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Marc Diaz


## Prerequisites
- Have a k3s cluster with one master node and at least one control node
- Have helm installed

1. On the master node

```bash
sudo apt update
sudo apt install nfs-kernel-server -y
```
1. create and export directory
```bash
sudo mkdir -p /srv/nfs/k3s
sudo chown nobody:nogroup /srv/nfs/k3s
sudo chmod 777 /srv/nfs/k3s
```
edit `/etc/exports` to allow access:
```bash
/srv/nfs/k3s *(rw,sync,no_subtree_check,no_root_squash)
```

```bash
sudo exportfs -a
sudo systemctl restart nfs-kernel-server
```

1. Add Helm repo
```bash
helm repo add nfs-subdir-external-provisioner https://kubernetes-sigs.github.io/nfs-subdir-external-provisioner/
helm repo update
```

1. Create the namespace
```bash
kubectl create ns nfs-provisioner
```

1. Install Provisioner
```bash
helm install nfs-subdir-external-provisioner nfs-subdir-external-provisioner/nfs-subdir-external-provisioner \
  --namespace nfs-provisioner \
  --set nfs.server=<NFS_SERVER_IP> \
  --set nfs.path=/srv/nfs/k3s \
  --set storageClass.name=nfs-client \
  --set storageClass.defaultClass=true
```

### How to check that node can access file share
```bash
ssh <control_node>
sudo mkdir -p /mnt/test-nfs
sudo mount <root_ip>:/srv/nfs/k3s /mnt/test-nfs
ls /mnt/test-nfs
# check the files show
sudo umount /mnt/test-nfs
```
Go back [home](/).


How to set up my nfs server


## What are cgroups?
Cgroups or control groups allow you to allocate resources like CPU or memory to a group of tasks. For more in depth about cgroups read [this](https://docs.kernel.org/admin-guide/cgroup-v2.html)

## Why would I want to move to cgroupv1
In my case, I wanted to run judge0 on Amazon Linux 2023 but saw this [issue](https://github.com/judge0/judge0/issues/325)

### Disabling on Ubuntu
```
sudo nano /etc/default/grub
# edit this line, and save:
GRUB_CMDLINE_LINUX="systemd.unified_cgroup_hierarchy=0"
sudo update-grub
sudo reboot
```

### Disabling on Amazon Linux
Instead of manually editing the config, I used an EC2 launch template that would create my EC2 instances with cgroupsv1 enabled by default

#### Steps:
- Navigate to EC2 -> Launch Templates
- Pick an Amazon Linux AMI of your choice
- In Advanced details -> User Data paste this in
```
#!/bin/bash
grubby --update-kernel=ALL --args="systemd.unified_cgroup_hierarchy=0"
```

Go back [home](/).


cgroupsv2 might not be compatible with some software packages so this tutorial helps disable that