[ notes to myself ]

Deploy microk8s+microceph cluster on Debian 12

4 min read

Specifically for installing on my 3-node Zima Blades cluster

Prep

Storage

Carve out space on external drive to store snap data, and create a blank partition to use as ceph OSD

# /dev/sda1 for snap storage
# /dev/sda2 as OSD
sudo parted /dev/sda -s -a optimal -- \
  mklabel gpt \
  mkpart primary 1MiB 100GiB \
  mkpart primary 100GiB 100%

Create LVM stuff

sudo pvcreate /dev/sda1 # "y" if prompted to overwrite ext4 signature
sudo vgcreate ext /dev/sda1 
sudo lvcreate -L 20G -n snaplib ext
sudo mkfs.ext4 /dev/ext/snaplib
echo "/dev/mapper/ext-snaplib /var/lib/snapd ext4 defaults 0 2" \
  | sudo tee -a /etc/fstab
sudo lvcreate -L 20G -n snap ext
sudo mkfs.ext4 /dev/ext/snap
echo "/dev/mapper/ext-snap /var/snap ext4 defaults 0 2" \
  | sudo tee -a /etc/fstab
sudo mount -a
sudo systemctl daemon-reload

Networking

Only have a single NIC on these bad boys so can’t do really fancy stuff, but want to at least make sure the IPs don’t change:

In /etc/network/interfaces:

auto lo
iface lo inet loopback
auto enp2s0
iface enp2s0 inet static
  address 192.168.1.61 # other nodes: .62, .63
  netmask 255.255.255.0
  gateway 192.168.1.1
auto configure_network_blade1

Restart networking

sudo systemctl restart networking.service

Snaps

The handy microX tools are distributed as snaps so snap support needs to be installed

# update all the things for good measure
sudo apt-get update && sudo apt-get dist-upgrade
 
sudo apt-get install snapd
 
sudo reboot # to make sure all the snap components get registered
 
sudo snap install snapd # to update snapd to the version required by microk8s

To be able to run snaps with sudo, you may need to sudo visudo and add /snap/bin to the secure_path line in /etc/sudoers.

Microceph

Initial setup

Install

sudo snap install microceph
sudo snap refresh --hold microceph

Create cluster (on first node)

# bootstrap
sudo microceph cluster bootstrap
 
# add other nodes
sudo microceph cluster add blade2
sudo microceph cluster add blade3

Copy the token generated by the cluster add command, execute on the other nodes

sudo microceph cluster join $token

Disks

On all three

sudo microceph disk add /dev/sda2

On one

sudo ceph osd pool create cephfs_meta
sudo ceph osd pool create cephfs_data
sudo ceph fs new cephFs cephfs_meta cephfs_data

CephFS share

Not needed for k8s functionality, but nice-to-have if you’d like to access cephfs files from outside

On all three

sudo apt-get install ceph-common 
cd /var/snap/microceph/current/conf
sudo ln -s $(pwd)/ceph.conf /etc/ceph/ceph.conf
sudo ln -s $(pwd)/ceph.keyring /etc/ceph/ceph.keyring
 
sudo mkdir /cephfs 
sudo mount -t ceph :/ /cephfs/ -o name=admin,fs=cephFs
 
# verify
df -h /cephfs

Microk8s

Install

On all nodes:

sudo snap install microk8s --classic
sudo snap refresh --hold microk8s
 
# add user to microk8s group
sudo usermod -a -G microk8s john
# create ~/.kube
mkdir -p ~/.kube
# reload group membership
newgrp microk8s

Cluster bootstrap

On first node:

microk8s add-node # repeat for each node

Copy join command, run on other nodes. ex:

microk8s join 192.168.1.61:25000/92b2db237428470dc4fcfc4ebbd9dc81/2c0cb3284b05

Check out new membership:

microk8s kubectl get nodes
#> NAME     STATUS   ROLES    AGE    VERSION
#> blade1   Ready    <none>   108m   v1.32.3
#> blade2   Ready    <none>   100m   v1.32.3
#> blade3   Ready    <none>   27m    v1.32.3

Convenience aliases

echo "alias kubectl='microk8s kubectl'" >> ~/.bashrc
echo "alias k='microk8s kubectl'" >> ~/.bashrc
source ~/.bashrc
 
k get nodes # so much more convenient!
#>  NAME     STATUS   ROLES    AGE   VERSION
#>  blade1   Ready    <none>   16h   v1.32.3
#>  blade2   Ready    <none>   13h   v1.32.3
#>  blade3   Ready    <none>   13h   v1.32.3

Configure storage

# enable
microk8s enable rook-ceph
 
# connect to microceph cluster
sudo microk8s connect-external-ceph

Test-create block and filesystem PVCs ceph-pvcs.yaml

---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: ceph-fs-pvc
  namespace: default
spec:
  storageClassName: cephfs
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 1Gi
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: ceph-rbd-pvc
  namespace: default
spec:
  storageClassName: ceph-rbd
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
---

Deploy:

k apply -f ceph-pvcs.yaml
#> persistentvolumeclaim/ceph-fs-pvc created
#> persistentvolumeclaim/ceph-rbd-pvc created
 
 
k get pvc
#> NAME           STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   VOLUMEATTRIBUTESCLASS   AGE
#> ceph-fs-pvc    Bound    pvc-467d33e2-5067-4f6f-8586-46d645421cd5   1Gi        RWX            cephfs         <unset>                 3s
#> ceph-rbd-pvc   Bound    pvc-9655944b-e6b8-431b-b55c-82eac881ba04   1Gi        RWO            ceph-rbd       <unset>                 3s
 
k get pv
#> NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                  STORAGECLASS   VOLUMEATTRIBUTESCLASS   REASON   AGE
#> pvc-467d33e2-5067-4f6f-8586-46d645421cd5   1Gi        RWX            Delete           Bound    default/ceph-fs-pvc    cephfs         <unset>                          5m12s
#> pvc-9655944b-e6b8-431b-b55c-82eac881ba04   1Gi        RWO            Delete           Bound    default/ceph-rbd-pvc   ceph-rbd       <unset>                          5m12s

Load balancer

Microk8s makes it incredibly easy to deploy a reliable load balancer right in the cluster so you can expose services without having to use NodePorts.

microk8s enable metallb

Then just input your desired IP range(s) when prompted. Boom, done.