http://genevajug.ch/events/2016-02-23-ansible.html
- Linux machine running on EC2 with Ansible
- SSH key named "ansible_ec2_key.pem"
- copy the SSH key to "/etc/ansible/ssh/ansible_ec2_key.pem"
In this demo, we have a look at Amazon EC2 configuration to create Security Group and EC2 instances thanks to Ansible.
# Presentation of the host file with some groups but no host
nano hosts
ansible --list-hosts all
# Provision 2 instances
ansible-playbook playbooks/ec2_provision.yml
In this demo, we walk through basic concepts of Ansible and core Configuration principles:
-
Static inventory to declare hosts of the demo
-
Patterns to select hosts with
ansible --list-hosts- host name or group name
- mix of groups (union, intersection)
- wildcard
- regex
-
Ops Hello World with
ansible -m ping -
Gather Ansible facts (data from remote machines) with
ansible -m setup -
Test basic ad-hoc commands with
ansible -m shell -
Idempotence principle by executing the same command twice
-
Configuration Drift leading to Snowflake servers by uninstalling a package rather than reprovisioning from scrath with Phoenix servers
# navigate through the inventory
nano hosts
ansible --list-hosts all
ansible --list-hosts ec2_hosts
ansible --list-hosts 'all:!local'
ansible --list-hosts 'ec2_hosts:other_hosts'
# check connectivity at host level
ping <host>
# check connectivity at ansible level
ansible -m ping ec2_hosts
ansible -m shell -a "uptime" ec2_hosts
ansible -m setup <host>
ansible -m setup -a "filter=ansible_eth[0-2]" ec2_hosts
# install ntp package with basic configuration
ansible -m apt -a "name=ntp state=latest force=yes update_cache=yes" --sudo <host>
ssh -i ./ssh/ansible_ec2_key.pem ubuntu@<host>
nano /etc/ntp.conf
exit
# same command executed a second time, nothing changes
ansible -m apt -a "name=ntp state=latest force=yes update_cache=yes" --sudo <host>
# remove the ntp package, but the "libopts" remains on the machine
ansible -m apt -a "name=ntp state=absent" --sudo <host>
In this demo, we walk through automation concepts of Ansible:
-
Playbooks to express the sequence of tasks to obtain the "desired state"
-
Variables associated to hosts and groups
-
Jinja2 templates to generate the configuration
-
host-contextual variables with
ansible -m debug "var=hostvars['<host>']" localhost -
playbook tags to execute it partially
# script to install the NTP package and configure it thanks to a Jinja2 template
nano playbooks/ntp_template.yml
# NTP configuration template, which is a Ansible-managed file
nano playbooks/templates/ntp.conf.j2
# re-open the playbook to move the variables in the "group_vars/all.yml" (much better !)
nano playbooks/ntp_template.yml
###
ntp_hosts:
- 0.ubuntu.pool.ntp.org
- 1.ubuntu.pool.ntp.org
- 2.ubuntu.pool.ntp.org
- 3.ubuntu.pool.ntp.org
###
nano group_vars/all.yml
###
ntp_hosts:
- 0.ubuntu.pool.ntp.org
- 1.ubuntu.pool.ntp.org
- 2.ubuntu.pool.ntp.org
- 3.ubuntu.pool.ntp.org
###
# look at variables depending on the host - same config
ansible -m debug -a "var=hostvars['localhost']" localhost
ansible -m debug -a "var=hostvars['<host>']" localhost
# changes variables for the host group "ec2_hosts"
nano group_vars/ec2_hosts.yml
ntp_hosts:
- 0.ch.pool.ntp.org
- 1.ch.pool.ntp.org
- 2.ch.pool.ntp.org
- 3.ch.pool.ntp.org
# look at variables depending on the host - different configs
ansible -m debug -a "var=hostvars['localhost']" localhost
ansible -m debug -a "var=hostvars['<host>']" localhost
# execute the NTP playbook
ansible-playbook playbooks/ntp_template.yml --extra-vars "target=ec2_hosts"
# connect remotely and check the deployed configuration
ssh -i ./ssh/ansible_ec2_key.pem ubuntu@<host>
nano /etc/ntp.conf
exit
# uncomment the "uninstall" task
nano playbooks/ntp_template.yml
# use tags to execute the uninstallation, with the same playbook used for installation
ansible-playbook playbooks/ntp_template.yml --extra-vars "target=ec2_hosts" --tags "uninstall"
# terminate EC2 instances
ansible-playbook -i hosts playbooks/ec2_terminate.yml --extra-vars "target=ec2_hosts"
# check that hosts are removed from the host file
nano hosts
React
Typescript
Django
Laravel
Facebook
Microsoft
Google
Alibaba
D3
Tencent