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99-extra-install.md

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Installing a more capable storage backend (optional)

The default hostpath provisioner (also in use by the other solutions) will, whenever a storage volume is needed, just take a folder on the machine you are running on. That's fine for experimenting, but will fail quickly in multi-node clusters: because these folders are not shared amongst the nodes, once created, a pod will never be able to move to another node, and you will not be able to share data between pods running on different nodes.

NFS Ganesha allows for shared (RWX) volumes by taking a system-provided volume and launching a userspace NFS server on it. Not really suitable for running production loads, but it's lightweight (only 1 pod), so ideal for the tutorial.

# need nfs utilities on the host. that's the only dependency!
sudo apt -y install nfs-common
sudo systemctl stop  portmap.service rpcbind.socket rpcbind.service
sudo systemctl disable  portmap.service rpcbind.socket rpcbind.service
cd /tmp
git clone https://github.com/kubernetes-sigs/nfs-ganesha-server-and-external-provisioner
cd nfs-ganesha-server-and-external-provisioner/charts
helm install nfs-server-provisioner nfs-server-provisioner  \
  --namespace nfs-server-provisioner --create-namespace \
  --set persistence.storageClass="local-path" \
  --set persistence.size="200Gi" \
  --set persistence.enabled=true \
  --set 'storageClass.mountOptions[0]=tcp' --set 'storageClass.mountOptions[1]=nfsvers=4.1'

Warning installing nfs-common starts two services that we don't need, and that can be a security risk when you are on an internet connected machine. So don't forget to run the following commands to disable them again:

sudo systemctl stop  portmap.service rpcbind.socket rpcbind.service
sudo systemctl disable  portmap.service rpcbind.socket rpcbind.service

If you are running a small multi-node cluster, longhorn is worth giving a try, but mind that maintaining a storage backend is a tedious task (no matter how easy the installation procedure makes it look). On a real project, you will probably use some vendor-supplied storage solution, like the one from AWS or Azure or other cloud providers. Some cloud providers that don't have a kubernetes offering, but, for instance on hetzner you can still use their volume storage with your kubernetes installation.

For an on premise solution, an easier to maintain option could be buying a (hardware) NAS that supports NFS (which is pretty much any brand nowadays) and then using a volume provider like this one to provision storage volumes from the NAS.

Automate the refresh of /etc/hosts

The following install script installs a systemd service that will auto-update /etc/hosts whenever your ip address changes.
If you use WSL, rather follow the instructions in the WSL README.

You can put the aliases you want in /etc/update_hosts_file/aliases (put them all on the same line, separated by spaces). Don't put comments in that file!

#!/bin/sh


cat << END | sudo tee /etc/systemd/system/ip-change-mon.service
# /etc/systemd/system/ip-change-mon.service

[Unit]
Description=IP Change Monitor
Wants=network.target
After=network-online.target

[Service]
ExecStart=:/bin/bash -c "ip mon addr | sed -nu -r \'s/.*[[:digit:]]+:[[:space:]]+([^[:space:]]+).*/\\1/p\' | while read iface; do systemctl restart ip-changed.target; done"

[Install]
WantedBy=multi-user.target default.target
END


cat << 'END' | sudo tee /usr/local/bin/update_hosts_file.sh
#!/bin/bash

export MYIP=$(/usr/bin/hostname -I | cut -d' ' -f1)
export ALIASES=$(cat /etc/update_hosts_file/aliases)
sed -i '/UPDATE_HOSTS_FILE/d' /etc/hosts
echo "$MYIP $ALIASES ### UPDATE_HOSTS_FILE" | tee -a /etc/hosts

END

sudo chmod u+x /usr/local/bin/update_hosts_file.sh

cat << END | sudo tee /etc/systemd/system/ip-changed.target
# /etc/systemd/system/ip-changed.target 

[Unit]
Description=IP Address changed
END

cat << END | sudo tee /etc/systemd/system/updatehosts.service
[Unit]
Description=Updates the host file to fake DNS entries.
PartOf=ip-changed.target
Before=ip-changed.target
StartLimitBurst=20
StartLimitIntervalSec=5

[Service]
Type=oneshot
ExecStart=/usr/local/bin/update_hosts_file.sh
RemainAfterExit=true

[Install]
WantedBy=multi-user.target
END

sudo mkdir -p /etc/update_hosts_file

[[ -f /etc/update_hosts_file/aliases ]] || echo "registry.kube-public" | sudo tee /etc/update_hosts_file/aliases

sudo systemctl enable --now ip-change-mon
sudo systemctl enable --now updatehosts