Random Adhoc Commands

This is a collection of random adhoc commands that I have found useful.

Restart a service

ansible all -i ../terraform_ddp/inventory.yml -b -m service -a 'name=sshd state=restarted'

Change DNS Server

This was used on a set of Almalinux servers to change the DNS server to a local DNS server, since the packer/terraform setup did not set the DNS server correctly on all nodes.

export ANSIBLE_SSH_ARGS="-F ../terraform_ddp/ssh.cfg"
ansible all -i ../terraform_ddp/inventory.yml -b -m shell -a ' \
UUID=$(nmcli -t -f NAME,UUID,DEVICE,ACTIVE c show --active | grep ens | cut -d: -f2) && \
nmcli con modify "$UUID" ipv4.dns "<IP>" ipv4.ignore-auto-dns yes && \
nmcli con up "$UUID"'

Caution

Whitespace before the first command results in an error. So UUID=... must not be indented.

Validate root login via ssh

ansible all -i ../terraform_ddp/inventory.yml -b -m shell -a "\
grep -E '^PermitRootLogin' /etc/ssh/sshd_config || echo 'PermitRootLogin not set'"

Enable root login via ssh

ansible all -i ../terraform_ddp/inventory.yml -b -m lineinfile -a '
path=/etc/ssh/sshd_config
regexp="^PermitRootLogin"
line="PermitRootLogin yes"
create=yes
'