Ansible Scalable and Load Balanced (SLB) Tomcat

An ansible playbook to deploy on Amazon AWS a scalable set of instances of Apache Tomcat 7 container proxied via a “load-balancing purpose” instance driven by HAProxy, as a bonus I Nagios3 on all the instance, so even an example of infrastructure monitoring is given.

So the ansible playbook will launch:

• 2 EC2 micro instances tagged as tomcat

  • Security Group with port 8080 and 22
  • Tomcat 7 installed via apt

• 1 EC2 micro instances tagged as harpoxy

  • Security Group with port 80, 8888, 1936 and 22
  • HAProxt and Socat installed via apt
  • the instance will proxy and balance (using Round-Robin strategy) from port 8888 to the Tomcat instances
  • an HAproxy amdin interface is available on port 1936

Prerequisites

• Ansible
• an account on Amazon AWS and a corresponding IAM role

Configuration

###1. AWS Credentials Export system env variables for Amazon AWS IAM role credentials like the following:

export ANSIBLE_HOST_KEY_CHECKING=False
export AWS_ACCESS_KEY_ID='AK123'
export AWS_SECRET_ACCESS_KEY='abc123'

or put the previous commands in a file (e.g. secret_iam.env) and launch form terminal:

source secret_iam.env

###2. AWS regions, vpc, subnets

Fill the configuration file under ec2/var/main.yml

keypair: <<your keipair name>>
region: us-east-1
instance_type: t2.micro
image: ami-9eaa1cf6 # Ubuntu Server 14.04 LTS (HVM), SSD Volume Type
tag_ec2_current: launched
subnets:
- subnet-fbe306d0
vpc_id: vpc-9ed752fb

All the ec2 instances will be configured starting from this file.

Running

Now you are able to launch the playbook

ansible-playbook -i ec2.py --private-key=<path_to_your_aws-pem_key ec2-lauch.yml  -v

Notes

• Templates and playbooks are massively compiled from variables yaml files. Remeber to check them before installing your inventory.

Known Issues

• Launching the playbook for the first time may fail resulting in AnsibleUndefinedVariable for some values of ec2 tags (ec2_tag_Name). Running the same for a new attempt will succeed silently.