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Highly available, fault tolerant pine64 cluster

The topology contains 5 Pine A64's:

  • 2 HAProxy load balancers running in Docker containers, one active and one passive.
  • Keepalived heartbeat for failover and health checks. It is installed directly onto the two load balancers, outside of the containers.
  • 3 application servers, which are round-robinned across by the active load balancer.

Haproxy

Contains the Dockerfile and config file for HAProxy (arm64). Three app servers on three different pine64's are load balanced across using the round robin algorithm.

Keepalived

Contains two Keepalived configuration files for the active load balancer and the passive load balancer respectively. The virtual ip of both must be identical for failover.

The script contained in the config files (killall -0 haproxy) sends a signal to the haproxy process to check whether it is running or not.

Note: ensure that killall is available by installing the psmisc toolkit:

sudo apt-get install psmisc

Nginx

Contains a Dockerfile for the arm64 nginx server and three slightly different variants of the same simple static web page (nice for debugging).

Ansible

Contains ansible roles for:

  • Updating & upgrading ubuntu
  • Installing software dependencies like Docker and Keepalived
  • Starting docker
  • Building and launching the docker containers for the servers and the load balancers
  • Configuring Keepalived

Configuring Ansible on the pines

  • To avoid typing passwords each time, copy the contents of your SSH key ~/.ssh/id_rsa.pub to a file in each device called ~/.ssh/authorized_keys.
  • Make sure Python is installed on each (Python is an Ansible dependency):
sudo apt-get install -y python
  • Make a new file called overrides or myOverrides in the sudoers.d directory:
sudo visudo -f /etc/sudoers.d/myOverrides

and add a new line for the ubuntu user:

ubuntu ALL=(ALL:ALL) ALL
  • Use Ansible's Ping module to verify connectivity:
ansible -m ping all

Testing on Localhost

The docker-compose file is included for simpler testing on localhost.

Make sure to change the servers in the haproxy.cfg file and uncomment the non-arm64 base images in the nginx and haproxy dockerfiles.