cmd_erase requires root privileges and does not take rpm_root, root and urpm_root arguments

[papoteur-mga]

When trying to test with the function cmd_erase, hoping to erase package previously installed in a chroot, the command is stopped by not having root privileges.
When removing this stop, it fails too because it tries to use /var/lib:
PermissionError: [Errno 13] Permission denied: '/var/lib/rpm/.urpm-install.lock'

[pvi-github]

Hi papoteur-mga,

I think this is an argparse Namespace issue in your test rather than a bug in cmd_erase itself.

cmd_erase already supports the "user-owned chroot" pattern you're trying to use — in exactly the same way cmd_install is used in the existing tests. You just need to pass the right attributes in your Namespace:

args = argparse.Namespace(
    packages=["some-package"],
    root="/path/to/your/chroot",   # or urpm_root=...
    allow_no_root=True,            # ← the key: bypasses the root check
    auto=True,
    auto_orphans=False,
    keep_orphans=False,
    force=False,
    test=False,
    sync=True,
    erase_recommends=False,
    keep_suggests=False,
    debug=None,
)
cmd_erase(args, chroot_db)

The three pieces that make non-root chroot operation work are already in place in urpm/cli/commands/remove.py:

• Root check bypass via allow_no_root — lines 49-52 (remove.py#L49-L52)
• Lock inside the chroot — InstallLock(root=install_root) at lines 226-227 uses the chroot path for the lock file (<root>/var/lib/rpm/.urpm-install.lock) instead of the host path
• User namespaces — use_userns=bool(allow_no_root and rpm_root) at line 243 runs rpm through unshare when we're not root

The PermissionError: /var/lib/rpm/.urpm-install.lock you're seeing comes from the fact that your Namespace probably has neither root nor urpm_root set — so install_root falls back to None and the lock ends up on the host path, where you don't have write access.

You can look at the helper in urpm/tests/test_install.py:180-211 which builds its Namespace exactly this way for cmd_install (note line 203: allow_no_root=True).

That said, the fact that you had to dig for this points to two gaps we should close (added to TODO.md):

1. Expose --allow-no-root as a CLI flag for install/upgrade/erase, so end users can drive a user-owned chroot from the command line without going through the internal Python API.
2. Modify an existing image (urpm install/upgrade/erase --root /image) — a natural use case for iterating on a dev image without rebuilding it from scratch.

Both will land in a future release. For your immediate test, allow_no_root=True + root=<chroot> in the Namespace should be enough.