Linux Containers

Many of CSCF's servers run using LXC (LinuX Containers) (see: http://en.wikipedia.org/wiki/LXC )

Here we document the most useful commands for working with these containers

Background information

• Ubuntu documentation: https://help.ubuntu.com/12.04/serverguide/lxc.html
  • https://help.ubuntu.com/16.04/serverguide/lxc.html

• man pages for lxc and friends

• http://lxc.sourceforge.net/ top-level now redirects to
  • https://linuxcontainers.org/
    Perhaps there see...
    • https://linuxcontainers.org/lxc/
      • https://linuxcontainers.org/lxc/news/

• CSCF non-twiki LXC documentation (Dave)

    LXD — Just Say No!

• You may stumble across the presumptuously-named lxd package. For now we avoid that for a number of reasons.
  • https://linuxcontainers.org/lxd/
  • https://help.ubuntu.com/16.04/serverguide/lxd.html

Names of current container host servers

• https://cs.uwaterloo.ca/cscf/student/hosts currently contains a list of many container hosts. To access the hostname use the domain ".cloud.cs.uwaterloo.ca" or ".storage.cs.uwaterloo.ca". (I'm currently not sure what difference there is to using either). You might also be able to search Infoblox and find host names that way.
• https://cs.uwaterloo.ca/cscf/cscfnow/inventory/lxc-Container-list.shtml has an automatically generated list of the state of containers on each IAAS host.

Listing the containers on a server

• lxc-ls

root@mc-cloud002-n1:# lxc-ls
bs002.student.cs.uwaterloo.ca  db2a.student.cs.uwaterloo.ca  mails.student.cs.uwaterloo.ca     postgres060.student.cs.uwaterloo.ca
bs004.student.cs.uwaterloo.ca  flexlm202.cscf.uwaterloo.ca   mysql070.student.cs.uwaterloo.ca  region.student.cs.uwaterloo.ca
bs004.student.cs.uwaterloo.ca  flexlm202.cscf.uwaterloo.ca    mysql070.student.cs.uwaterloo.ca                                            postgres060.student.cs.uwaterloo.ca
db2a.student.cs.uwaterloo.ca   mails.student.cs.uwaterloo.ca  postgres060.student.cs.uwaterloo.ca  region.student.cs.uwaterloo.ca

• lxc-ls -l

root@mc-cloud002-n1:# lxc-ls -l
total 0
drwxr-xr-x 1 root root 56 Nov 13 16:52 bs002.student.cs.uwaterloo.ca
drwxr-xr-x 1 root root 56 Nov 15 12:47 bs004.student.cs.uwaterloo.ca
drwxr-xr-x 1 root root 56 Feb 11 17:26 db2a.student.cs.uwaterloo.ca
drwxr-xr-x 1 root root 56 Sep  5 21:57 flexlm202.cscf.uwaterloo.ca
drwxr-xr-x 1 root root 62 Oct  3 17:37 mails.student.cs.uwaterloo.ca
drwxr-xr-x 1 root root 56 Nov 29 15:23 mysql070.student.cs.uwaterloo.ca
drwxr-xr-x 1 root root 56 Aug 17 19:24 postgres060.student.cs.uwaterloo.ca
drwxr-xr-x 1 root root 56 Jul 19  2012 region.student.cs.uwaterloo.ca
drwxr-xr-x 2 root root 0 Nov 29 15:16 bs004.student.cs.uwaterloo.ca
drwxr-xr-x 2 root root 0 Feb 11 17:19 db2a.student.cs.uwaterloo.ca
drwxr-xr-x 2 root root 0 Nov 29 15:16 flexlm202.cscf.uwaterloo.ca
drwxr-xr-x 2 root root 0 Nov 29 15:16 mails.student.cs.uwaterloo.ca
drwxr-xr-x 2 root root 0 Nov 29 15:23 mysql070.student.cs.uwaterloo.ca
drwxr-xr-x 2 root root 0 Nov 29 15:16 postgres060.student.cs.uwaterloo.ca
drwxr-xr-x 2 root root 0 Nov 29 15:16 postgres060.student.cs.uwaterloo.ca
drwxr-xr-x 2 root root 0 Nov 29 15:16 region.student.cs.uwaterloo.ca

Get information about a container

• lxc-info --name <container name>

a running system

root@mc-cloud002-n1:# lxc-info --name  mails.student.cs.uwaterloo.ca
state:   RUNNING
pid:      8331

a stopped system

root@mc-cloud002-n1:# lxc-info --name db2a.cloud.cs.uwaterloo.ca
state:   STOPPED
lxc-info: 'db2a.cloud.cs.uwaterloo.ca' is not running

Accessing the console

• lxc-console --name <container name>

root@mc-cloud002-n1:# lxc-console --name mails.student.cs.uwaterloo.ca

Type <Ctrl+a q> to exit the console

Ubuntu 12.04 LTS mails tty1

mails login: 

   lxc-attach

• You can also use 'lxc-attach --name <container name>' if you don't know the root password
  • If you are in the habit of accessing containers via ssh, lxc-attach will allow you access (as super-user on the containing host) if sshd did not start on the container (or is not even installed)