Ansible

For the examples we consider the following hosts file:

[controllers]
node1 ansible_host=10.0.1.214

[computes]
node2 ansible_host=10.0.3.140
node3 ansible_host=10.0.0.200

Run a command on specific hosts (no python required)

run ls command on all computes that are part of nodes group.

ansible -i hosts computes -m raw -a 'ls'

Note:

• -m choose the module name, raw allow to run any command
• -a for arguments to the module
• raw module does not require python on target nodes

Restart a service

ansible -i hosts -m service -a "name=slurmd state=restarted" computes

Reboot all nodes

ansible --become --user ubuntu -i environments/prod1/hosts all --module-name raw -a 'reboot'

Notes:

• --become is equivalent to run a sudo
• --user ubuntu will connect with the ubuntu user

Gather variables from the nodes

ansible -m setup -a gather_subset='network' -i hosts node2

Note: network can be changed by all to get all informations.

Avoid to check the host key

export ANSIBLE_HOST_KEY_CHECKING=False

Run a playbook locally

ansible-playbook --connection=local --inventory 127.0.0.1, --limit 127.0.0.1 playbook.yml -i ansible_hosts

Passing variables through cli

--extra-vars "version=1.23.45 other_variable=foo"