from Jeff Geerling's Ansible for DevOps, with some additional monkeying about by myself.
REM: test load balancing:
$ for i in {1..5}; do curl -Is http://ball.boxen.dev/ | grep Cookie; done
Set-Cookie: SERVERID=10.11.12.103; path=/
Set-Cookie: SERVERID=10.11.12.102; path=/
Set-Cookie: SERVERID=10.11.12.103; path=/
Set-Cookie: SERVERID=10.11.12.102; path=/
Set-Cookie: SERVERID=10.11.12.103; path=/
disable proxying to one of the app servers:
$ ansible-playbook playbooks/deploy.yml
confirm that it has been removed from rotation:
$ for i in {1..5}; do curl -Is http://ball.boxen.dev/ | grep Cookie; done
Set-Cookie: SERVERID=10.11.12.103; path=/
Set-Cookie: SERVERID=10.11.12.103; path=/
Set-Cookie: SERVERID=10.11.12.103; path=/
Set-Cookie: SERVERID=10.11.12.103; path=/
Set-Cookie: SERVERID=10.11.12.103; path=/