uCore Documentation

To use uCore as an NFS server, you must configure the firewall, SELinux contexts, and the service itself.

1. Firewall Configuration

Add the NFS service to the FedoraServer zone:

sudo firewall-cmd --permanent --zone=FedoraServer --add-service=nfs
sudo firewall-cmd --reload

2. SELinux Configuration

By default, nfs-server is blocked from sharing directories. You must set the appropriate context.

For Read-Only shares:

sudo semanage fcontext --add --type "public_content_t" "/path/to/share/ro(/.*)?"
sudo restorecon -R /path/to/share/ro

For Read-Write shares:

sudo semanage fcontext --add --type "public_content_rw_t" "/path/to/share/rw(/.*)?"
sudo restorecon -R /path/to/share/rw

Simplest (Least Secure) Method: To allow sharing anything without specific context management:

• Read-only: sudo setsebool -P nfs_export_all_ro 1
• Read-write: sudo setsebool -P nfs_export_all_rw 1

3. Service Management

Enable and start the service:

sudo systemctl enable --now nfs-server.service

4. Export Configuration

Configure shares in /etc/exports or /etc/exports.d/*.

# Example: Enable RW NFS sharing via SELinux booleans
sudo setsebool -P nfs_export_all_rw 1

# Example: Start the service
sudo systemctl enable --now nfs-server.service

The fastest way to install uCore is to use a Butane template to generate an Ignition file that automatically rebases the system to a uCore image during the initial Fedora CoreOS installation.

Prerequisites:

• You must follow the Fedora CoreOS bare metal installation guide.
• You must produce an Ignition file that, at minimum, sets a password and an SSH key for the default user (core).

Steps:

1. Use examples/ucore-autorebase.butane as a template. Replace YOUR_GOOD_PASSWORD_HASH_HERE with your actual password hash and add your SSH public key.
2. Generate an Ignition file from your Butane configuration using the butane utility.
3. Install CoreOS on your target platform (hypervisor, cloud, or bare-metal) using the coreos-installer and point it to your Ignition file via --ignition-url or --ignition-file.

Tip: Test your Ignition configuration in a VM before attempting a bare-metal installation.

sudo coreos-installer install /dev/nvme0n1 --ignition-url https://example.com/ucore-autorebase.ign

To use uCore as a Samba server, configure the firewall, SELinux, and the service.

1. Firewall Configuration

sudo firewall-cmd --permanent --zone=FedoraServer --add-service=samba
sudo firewall-cmd --reload

2. SELinux Configuration

Set the samba_share_t context on your directories:

sudo semanage fcontext --add --type "samba_share_t" "/path/to/share(/.*)?"
sudo restorecon -R /path/to/share

Simplest (Least Secure) Method: To allow Samba to share anything: sudo setsebool -P samba_export_all_rw 1

3. Service Management

sudo systemctl enable --now smb.service

4. Share Configuration

Manual configuration is done in /etc/samba/smb.conf. Alternatively, use user shares via: net usershare add sharename /path/to/share [comment] [user:{R|D|F}] [guest_ok={y|n}]

# Example: Enable Samba service
sudo systemctl enable --now smb.service

# Example: Set SELinux context for a specific share
sudo semanage fcontext --add --type "samba_share_t" "/var/home/myshare(/.*)?"
sudo restorecon -R /var/home/myshare

ZFS kernel modules and tools are pre-installed but not loaded by default.

1. Loading the Module

Load it manually with modprobe zfs. To ensure it loads automatically at boot, create a configuration file:

echo zfs > /etc/modules-load.d/zfs.conf

2. Creating Zpools on an Immutable Root

Because the uCore root filesystem (/) is immutable, you cannot create directories for mountpoints directly in /. Always specify a mountpoint in a writable location (like /var) when creating a pool:

Correct:

zpool create -m /var/tank tank /dev/sdb

To fix an existing pool with the wrong mountpoint:

zfs set mountpoint=/var/tank tank

3. ZFS Scrub Timers

You can enable built-in timers to periodically run zpool scrub for data integrity:

• Weekly: systemctl enable --now zfs-scrub-weekly@<pool>.timer
• Monthly: systemctl enable --now zfs-scrub-monthly@<pool>.timer

4. Backups with Sanoid/Syncoid

ucore includes sanoid and syncoid.

• Sanoid: Use it for automated snapshots. Create a sanoid.conf in /etc/sanoid (use a template from the sanoid repo) and enable the timer: systemctl enable sanoid.timer.
• Syncoid: Use it for ZFS replication. For a "pull" configuration, create a syncoid.service and syncoid.timer in /etc/systemd/system/ and enable the timer.

# Load ZFS at boot
echo zfs > /etc/modules-load.d/zfs.conf

# Create a pool with a writable mountpoint
zpool create -m /var/tank tank /dev/sdb

# Enable weekly scrub
systemctl enable --now zfs-scrub-weekly@tank.timer