Run bootc install failed with `STORAGE_OPTS=additionalimagestore=/run/host-container-storage` on FCOS

[HuijingHei]

Use bcvk to start quay.io/fedora/fedora-coreos:testing-devel libvirt VM with --bind-storage-ro, then run bootc install failed.

• Start VM with --bind-storage-ro

sudo bcvk libvirt run --name test --filesystem xfs --disk-size 20G --bind-storage-ro --firmware uefi-secure quay.io/fedora/fedora-coreos:testing-devel
sudo bcvk libvirt ssh test

• Run bootc install with env STORAGE_OPTS=additionalimagestore=/run/host-container-storage

podman run --rm --privileged -v /dev:/dev -v /var/lib/containers:/var/lib/containers -v /:/target \
--pid=host --security-opt label=type:unconfined_t \
localhost/bootc-integration:latest \
env BOOTC_BOOTLOADER_DEBUG=1 RUST_LOG=trace STORAGE_OPTS=additionalimagestore=/run/host-container-storage bootc install to-existing-root --skip-fetch-check --acknowledge-destructive --root-ssh-authorized-keys /target/root/.ssh/bcvk-id_rsa.pub --karg=console=ttyS0,115200n8

....
DEBUG open_image: opening image self=ImageProxy imgref="containers-storage:quay.io/curl/curl-base:latest"
TRACE open_image:impl_request_with_fds: sending request OpenImage self=ImageProxy imgref="containers-storage:quay.io/curl/curl-base:latest" self=ImageProxy method="OpenImage"
error: Installing to filesystem: resolving bound image quay.io/curl/curl-base:latest: failed to invoke method OpenImage: overlay: can't stat imageStore dir /run/host-container-storage: stat /run/host-container-storage: no such file or directory

Additionally, from the error logs can not find /run/host-container-storage, the workaround is when running podman, add -v /run/host-container-storage:/run/host-container-storage.

[HuijingHei]

On github runner, running podman with -v /run/host-container-storage:/run/host-container-storage:ro , and with STORAGE_OPTS=additionalimagestore=/run/host-container-storage when running bootc, get error: readdir: Too many open files.

podman run \
        --rm --privileged \
        -v /dev:/dev \
        -v /run/host-container-storage:/run/host-container-storage:ro \
        -v /:/target --pid=host \
        --security-opt label=type:unconfined_t \
        localhost/bootc-integration:latest \
        env BOOTC_BOOTLOADER_DEBUG=1 STORAGE_OPTS=additionalimagestore=/run/host-container-storage \
                bootc install to-existing-root \
                --stateroot=default \
                --skip-fetch-check \
                --acknowledge-destructive \
                --karg=console=ttyS0,115200n8
        content: error: Installing to filesystem: Gathering source info from container env: Subprocess failed:         ExitStatus(unix_wait_status(256))
        content: error: readdir: Too many open files