I have a MAAS cluster at home to test out Juju, OpenStack, Kubernetes etc. The cluster is really a collection of machines that have been carefully selected for their cheapness and ability to fit in a small space under a spiral staircase. Since its inception I have used an old laptop with a broken screen as a Juju controller. Unfortunately the laptop did not take kindly to having tea spilt on it a few months ago and so I forced to replace it. I was feeling flush at the time to decided to go for a Raspberry Pi 4. Unfortunately I failed to spot that the Raspberry Pi 4 does not actually network boot like a conventional machine and so I wouldn't be able to enlist it in MAAS. Fortunately while working on something else I spotted that Juju has introduced the idea of Managing multiple clouds with one controller This gave me the idea of setting up a controller on the Pi and then adding MAAS as an additional cloud to it.
Prepare the Pi
Burn an Ubuntu image onto the SD card, I went for the Ubuntu 20.04.1 64-bit
server OS for arm64. Give the Pi a static IP address. I haven't tested it but
I'm sure the Pi needs to have a wired network connection rather than wireless,
otherwise access to containers via the macvlan interface will break.
I believe it would be possible to set the controller up using the Manual cloud type but I prefer the idea of the controller being in its own LXD container
so I went for that approach. To configure LXD initialise it and then disable
ipv6 as it doesn't currently work with Juju.
ubuntu@pi-controller-host:~$ lxd init --auto ubuntu@pi-controller-host:~$ lxc network set lxdbr0 ipv6.address none
The controller needs to have access to the network the MAAS nodes are going to
be deployed on. The primary interface on the LXD containers could be switched
to be macvlan rather than bridged but unfortunately for reasons the LXD host
would loose access to the containers. A neat solution is to give the LXD
container two nics, one on the bridged network which will allow the host
(pi-controller-host in my case) access to the containers and one macvlan
interface that will give the wider network access to the containers.
This Pi is only going to be used as a controller so I make these network
changes in the default lxd profile.
ubuntu@pi-controller-host:~$ cat two-nics.yaml
config:
user.network-config: |
version: 1
config:
- type: physical
name: eth0
subnets:
- type: dhcp
ipv4: true
- type: physical
name: eth1
subnets:
- type: dhcp
ipv4: true
description: Default LXD profile
devices:
eth0:
name: eth0
network: lxdbr0
type: nic
eth1:
name: eth1
nictype: macvlan
parent: eth0
type: nic
root:
path: /
pool: default
type: disk
name: default
ubuntu@pi-controller-host:~$ lxc profile edit default < two-nics.yaml
Install Juju Controller
Install the juju client. In this case I needed to do some testing with Juju
2.8.2 so I went for the candidate channel but normally I'd go for the
latest/stable channel.
ubuntu@pi-controller-host:~$ sudo snap install --classic --channel=2.8/candidate juju juju (2.8/candidate) 2.8.2 from Canonical✓ installed
Next create the Juju controller.
ubuntu@pi-controller-host:~$ juju bootstrap localhost pi-lxd-controller
Creating Juju controller "pi-lxd-controller" on localhost/localhost
Looking for packaged Juju agent version 2.8.2 for arm64
No packaged binary found, preparing local Juju agent binary
To configure your system to better support LXD containers, please see: https://github.com/lxc/lxd/blob/master/doc/production-setup.md
Launching controller instance(s) on localhost/localhost...
- juju-b84c1e-0 (arch=arm64)
Installing Juju agent on bootstrap instance
Fetching Juju Dashboard 0.2.0
Waiting for address
Attempting to connect to 10.119.95.251:22
Attempting to connect to 172.16.0.20:22
Connected to 10.119.95.251
Running machine configuration script...
Bootstrap agent now started
Contacting Juju controller at 10.119.95.251 to verify accessibility...
Bootstrap complete, controller "pi-lxd-controller" is now available
Controller machines are in the "controller" model
Initial model "default" added
Now the Juju controller is setup for using Juju to deploy applications into
local LXD containers. But the idea here is to use this controller for
deployments to MAAS. To achieve this we need to add the MAAS cloud to the
controller:
ubuntu@pi-controller-host:~$ juju add-cloud --controller pi-lxd-controller
Cloud Types
lxd
maas
manual
openstack
vsphere
Select cloud type: maas
Enter a name for your maas cloud: homemaas
Enter the API endpoint url: http://172.16.0.2:5240/MAAS
Cloud "" added to controller "pi-lxd-controller".
