# User Data

User data, cloud init data or cloud data is a way of giving data to an instance for it to run as part of the startup process. This page will describe how to craft a cloud init script to suit your cluster.

This script would be given to the compute nodes of a multinode cluster to make setup easy. It allows the login node to find the compute nodes as long as they are on the same network, and ssh into them from the root user (which is necessary for setup).

#cloud-config
users:
  - default    
  - name: root
    ssh_authorized_keys:
      - <Content of ~/.ssh/id_alcescluster.pub from root user on login node>

One thing to note is that with this data all nodes on the network will pick up the compute node being launched, so other users could hijack your compute node.

• SERVER=<local ip of server> - Sets the ip address that this node will send to, and does a send on startup to the ip address. This is where flight hunter send will go if no ip address argument is provided. (conflicts with BROADCAST_ADDRESS)
• BROADCAST_ADDRESS=<ip range> - The node will broadcast its information across an ip range. (conflicts with SERVER)
• AUTH_KEY=<password> - Sets an auth key that is used by flight hunter hunt and flight hunter send.
• LABEL=<nodename> - Sets label to be sent with flight hunter.
• PREFIX=<nodeprefix> - Sets prefix for flight hunter send.
• AUTOPARSEMATCH=<node> - Sets the regex for auto-parse rules in the hunter server. It also makes the hunter server automatically parse hunted nodes. (must be passed to your login node)
• SHAREPUBKEY=true - If set to true then this node will share the root user’s pub ssh key over network on port 1234. This means that any solo images with SERVER set to this node will attempt to grab its public key.

#cloud-config
write_files:
  - content: |
      SERVER=10.50.0.43
      BROADCAST_ADDRESS=10.50.255.255
      AUTH_KEY=banana
      LABEL=<nodename>
      PREFIX=<nodeprefix>
      AUTOPARSEMATCH=<node>
      SHAREPUBKEY=true
    path: /opt/flight/cloudinit.in
    permissions: '0644'
    owner: root:root
users:
  - default    
  - name: root
    ssh_authorized_keys:
      - <Content of ~/.ssh/id_alcescluster.pub from root user on login node>