Now that you have your Stack of NUCs all built, updated, and connected to the wireless network, it is time to set them all up in the Ansible inventory so we can start doing things with them.

Purpose:

• Discover local hosts that the Ansible control node can access
• Add these hosts to our inventory

Steps:

1. power on all the nodes
2. run the discovery script from the Ansible control node (NUC 2), and add the IP address to the inventory file ('hosts')
   • example:
     • cd my-project
     • bash discover.sh hosts

   • discover.sh

     if [ "$#" -ne 1 ]
     then
       echo "Usage: $0 filename.txt"
       echo "results will be appended to this file"
       exit 1
     fi
     OUTPUT=$1
     [[ ! -z "$OUTPUT" ]] && touch $OUTPUT || exit
     IPs=$(sudo arp-scan --localnet --numeric --quiet --ignoredups | grep -E '([a-f0-9]{2}:){5}[a-f0-9]{2}' | awk '{print $1}')
     for i in ${IPs}; do
       # set up SSH managment keys
       ssh-keygen -q -R $i && ssh-keyscan -H $i >> ~/.ssh/known_hosts
       # identify hosts ansible can access
       ssh -q -o PasswordAuthentication=No $i "hostname -I" && echo $i && echo $i >> $OUTPUT
     done

3. to identify nodes that weren't discovered
   • ''ansible -i hosts all -a “poweroff”
   • any NUCs still powered on were not discovered properly
     • you can pull these for re-imaging/investigation, then power the “good” NUCs back on

You now have a working Ansible environment! Continue to First Ansible Job - Update