CoreOS Tutorial 01 - Installation

I'm writing these CoreOS tutorials to document & share my experience with the platform.  In my initial dealings with Docker & CoreOS I have found the CoreOS docs to be very minimal & unsatisfactory especially for new users.

Prep for the install

These instructions show how to perform CoreOS install using the .iso method.

• Download the CoreOS .iso
• Get familiar with the cloud-config.yaml example file & gather all the values for the < your xxxx> tags within the file ( your going to need them later)
• Create a bootable CoreOS USB key or burn a CD using the .iso file
• Create your own personal SSH Keys (you'll nee the contents of the id_rsa.pub file) 
• Make sure you have an active internet connection

Now we're ready for some boot action

Install CoreOS

These directions show how to install CoreOS to a disk

• Boot to CoreOS using the bootable USB Key or CD until you see the $ core@localhost~$ prompt
• Download the cloud-config.yaml template I mentioned above:
       $ wget -O cloud-config.yaml http://bit.ly/1o2J9vA
• Get the Network Interface name:
      $ ifconfig - the nic name should be something like en... or ens...
• Use the VIM text editor to modify the cloud-config.yaml file we just downloaded.
     $ vim cloud-config.yaml
• Replace all the < your ... > tags with values pertinent to your installation, values such as Hostname, IP Address, Gateway, Public SSH Keys etc...
• Save the file with your changes.
• Now we'll install CoreOS using the core-install script:
      $ sudo coreos-install -d /dev/sda -C stable -c ~/cloud-config.yaml
• After a successful installation reboot the server & remove the boot media
• Reboot a second time for the new settings to take place

Assign Sudo Access to the cloud-config.yaml users

Unfortunately you have to manually add users to the sudoers file in order to assign root privileges.

•  Login into the new server via SSH:
      $ ssh core@<your ip address>
• $ sudo -i      to get root access
  
• Create a new sudo rule & give the user(s) sudo access (replace the < ..> with your user's name:
      $ echo "< your user's name > ALL=(ALL) NOPASSWD: ALL" > /etc/sudoers.d/< your user's name >
• Reboot the server
• Login to the server via ssh using your new user & test your sudo access

CoreOS is a very cool tool but still lacking in documentation which is usually the case with cutting edge technologies.  I'll be writing a followup blog that will discuss CoreOS & using docker to create new application containers.

Props to Stevie Holdway's blog which served we well in writing this. It's also a great resource.

Stay tuned

-a