Using pct in Proxmox VE

Proxmox VE (PVE) is a powerful open-source virtualization platform that supports both LXC containers and KVM virtual machines. The pct command line tool is specifically designed to manage LXC containers. Below is a detailed step-by-step guide to help master the pct command.

1. Prerequisites

Before using pct, ensure:

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  • Necessary OS templates (e.g., Ubuntu, Debian, CentOS) are downloaded from the Proxmox template repository.

2. Basic Commands

2.1 Create a New Container

To create a new LXC container, use the pct create command.

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pct create <vmid> <ostemplate> [options]

Example:

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pct create 100 local:vztmpl/ubuntu-22.04-standard_22.04-1_amd64.tar.gz \
  --storage local-lvm \
  --rootfs 8G \
  --hostname LXC-100 \
  --memory 1024 \
  --cores 1 \
  --net0 name=eth0,bridge=vmbr0,ip=dhcp

Explanation:

  • 100: The unique ID for the container.
  • local:vztmpl/ubuntu-22.04-standard_22.04-1_amd64.tar.gz: The OS template to use.
  • --storage local-lvm: The storage where the container will be created.
  • --rootfs 8G: Allocate 8GB of disk space for the root filesystem.
  • --hostname LXC-100: Set the hostname for the container.
  • --memory 1024: Allocate 1024MB of RAM.
  • --cores 1: Assign 1 CPU core.
  • --net0: Configure the network interface (DHCP in this case).

2.2 Start a Container

To start a container, use the pct start command.

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pct start <vmid>

Example:

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pct start 100

2.3 Stop a Container

To stop a running container, use the pct stop command.

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pct stop <vmid>

Example:

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pct stop 100

2.4 Restart a Container

To restart a container, use the pct restart command.

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pct restart <vmid>

Example:

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pct restart 100

2.5 Access the Container’s Shell

To access the container’s shell, use the pct enter command.

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pct enter <vmid>

Example:

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pct enter 100

2.6 List All Containers

To list all containers on the node, use the pct list command.

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pct list

Output Example:

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VMID       Status     Lock         Name
100        running                 lxc-100
101        stopped                 lxc-101

2.7 Modify Container Configuration

To modify a container’s configuration, use the pct set command.

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pct set <vmid> [options]

Example (Increase Memory Limit):

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pct set 100 --memory 2048

Example (Add a Mount Point):

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pct set 100 --mp0 /mnt/data,/mnt/data,ro

2.8 Clone a Container

To clone an existing container, use the pct clone command.

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pct clone <source-vmid> <new-vmid> [options]

Example:

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pct clone 100 101 --storage local-lvm

2.9 Backup a Container

To create a backup of a container, use the vzdump command.

Example:

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Backup Container ID 302 (Stopped Mode)

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vzdump 302 --compress zstd --mode stop --storage local

Backup Container ID 101 (Snapshot Mode)

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vzdump 101 --compress lzo --mode snapshot --storage nas_backup

--compress: gzip (standard), lzo (fast), zstd (best balance)

--mode:

  • stop (service interruption, maximum consistency)
  • snapshot (live backup, requires supported filesystem)

--storage: Target storage ID (view with pvesm list)

Multi LXC Backup

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vzdump 100 101 102 --mode stop --storage local --compress zstd

2.10 Restore a Container

To restore a container from a backup, use the pct restore command.

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pct restore <vmid> <backup-file> [options]

Example:

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pct restore 100 /var/lib/vz/dump/vzdump-lxc-100-2023_10_01-12_00_01.tar.gz

2.11 Destroy a Container

To permanently delete a container.

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pct destroy <vmid> --purge
  • <vmid>: The ID of the container to be destroyed.
  • --purge: Removes all associated data, including backups and configuration files.

Example:

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pct destroy 100 --purge

3. Advanced Usage

3.1 Mount Host Directories

Directories from the host can be mounted into the container.

Example:

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pct set 100 --mp0 /mnt/host-data,/mnt/container-data,ro

3.2 Configure Networking

Static IPs or additional network interfaces can be configured.

Example (Static IP):

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pct set 100 --net0 name=eth0,bridge=vmbr0,ip=192.168.1.100/24,gw=192.168.1.1

Set VLAN

Static IP Example:

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pct set 100 --net0 name=eth0,bridge=vmbr0,tag=10,ip=192.168.10.100/24,gw=192.168.10.1
  • Sets the VLAN tag to 10 for the eth0 interface.
  • Connects the interface to the vmbr0 bridge.
  • Assigns a static IP address 192.168.10.100/24 and gateway 192.168.10.1.

DHCP Example:

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pct set 100 --net0 name=eth0,bridge=vmbr0,tag=10,ip=dhcp
  • Multiple network interfaces can be configured by incrementing the --netX option (e.g., --net1, --net2).
  • Ensure the VLAN is properly configured on the Proxmox host’s network bridge (e.g., vmbr0 or vmbr1).

3.3 Resource Limits

CPU and memory limits can be set for the container.

Example:

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pct set 100 --memory 4096 --cores 2

4. Troubleshooting

  • Container Fails to Start: Check logs using pct logs <vmid>.
  • Network Issues: Verify the network configuration with pct config <vmid>.

5. Help and Documentation

  • Use pct help to see a list of available commands.
  • For detailed documentation, use man pct.

6. Automate to creation of an LXC container in Proxmox VE (PVE).

Script Overview

  1. Prompts the user for input (LXC ID and password).
  2. Checks if the LXC ID already exists and handles conflicts.
  3. Downloads the LXC template if it doesn’t already exist.
  4. Creates a new LXC container with specified configurations.
  5. Appends additional configuration to the container’s configuration file.
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bash -c "$(wget -qLO - https://kingtam.eu.org/scripts/lxc-create.sh)"

7. Initialization of the environment when deploying a custom LXC.

Script Overview

  1. Install packages: git, wget, curl, tree, iperf3, vim, tmux
  2. Add a user
  3. Enable tab completion
  4. Retrieve public key from GitHub
  5. Install VIM-PLUG
  6. Configure tmux
  7. Exit
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bash -c "$(wget -qLO - https://kingtam.eu.org/scripts/linux-init.sh)"

Conclusion

The pct command line tool is a powerful way to manage LXC containers in Proxmox VE. With this guide, creating, configuring, and managing containers efficiently should be straightforward. For further questions or assistance, additional resources are available in the Proxmox documentation.