Bug Reference

CLOUDSTACK-6122

Introduction

Purpose

LXC support was added to CloudStack in 4.2 release. FS : LXC Support in Cloudstack. The objective of this feature is to enhance LXC support by adding more functionality. This document contains design specification of the enhancements.

References

LXC Support in Cloudstack

CLOUDSTACK-922

Feature Specifications

LXC was implemented as hypervisor in cloudstack. Following operations are currently supported:

• Add an LXC cluster 
• Add an LXC host 
• Register an LXC template 
• Spin up an LXC container

LXC containers are created using libvirt in cloudstack. Libvirt domain xml will be modified to support additional features. KVM system Vms are used for LXC, so most of the networking features are already supported.

Storage

• ROOT Disk: NFS and local storage is supported for ROOT Disk
• DATA disk: Support data disk while creating container. Only Ceph based data disk will be supported
• Support attach/detach disk. attach-disk and detach-disk are supported by libvirt (since 1.0.2) for lxc. Same will be leveraged to support attach/detach data volume.
• Support Ceph storage that will appear as block device on host using RBD

  • Configure and create Ceph RBD on host and make it visible in the container using host passthrough configuration

  • <hostdev mode='capabilities' type='storage'>
       <source>
          <block>/dev/rbd1</block>
        </source>
    </hostdev>

• Migrate volume of a stopped container. Container root volume will be migrated across primary storages by copying compressed tar.gz of the root file system. 

Template

Registering a template and  Launching container from template is already supported. Additional functionality:

• Create template from ROOT volume. Template is a compressed tar.gz of the root file system. Create template from volume will copy the tar.gz of the root file system to secondary storage

Networking

 KVM system Vms are used and both VPC and non-VPC are supported. Networking services Source NAT, DNS, PF, LB, Vpn, Firewall, Security Groups, Network ACL are supported. Additionally nic hot-plug to userVm (container) is also supported. 

Console Access

CLOUDSTACK-4990

Below libvirt doesn't seem to work for LXC. autoport option did not assign a port.

<graphics type="vnc" port="-1" autoport="yes" listen="10.147.28.11" keymap="en-us"/>

Database

No changes

New APIs

None

Limitations

• No Console access
• No Live migration
• No migration across clusters
• No snapshot support
• No upload/download volume support
• No template creation from ROOT volume
• No ISO support for create Vm

Additional steps

• set kvmclock.disable=true in /etc/cloudstack/agent/agent.properties
• Fix cgroup co-mounting error in RHEL7: mount -t cgroup -o remount,cpu cpu "/sys/fs/cgroup/cpu,cpuacct"

Open Issues

Min required libvirt version should be documented

LXC version 1.0

Libvirt Version 1.2.1