Ansible is a great configuration management tool; it is simple, fast and easy to learn. In some sense, CoreOS operating system shares some of Ansible's traits. This presentation describes (in 5 minutes) how a combination of these wonderful tools looks like. We will discuss the provisioning flow of a CoreOS cluster and review some tips gathered while working with this setup in production. This presentation was presented in a "Israel AWS user group" meetup.

1. CoreOS & Ansible
(in 5 minutes)

2. Project Requirements
○ Scalable infrastructure
○ Dev/Staging/Production parity
○ If possible, all environments should be provisioned with one tool
○ Automate everything: ability to start an environment from scratch
with a push of a button

3. Available Tools/Services
○ AWS CloudFormation
○ Terraform
○ Ansible
○ Various container “hosting” services like google container engine

4. Ansible Provisioning Flow
1. Configure AWS resources (VPC,
Security groups ...) / Vagrant
2. Start the required amount of instances
3. Choose one instance as a gateway for
future cluster interactions (using
add_host module)
VPC
1 2 3
ec2 instances

5. Ansible Provisioning Flow
4. Install ansible support (https://github.
com/defunctzombie/ansible-coreos-bootstrap)
5. Run fleetctl/etcdctl commands to
schedule containers for the whole
cluster
1 2 3
ec2 instances
fleetctl/etcdctl start es@{1,2,3}

6. Observations
○ Ansible’s AWS support is still lacking basic modules (IAM roles…)
○ It is better to use Fleet / Etcd API instead of ssh / bootstrapping a
“gateway” host
○ Ansible roles and tags help to group and operate related units
together
○ Prefer containers over locally installed binaries, avoid over
configuring the coreos hosts
○ Instance metadata can help in isolating critical container resources