Example of using Terraform with Ansible-deployed Cassandra DB using ansible-cassandra.

NB: This is for teaching purposes only and is NOT intended as a production deployment.

Deployment Host Setup

The host we're using for the workshop already has several things set up:

• git, python, pip, virtualenv, wget and unzip installed.
• A virtualenv at ~/venv which has openstacksdk and ansible installed.
• terraform installed.
• An openstack rc file and a ~/.config/openstack/clouds.yaml file to authenticate against openstack.
• Ansible galaxy roles downloaded to ~/.ansible/roles
• An ssh keypair at ~/.ssh/id_rsa{.pub}.

To avoid treading on other's work, create your own directory and work in that:

cd
. ~/venv/bin/activate   # makes openstack and ansible available
mkdir <yourname>
cd <yourname>
git clone https://github.com/stackhpc/tf-cassandra.git   # this repo
cd tf-cassandra

Clone the cassandra role and install its requirements into a local directory:

mkdir roles
git clone https://github.com/wireapp/ansible-cassandra.git roles/ansible-cassandra
ansible-galaxy install --roles-path roles/ -r roles/ansible-cassandra/molecule/default/requirements.yml

Modify the cassandra role to fix a missing package:

• Edit roles/ansible-cassandra/defaults/RedHat.yml
• Change jemalloc to memkind.x86_64

Install terraform:

cd
wget https://releases.hashicorp.com/terraform/0.12.24/terraform_0.12.24_linux_amd64.zip
unzip terraform*.zip
sudo cp terraform /bin # or ~/.bin or wherever is on your path

Create a clouds.yaml file with your credentials for the Openstack project to use - see clouds.yaml.example if necessary.

Deployment and Configuration

1. In group_vars/all.yml, change instance_prefix to your name.

2. Deploy infrastructure using Terraform:

    terraform init
    terraform plan
    terraform apply
   

   This will generate a file ./inventory.

3. Install and configure software using Ansible:

    . ~/venv/bin/activate
    ansible-playbook -i inventory install.yml
   

4. To log in to the cluster use:

    ssh centos@<ssh_proxy>
   

   where ssh_proxy is given in the inventory.

To destroy the cluster when done:

terraform destroy

Usage

The role configures Cassadnra's cqlsh CLI tool to connect to the clsuter automatically. So you can log in to a node (as described above) then just run:

cqlsh

See https://cassandra.apache.org/doc/latest/tools/cqlsh.html for reference.