WARNING loading credentials: credentials for cloud homemaas not found
To upload a credential to the controller for cloud "homemaas", use
* 'add-model' with --credential option or
* 'add-credential -c homemaas'.
Giving the controller an api key for the MAAS environment is a separate step:
ubuntu@pi-controller-host:~$ juju add-credential --controller pi-lxd-controller homemaas Using cloud "homemaas" from the controller to verify credentials. Enter credential name: admin Regions default Select region [any region, credential is not region specific]: Using auth-type "oauth1". Enter maas-oauth: Controller credential "admin" for user "admin" for cloud "homemaas" on controller "pi-lxd-controller" added. For more information, see ‘juju show-credential homemaas admin’.
Since I opted for a candidate version of Juju I need to tell Juju where to
look for the agent code:
ubuntu@pi-controller-host:~$ juju model-defaults homemaas agent-stream=devel
Deploying to MAAS
A Juju model is specific to a cloud and at this point the controller can
deploy to two different clouds: LXD and MAAS. To differentiate between the two
when adding a model the cloud needs to be specified:
ubuntu@pi-controller-host:~$ juju add-model maas-model homemaas Added 'maas-model' model on homemaas/default with credential 'admin' for user 'admin'
I can now deploy applications using MAAS via my LXD controller on the
Pi:
ubuntu@pi-controller-host:~$ juju deploy ubuntu Located charm "cs:ubuntu-15". Deploying charm "cs:ubuntu-15". ubuntu@pi-controller-host:~$ juju status Model Controller Cloud/Region Version SLA Timestamp maas-model pi-lxd-controller homemaas/default 2.8.2 unsupported 09:05:39Z App Version Status Scale Charm Store Rev OS Notes ubuntu 18.04 active 1 ubuntu jujucharms 15 ubuntu Unit Workload Agent Machine Public address Ports Message ubuntu/0* active idle 0 172.16.0.104 ready Machine State DNS Inst id Series AZ Message 0 started 172.16.0.104 warm-dog bionic default Deployed
Accessing Controller Remotely
I tend to keep all my deployment config on the MAAS server so it makes sense to be able to administer the Juju deployment from there. To set this up I needed to create a new user with Juju and then use that use on the MAAS server.
ubuntu@pi-controller-host:~$ juju add-user fawkesadmin
User "fawkesadmin" added
Please send this command to fawkesadmin:
juju register MGwTC2Zhd2tlc2FkbWluMCgTEzVERYLONGSTRING
"fawkesadmin" has not been granted access to any models. You can use "juju grant" to grant access.
Next I need to grant that user superuser perms on the controller
ubuntu@pi-controller-host:~$ juju grant fawkesadmin superuser -c pi-lxd-controllerFinally on the maas server I can register that controller
1 liam@fawkes:~$ juju register MGwTC2Zhd2tlc2FkbWluMCgTEzVERYLONGSTRING
Enter a new password:
Confirm password:
Enter a name for this controller [pi-lxd-controller]:
Initial password successfully set for fawkesadmin.
Welcome, fawkesadmin. You are now logged into "pi-lxd-controller".
There are 3 models available. Use "juju switch" to select
one of them:
- juju switch admin/controller
- juju switch admin/default
- juju switch admin/maas-model
I now need to add the MAAS creds the fawkesadmin user is going to use (I used the same API key as before)
liam@fawkes:~$ juju add-credential -c pi-lxd-controller homemaas
Using cloud "homemaas" from the controller to verify credentials.
Enter credential name: admin
Regions
default
Select region [any region, credential is not region specific]:
Using auth-type "oauth1".
Enter maas-oauth:
Controller credential "admin" for user "fawkesadmin" for cloud "homemaas" on controller "pi-lxd-controller" added.
For more information, see ‘juju show-credential homemaas admin’.
