Juju 2.0~ Local LXD provider workflows are awesome!

[Antonio Rosales]

On Wed, Feb 3, 2016 at 1:09 PM, James Page <james.page at ubuntu.com> wrote:
> Hi All
>
> I've been using Juju 2.0 (built from source with an in-flight patch for LXD
> 2.0 right now - but that should be resolved soon) with the local LXD
> provider on Ubuntu Xenial development to test some work we've been doing to
> get OpenStack running on-top of LXD in a single machine.
>
> That's now working quite well (a few rough edges), but is not the main topic
> for my post.

This is solid, thanks for sharing here.

-Antonio

>
> 1) Multiple models, single controller
>
> Alongside LXD support, you can also create multiple models against a single
> controller, so I've been creating models to deploy, test and review specific
> pieces of work (reviewing the midonet charms right now for example):
>
>   juju bootstrap
>   juju create-model midonet-review
>   juju switch midonet-review
>
> .... and then deploy away;  Not having to re-bootstrap a controller
> every-time I want to tear-down and redeploy, or push something new up for
> test optimizes my workflow nicely.
>
> 2) Tweaking container profiles
>
> For each model, Juju creates a profile in LXD (named juju-<model name>)- and
> its quite possible to make additions to that profile for your specific model
> requirements - here's the one we wrote for openstack-on-lxd:
>
> name: juju-openstack-on-lxd
> config:
>   boot.autostart: "true"
>   linux.kernel_modules: openvswitch,nbd,ip_tables,ip6_tables
>   security.nesting: "true"
>   security.privileged: "true"
> devices:
>   eth0:
>     mtu: "9000"
>     name: eth0
>     nictype: bridged
>     parent: lxcbr0
>     type: nic
>   eth1:
>     mtu: "9000"
>     name: eth1
>     nictype: bridged
>     parent: lxcbr0
>     type: nic
>   kvm:
>     path: /dev/kvm
>     type: unix-char
>   root:
>     path: /
>     type: disk
>   tun:
>     path: /dev/net/tun
>     type: unix-char
>
> This adds a-lot to the default profile, but at a high level ensures that
> each container gets two network interfaces with a high mtu to avoid packet
> fragmentation, can access a few devices required for virt networking and
> process management - and also switches the container into 'privileged' mode
> that we need for Open vSwitch support in a container right now (Tycho is
> working on fixing that so we can run unprivileged).  Read more about LXD
> profiles here:
>
>   https://github.com/lxc/lxd/blob/master/specs/configuration.md
>
> Editing is super easy - 'lxc profile edit <profile-name>'.
>
> 3) Pause/Resume containers
>
> I've found a few bits that LXD provides outside of Juju quite useful as well
> - specifically I've been away from regular power for the last few days, so
> I've been using the 'pause' feature of containers to freeze containers,
> stopping CPU consumption and making my battery last a alot longer without
> destroying and re-deploying the environment (which would consume far more
> battery anyway) - here's 'pause-juju':
>
>   for container in `lxc list | grep RUNNING | grep juju | awk '{ print $2
> }'`; do
>       lxc pause $container
>   done
>
> and 'resume-juju':
>
>   for container in `lxc list | grep FROZEN | grep juju | awk '{ print $2
> }'`; do
>       lxc start $container
>   done
>
> I'm doing this outside of Juju right now - but I think it would make a great
> feature!
>
> All container processes still consume memory, but stop consuming cpu cycles
> until resumed.
>
> Oh - and use the ZFS backend for LXD - its superfast!:
>
>
> https://insights.ubuntu.com/2015/11/06/using-lxd-with-a-file-based-zfs-pool-on-ubuntu-wily/
>
> Hope people find that all useful!
>
> Cheers
>
> James
>
>
>
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-- 
Antonio Rosales
Ecosystem Engineering
Canonical