buildah-unshare - Run a command inside of a modified user namespace.
buildah unshare [
options] [
--] [
command]
Launches a process (by default,
$SHELL) in a new user namespace. The user
namespace is configured so that the invoking user's UID and primary GID appear
to be UID 0 and GID 0, respectively. Any ranges which match that user and
group in /etc/subuid and /etc/subgid are also mapped in as themselves with the
help of the
newuidmap(1) and
newgidmap(1) helpers.
buildah unshare is useful for troubleshooting unprivileged operations and for
manually clearing storage and other data related to images and containers.
It is also useful if you want to use the
buildah mount command. If an
unprivileged user wants to mount and work with a container, then they need to
execute buildah unshare. Executing
buildah mount fails for unprivileged
users unless the user is running inside a
buildah unshare session.
--mount,
-m [
VARIABLE=]containerNameOrID
Mount the
containerNameOrID container while running
command, and
set the environment variable
VARIABLE to the path of the mountpoint. If
VARIABLE is not specified, it defaults to
containerNameOrID,
which may not be a valid name for an environment variable.
buildah unshare id
buildah unshare pwd
buildah unshare cat /proc/self/uid_map /proc/self/gid_map
buildah unshare rm -fr $HOME/.local/share/containers/storage /run/user/`id
-u`/run
buildah unshare --mount containerID sh -c 'cat ${containerID}/etc/os-release'
If you want to use buildah with a mount command then you can create a script
that looks something like:
cat buildah-script.sh << _EOF
#!/bin/sh
ctr=$(buildah from scratch)
mnt=$(buildah mount $ctr)
dnf -y install --installroot=$mnt PACKAGES
dnf -y clean all --installroot=$mnt
buildah config --entrypoint="/bin/PACKAGE" --env "FOO=BAR" $ctr
buildah commit $ctr imagename
buildah unmount $ctr
_EOF
Then execute it with:
buildah unshare buildah-script.sh
buildah(1),
buildah-mount(1),
namespaces(7),
newuidmap(1),
newgidmap(1),
user_namespaces(7)