rb-sys-dock's base image is past EOL

[sxlijin]

rb-sys-dock depends on CentOS 7, which as of Jul 1 is EOL.

For me, this manifested as an inability to build OpenSSL dependencies: I need to yum install perl-IPC-Cmd to make x86_64-linux builds work, and that fails with this error:

Loaded plugins: fastestmirror, ovl
Determining fastest mirrors
Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=container error was
14: curl#6 - "Could not resolve host: mirrorlist.centos.org; Unknown error"

gh workflow logs: https://github.com/BoundaryML/baml/actions/runs/10066707009/job/27828665640

centos mirrorlist deprecation: https://serverfault.com/questions/1161816/mirrorlist-centos-org-no-longer-resolve

[sxlijin]

Posted on rake-compiler/rake-compiler-dock#122 (comment)