256 lines
6 KiB
Markdown
256 lines
6 KiB
Markdown
# AlmaLinux
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My proof of concept server running this container stack is built on AlmaLinux
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9.4.
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> [!WARNING]
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> Perform `dnf update` immediately
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## [Repositories](https://wiki.almalinux.org/repos/)
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These may not really be necessary to set up, but you should absolutely review
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them and decide for yourself.
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- [AlmaLinux](https://wiki.almalinux.org/repos/AlmaLinux.html)
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- [CentOS SIGs](https://wiki.almalinux.org/repos/CentOS.html)
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- [Extra](https://wiki.almalinux.org/repos/Extras.html)
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- EPEL and CRB
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- `dnf install epel-release`
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- `dnf config-manager --set-enabled crb`
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- ELRepo
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- `dnf install elrepo-release`
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- [RPM Fusion](https://wiki.almalinux.org/documentation/epel-and-rpmfusion.html)
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## Disks
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### Partitions
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Repeat the following steps for all disks that you want to join together into
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one single logical volume.
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```bash
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# Find /dev/sdX paths for disks
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# WARNING: Make sure you confirm the disk is correct
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lsblk -f
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# Clear the partition table
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dd if=/dev/zero of=/dev/sdX bs=512 count=1 conv=notrunc
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dd if=/dev/zero of=/dev/sdY bs=512 count=1 conv=notrunc
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```
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### LVM
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```bash
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# Create physical volume
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pvcreate /dev/sdX
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# Create volume group for disks
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vgcreate library /dev/sdX
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# Add more disks to volume group
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vgextend library /dev/sdY
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# Create logical volume across all disks in volume group
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lvcreate -l100%FREE -n books library
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# Add filesystem to logical volume
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mke2fs -t ext4 /dev/library/books
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# Check it
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e2fsck -f /dev/library/books
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```
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### /etc/systemd/system/volumes-books.mount
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```ini
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[Mount]
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What=/dev/library/books
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Where=/volumes/books
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Type=ext4
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[Install]
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WantedBy=default.target
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```
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> [!NOTE]
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> We could use a different filesystem that allows mount options to set the
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> permissions
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```bash
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chown -R $ctuser:$ctuser /volumes
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```
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## SSH
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SSH is optional, but highly encouraged. Cockpit gives you a terminal too, but
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that's nowhere near as good as what you can do with a real terminal emulator
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and ssh clients.
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```bash
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dnf install openssh-server
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## Generate strong key on your laptop or workstation/desktop
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ssh-keygen -t ed25519 -a 32 -f ~/.ssh/$localhost-to-$remotehost
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## Copy key to AlmaLinux
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ssh-copy-id -i ~/.ssh/$localhost-to-$remotehost $user@$remotehost
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```
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## Override `sshd` config
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We don't want to allow anyone to login as root remotely ever. You must be a
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`sudoer` with public key auth to elevate to root.
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```bash
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printf '%s\n' 'PermitRootLogin no' > /etc/ssh/sshd_config.d/01-root.conf
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printf '%s\n' \
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'PubkeyAuthentication yes' \
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'PasswordAuthentication no' > /etc/ssh/sshd_config.d/01-pubkey.conf
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```
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## Cockpit -> https://ip-addr:9090
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> [!WARNING]
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> I run behind an existing firewall, not in a VPS or cloud provider.
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> ```bash
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> systemctl disable --now firewalld
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> ```
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> [!NOTE]
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> Should be able to set up good firewall with only 22/80/443 open.
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Enable the socket-activated cockpit service and allow it through the firewall.
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```bash
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systemctl enable --now cockpit.socket
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# FIXME: Unnecessary? Default works?
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firewall-cmd --permanent --zone=public --add-service=cockpit
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firewall-cmd --reload
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```
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## Add SSH keys
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> [!TIP]
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> Skip if you copied your keys with `ssh-copy-id` above.
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`Accounts` -> `Your account` -> `Authorized public SSH keys` -> `Add Key`
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## Install SELinux troubleshoot tool
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This is a component for Cockpit.
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```bash
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dnf install setroubleshoot-server
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```
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## Podman
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Podman is a daemonless container hypervisor. This document prepares a fully
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rootless environment for our containers to run in.
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## Install
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```bash
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dnf install podman
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systemctl enable --now podman
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```
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> [!NOTE]
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> Read the docs.
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> `man podman-systemd.unit`
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## Prepare host networking stack
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### slirp4netns
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> [!NOTE]
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> This may not be necessary but my system is currently using it.
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```bash
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dnf install slirp4netns
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```
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### Install DNS server for `podman`
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> [!NOTE]
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> Not sure how to resolve these correctly yet but the journal logs it
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> so it's running for something.
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```bash
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dnf install aardvark-dns
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```
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### Allow rootless binding port 80+
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> [!NOTE]
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> This is only necessary if you are setting up the reverse proxy.
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```bash
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printf '%s\n' 'net.ipv4.ip_unprivileged_port_start=80' > /etc/sysctl.d/99-unprivileged-port-binding.conf
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sysctl -w net.ipv4.ip_unprivileged_port_start=80
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```
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### Allow containers to route within multiple networks
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```bash
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printf '%s\n' 'net.ipv4.conf.all.rp_filter=2' > /etc/sysctl.d/99-reverse-path-loose.conf
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sysctl -w net.ipv4.conf.all.rp_filter=2
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```
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## Prepare container user
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This user will be the owner of all containers with no login shell or root
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privileges.
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```bash
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# Prepare a group id outside of the normal range
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groupadd --gid 2000 $ctuser
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# Create user with restrictions
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# We need the $HOME to live in
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useradd --create-home \
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--shell /usr/bin/false \
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--password $ctuser_pw \
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--no-user-group \
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--gid $ctuser \
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--groups systemd-journal \
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--uid 2000 \
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$ctuser
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# Lock user from password login
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usermod --lock $ctuser
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# Add container sub-ids
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usermod --add-subuids 200000-299999 --add-subgids 200000-299999 $ctuser
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# Start $ctuser session at boot without login
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loginctl enable-linger $ctuser
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```
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> [!TIP]
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> Optionally setup ssh keys to directly login to $ctuser.
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### Setup $ctuser env
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> [!NOTE]
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> The login shell doesn't exist. Launch `bash -l` manually to get a shell or
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> else your `ssh` will exit with a status of 1.
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```bash
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# Switch to user (`-i` doesn't work without a login shell)
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machinectl shell $ctuser@ /bin/bash
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# Create dirs
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mkdir -p ~/.config/{containers/systemd,environment.d}
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# Prepare `systemd --user` env
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echo 'XDG_RUNTIME_DIR=/run/user/2000' >> ~/.config/environment.d/10-xdg.conf
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# Enable container auto-update
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podman system migrate
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# WARNING: Set strict versions for all containers or risk catastrophe
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systemctl --user enable --now podman-auto-update
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exit
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```
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> [!WARNING]
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> I disabled SELinux to not deal with this for every container.
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> /etc/selinux/config -> `SELINUX=disabled`
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> [!TIP]
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> Set up the correct policies permanently instead of disabling SELinux
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Temporarily set SELinux policy to allow containers to use devices.
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```bash
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setsebool -P container_use_devices 1
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```
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