Ejabberd server setup via Terraform & Packer

Spinning up EC2 instances utilizing Terraform with ejabberd 17.01 installed and running along with a cluster if the setup was made with multiple instances. Basically, automating the setup process for a faster maintenance.

Setup steps

Packer creates an initial ami base to install ejabberd servers. Sample packer run:

packer validate create_image.json
packer build create_image.json

Terraform installs and forms a cluster of ejabberd servers. Needed parameters and a sample run:

-var admin_ejabberd : Your ejabberd server's admin username of your choice.
-var pass_ejabberd : Your ejabberd server's admin password of your choice.
-var instance_count : The number of nodes you'll have in your cluster.
-var erlang_cookie : Erlang cookie functioning as a password between nodes. Preferably long and random.
-var access_key : Your AWS access key.
-var secret_key : Your AWS secret key.
-var region : AWS region.
(optional) -var ami : The ami of your instances can be set via this variable. Default value: ami-8c3beef6. The image is created by a packer/create_image.json run and is sufficient for ejabberd clustering.
-var ejabberddomain : The domain of the node. Default value: localhost.

terraform apply \
-var 'admin_ejabberd=YOUR_ADMIN_USERNAME' \
-var 'pass_ejabberd=YOUR_ADMIN_PASSWORD' \
-var 'instance_count=1' \
-var 'erlang_cookie=ERLANG_COOKIE_FOR_CLUSTERING' \
-var 'access_key=YOUR_AWS_ACCESS_KEY' \
-var 'secret_key=YOUR_AWS_SECRET_KEY' \
-var 'region=us-east-1' \
-var 'ami=YOUR_AMI' \
-var 'ejabberddomain=CUSTOM_DOMAIN_NAME'

After Terraform has finished, you can access your ejabberd's admin panel from your server's public ip's 5280 port: SERVER_PUBLIC_IP:5280/admin with your ejabberd credentials: admin_ejabberd@ejabberddomain pass_ejabberd.

How to add a new node to the cluster?

By setting your 'instance_count' parameter to any number bigger than 1! Terraform will handle the rest by provisioning. When you increase the instance count in the cluster, new_terra_setup.sh runs to download ejabbberd 17.01. It is installed by the parameters you've given.
After you have a node that is started by new_terra_setup.sh, cluster_setup.sh script runs to add the particular node to the running cluster. In cluster_setup.sh, the variables that keep the IPs of the nodes are formatted in the form that can be joined to a cluster directly.

Code below is run in cluster_setup.sh and does the following so that it's in the proper form for a join operation:
ip-xxx.xxx.xxx.xxx -> ip-xxx-xxx-xxx-xxx

export temp_ip=`echo ip-$temp_ip | tr  '.'  '-'`
export ejabberd_cluster_ip=`echo ejabberd@$cluster_ip | tr  '.'  '-'`

How to remove a node from the cluster?

By simply decreasing the 'instance_count' parameter to a value that is smaller than its previous value. Or if you want to destroy the whole cluster, you can use the destroy option of Terraform.

Points requiring manual change in the code

• AWS credentials in packer/create_image.json -> "AWS_ACCESS_KEY HERE" and "AWS_SECRET_KEY HERE"
• Key name that should be provided from AWS (for resource "aws_instance" "ejabberdnode" in terraform/main.tf) -> "YOUR_AWS_KEYNAME"
• Path to private key files (.pem) for the connections of the null_resources in terraform/main.tf. -> "YOUR.PEM"