Linux-cluster-test-ansible

Linux-cluster-test-ansible is a Vagrant environment test for Linux cluster based on Pacemaker and Corousync using pcs CLI interface. It use Ubuntu 1804 lts+, Centos 7 or AmlaLiux 8+ vm.

It is based on the Linux-cluster-test project which, however, did not use ansible.

Installation

mkdir linux-cluster-test-ansible
cd linux-cluster-test-ansible
git clone https://github.com/eniocarboni/linux-cluster-test-ansible .
cp provision/vars/cluster_password.TMPL.yml provision/vars/cluster_password.yml
ansible-galaxy collection install -r provision/requirements.yml

# edit provision/vars/cluster_password.yml and change the 3 password to secure installation

Based on your needs you may want to create an encrypted ansible-vault containing the passwords from the provision/vars/cluster_password.yml file. This way ansible will ask you to enter your password each time to open the vault:

ansible-vault encrypt provision/vars/cluster_password.yml
sed -i 's/#ansible.ask_vault_pass/ansible.ask_vault_pas/' Vagrantfile

Check configuration variables in provision/vars/cluster.yml

Use

First, check the Vagrant file to see $BOX variable. by default use ubuntu/focal64 (Ubuntu 20.04 LTS) and 3 cluster node and a simple fence ssh agent (see https://github.com/nannafudge/fence_ssh).

vagrant up --provision

Add new nodes to cluster

You can add a node by changing the variable $NUM_CLUSTER_NODES in Vagrant file, for example from 3 to 4. At this point you just need to relaunch "vagrant up && vagrant provision" or

vagrant up --provision

Remove a node from cluster

Suppose we start with the default cluster with 3 nodes. To decrease the cluster by one node you must:

• launch "vagrant destroy cl-node-3"
• update the Vagrantfile by decreasing the $NUM_CLUSTER_NODES variable by one (put it at 2)
• launch "vagrant up --provision"

Restoring a node for problems

Suppose we want to restore a problematic node, for example node 2:

• launch "vagrant destroy cl-node-2"
• launch "vagrant up --provision"

Provision with ansible

We could directly use ansible for the "provision" instead of vagrant:

ansible-playbook --inventory-file=.vagrant/provisioners/ansible/inventory/vagrant_ansible_inventory provision/playbook.yml

In this way we could take advantage of tags with ansible:

ansible-playbook --inventory-file=.vagrant/provisioners/ansible/inventory/vagrant_ansible_inventory --tags="fence" provision/playbook.yml
# or 
ansible-playbook --inventory-file=.vagrant/provisioners/ansible/inventory/vagrant_ansible_inventory --tags="controller" provision/playbook.yml

Notes on operation

Note about the cluster resources created

The provision scripts create 4 cluster resources groupped in 3 resources:

• group apachegroup:
  • resource first_test_ip (ocf::heartbeat:IPaddr2)
  • resource Web1 (ocf::heartbeat:apache)
• group group_second_test_ip
  • resource second_test_ip (ocf::heartbeat:IPaddr2)
• group group_last_test_ip
  • resource last_test_ip (ocf::heartbeat:IPaddr2)

View resources in provision/vars/cluster.yml

If fence_agent is true the provision scripts create one fence resource for each node:

• stonith-ssh-1 (for node 1)
• stonith-ssh-2 (for node 2)
• stonith-ssh-3 (for node 3) and a constraint resource for each fence resource so that to not start in the same node relative to the fence:
• stonith-ssh-1 not start on node 1
• stonith-ssh-2 not start on node 2
• stonith-ssh-3 not start on node 3

View fence_agent in provision/vars/cluster.yml

You may set fence_agent: false to remove all stonith resources and remove 3rd network interface and all refering to fence

Note on firewall

On RedHat family box use firewalld while on Ubuntu/Debian use ufw

COPYRIGHT

Copyright (c) 2022 Enio Carboni - Italy

This file is part of Linux-cluster-test-ansible.

Linux-cluster-test-ansible is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

Linux-cluster-test-ansible is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with Linux-cluster-test. If not, see http://www.gnu.org/licenses/.