One Node Kubernetes Cluster

With Project Atomic on Linode

Derek Carter aka "goozbach"

Goozbach Infrastructure Solutions LLC

Why a One-Node Cluster?

• Kubernetes is an awesome new tech.
• I like to keep up on new tech.
• I needed to rebuild my personal server infrastructure.
• Why not containers?
• Why not “The Right Way”?

Getting started – Create a Linode

Create Bootstrapping OS

“Rebuild”

• 3500 M disk
• 512 M Swap
• CentOS 7
• Set root password

Create Aux Disks

• cidata volume – 100M
• image volume – Rest of space

Modify Initial Configuration Profile

• Name: bootstrapping
• Virtual Machine Mode: Full-virtualization
• Disks
  • centos – sda (leave alone)
  • swap – sdb (leave alone)
  • cidata – sdc (add this one)
  • atomic – add (add this one)

Create Atomic Configuration Profile

• Name: Atomic
• Virtual Machine Mode: Full-virtualization
• Disks
  • Atomic – sda
  • Swap – sdb
  • cidata – sdc

Boot Into Bootstrapping Profile

• Wait for system to boot, ssh into it.

Setup Bootstrapping Environment

• install needed packages
  • dosfstools – needed for mkfs.vfat
  • wget
• Download Fedora Atomic qcow2 image
  • https://getfedora.org/atomic/download/
• Create filesystem on cidata volume

OPTIONAL: ipv6 issues

put this in /etc/sysctl.d/99-noipv6.conf

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1

Create cloud-init data files

• meta-data – Machine identification
• user-data – Cloud-init configuration

meta-data

Contents:

instance-id: atomic-F329-458F-AB4E-147410BC283F
local-hostname: atomic.example.com

The field instance-id is a unique identifer for the machine. Cloud init only runs once based on instance-id.

user-data

• copy ssh host keys into user-data
  • allows for both “configuration profiles” to have the same ssh host key
• copy user ssh key
  • allows for passwordless logins
• create other users
  • if needed

#cloud-config
user: goozbach
ssh_pwauth: False
ssh_authorized_keys:
  - '<USERKEY1>'
  - '<USERKEY2>'
ssh_keys:
  rsa_private: |
    <INSERT CONTENTS HERE>

  rsa_public: <PUBKEY GOES HERE>

  ecdsa_private: |
    <INSERT CONTENTS HERE>

  ecdsa_public: <PUBKEY GOES HERE>


  ed25519_private: |
    <INSERT CONTENTS HERE>

  ed25519_public: <PUBKEY GOES HERE>

Copy cloud-init files into cidata partition

• Mount the cidata partition

• Copy meta-data and user-data files into partiion

• Unmount partition

Write images into atomic disk

Reboot into Atomic Configuration profile.

kubectl

Launch pods

Expose pods

Thank You!