RFR: 8313718: make container at requires command configurable [v2]

[Mikhailo Seledtsov]

On Wed, 30 Aug 2023 03:25:54 GMT, Mikhailo Seledtsov <mseledtsov at openjdk.org> wrote:

>> Container ecosystem is growing. It would be beneficial to define custom command to figure out whether a specific test host or environment allows for container testing. This enhancement seeks to make the command used by jtreg "requires" extension configurable, specifically test/jtreg-ext/requires/VMProps.java checkContainerSupport().
>
> Mikhailo Seledtsov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fixed initialization issue

David,
  We already have a way to configure engine executable, that is 'docker' vs 'podman' vs 'some-other-engine'. However the command that we use to test whether the engine is available and working on a given test host is "<CONTAINER_ENGINE> ps". However the "ps" sub-command may not be applicable for all container types, and it may be "heavy" at times on some busy hosts.
  One option is to replace it with something more universal and light-weight, such as "<CONTAINER_ENGINE> help". The "help" command should be available for all containers, and be reasonably light-weight. 
  The other option is to make it fully configurable as this change. 
It would also be good to have an ability to skip such check entirely for hosts know to be properly configured.

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PR Comment: https://git.openjdk.org/jdk/pull/15475#issuecomment-1701413581