ClusterEC2

This is an EC2 clustering strategy for libcluster. It currently supports identifying nodes based on EC2 tags.

The default Tags strategy uses ex_aws to query the EC2 DescribeInstances API endpoint. Access to this API should be granted to the EC2 instance profile. See the ExAws docs for additional configuration options.

config :libcluster,
  topologies: [
    example: [
      strategy: ClusterEC2.Strategy.Tags,
      config: [
        ec2_tagname: "elasticbeanstalk:environment-name"
      ],
    ]
  ]

Installation

The package can be installed by adding libcluster_ec2 to your list of dependencies in mix.exs:

def deps do
  [{:libcluster_ec2, "~> 0.5"}]
end

AWS IAM Requirements

Instances must have an instance role attached. There are two permissions required:

• ec2:DescribeInstances - Required to determine tag values of the current running instance. Can be restricted by Resource to the current instance running the application
• ec2:DescribeTags - Required to identify other instances with the same tags

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "VisualEditor0",
            "Effect": "Allow",
            "Action": [
                "ec2:DescribeInstances",
                "ec2:DescribeTags"
            ],
            "Resource": "*"
        }
    ]
}