Alternative discovery methods

[electrical]

Not sure if it belongs here, but it would be nice if we could facilitate discovery on things like EC2. With EC2 you can put the same nodes in a security group and use the api to discover those nodes so you don't have to maintain the list of nodes. I know Elasticsearch uses this for EC2, im sure we can implement same kind of solution

[electrical]

Possible settings.

discovery.method: 'static', 'ec2'

# Static host list
discovery.static.seed.1: host1
discovery.static.seed.2: host2

# EC2 discovery
discovery.ec2.access_key: 
discovery.ec2.secret_key: 
discovery.ec2.region: 
discovery.ec2.protocol: 'https', 'http'
discovery.ec2.groups:
discovery.ec2.host_type: 'private_ip', 'public_ip', 'private_dns', 'public_dns'
discovery.ec2.availability_zones:

[electrical]

We could create a separate module of it so that people don't need the extra libraries ( amazon sdk ) by default.