containers in rootless mode on both Docker and Podman with cgroup v1, resource limits are not supported. This causes tests to fail with error messages like: `Resource limits are not supported and ignored on cgroups V1 rootless systems`.
> 
> To address this, we should skip these tests when running on configurations that don't support resource limits, similar to how we already handle other unsupported configurations (e.g., missing container engine or incompatibility with a specific cgroup version or container runtime).
> 
> To check for this, we now need to use `Metrics.systemMetrics().getProvider()` from `jdk.internal.platform.Metrics` to detect cgroup v1. I've added this functionality to `DockerTestUtils`, which is already used by all container tests. As a result, all container tests now need to include the `java.base/jdk.internal.platform` module, even if they don't directly test resource limits.
> 
> Testing:
> * Oracle tiers 1-5
> * Local testing:
>   - `hotspot/jtreg/containers/` 
>   - `jdk/jdk/internal/platform/docker/`
> on cgroup v1/v2 with Podman and Docker in both rootful and rootless configurations

test/lib/jdk/test/lib/containers/docker/DockerTestUtils.java line 142:

> 140:      *
> 141:      * @return true if resource limits are supported in the current configuration
> 142:      * @throws Exception

I don't like this pattern of making a function seem like it is a query by declaring it returns a boolean when in reality it either returns true of throws. These should just be void functions with names like `check_canUseResourceLimits`, and we can elide the fake `if` conditions with unreachable `return` statements in the callers.

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PR Review Comment: https://git.openjdk.org/jdk/pull/28557#discussion_r2575563949