ComposeService::user/group (compose_file.{h,cpp}) parse a "user[:group]"
key, split on the first ':' the same way an image's own declared USER is
split (oci_image.cpp). start_compose_services() passes both straight
through to run_mounted_container()'s existing user/group parameters, which
already fall back to the image's own declared user when unset -- the same
default -r/--run itself has when --user isn't given.
Verified end to end on the real target machine (root, via the scoped doas
rule), checked via `ps -eo pid,ppid,uid,cmd` (not -x/--exec, see below):
the actual sandboxed command runs as the resolved uid/gid, matching plain
-r --user's own already-working behavior.
Also recorded in TODO.md: verifying this surfaced a real but unrelated
bug in resolve_namespace_pid() (sandbox_process.cpp), which -x/--exec's
own default-identity resolution uses -- it stops at bwrap's own pid-1
namespace supervisor instead of walking one level deeper to the real
(correctly priv-dropped) target, so `-x/--exec <pid> -- id` with no
explicit --user misreports root for a session that's actually running as
a non-root user the whole time. Not a regression from this change and not
fixed here.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Gv3s5jckJKzh6JkMoi2Akz
ceamac
6624fd3ab5