proxmox lxc

linux/Proxmox LXC.md

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+# Proxmox LXC
+
+## About
+- LXC is system container (like docker container, but instead of just one app, LXC is for complete system/OS)
+- in term of performance and isolation, LXC is middle ground between full virtualization (e.g.: QEMU/KVM) and containerization (e.g.: docker)
+
+## Converting Proxmox Container to LXC
+- must check OS compatibility (check file: `/usr/share/perl5/PVE/LXC/Setup/(distro).pm` )
+- unprivileged container is preferred if possible (e.g.: need mknod, permission problem)
+- some feature flags may be needed (e.g.: FUSE, nesting)
+- reference: https://github.com/my5t3ry/machine-to-proxmox-lxc-ct-converter/blob/master/convert.sh
+- ssh host roles:
+    - proxmox hypervisor (called "proxmox")
+    - guest OS that will be converted (called "guest")
+    - copier that can connect via ssh to guest OS and copy its whole filesystem, proxmox host can also play this role (called "copier")
+- run this command on proxmox host:
+```bash
+collectFS() {
+    tar -czvvf - -C / \
+      --exclude="sys" \
+      --exclude="dev" \
+      --exclude="run" \
+      --exclude="proc" \
+      --exclude="*.log" \
+      --exclude="*.log*" \
+      --exclude="*.gz" \
+      --exclude="swap.img" \
+      --exclude="swapfile" \
+  .
+}
+```
+- make sure copier can ssh to guest OS as root
+- then copy the filesystem image from proxmox host (via copier if needed):
+```bash
+# without copier
+ssh root@guest "$(typeset -f collectFS); collectFS" > /var/lib/vz/template/cache/my_custom_filesystem.tar.gz
+
+# via copier
+ssh -J kristian@copier root@guest "$(typeset -f collectFS); collectFS" > /var/lib/vz/template/cache/my_custom_filesystem.tar.gz
+```
+- use the newly copied filesystem as LXC template (can create from web GUI)
+
+#### Diagnose Failed to Start
+- start LXC manually via:
+```bash
+lxc-start -n 102 -F -l DEBUG -o /tmp/my_lxc.log
+```
+
+#### Example Problem: Missing Basic FHS Directory
+- sometime, because we add to ignore /sys /dev/ /run /proc, the template filesystem did not contain those directory, not even empty ones
+- to check if basic FHS directory exists, mount the filesystem first:
+```bash
+pct mount 102
+mount # shows that mount point is in /var/lib/lxc/102/rootfs
+cd /var/lib/lxc/102/rootfs
+mkdir sys
+mkdir dev
+mkdir run
+mkdir proc
+cd ~
+pct nmount 102
+```
+
+#### Configurations:
+- network (static/dynamic IPv4/IPv6, default gateway/route, nameserver/dns, vlan tagging)
+- consider if guest OS ssh keys need to be regenerated or use older ones (can backup then restore `/etc/ssh` directory content)
+
+#### Known Problem:
+- when assigning 2 interface with different IP address, both MAC address replied to ARP request (might cause problem with some network appliance)
+- incompatibility with guest OS ubuntu older than 12.04 or debian older than 4, cannot use unmanaged (not debugged yet)
+- ...