Module: Capistrano::Configuration::LoadBalancers

Included in:
Capistrano::Configuration
Defined in:
lib/cap-elb.rb

Instance Method Summary collapse

Instance Method Details

#loadbalancer(named_load_balancer, *args) ⇒ Object

This will give you the list of hosts behind the load balancer that meet the criteria. % cap ec2:list

Raises:

  • (Exception) 


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# File 'lib/cap-elb.rb', line 90

def loadbalancer (named_load_balancer, *args)

 require_arglist = args[1][:require] rescue {}
 exclude_arglist = args[1][:exclude] rescue {}
 named_region = fetch(:aws_params)[:region] rescue 'us-east-1'

 # can't have a EC2_URL env var if region has been provided
 # otherwise the RightScale gem will overresolve the url and region and form a bad endpoint
 # in the RightAWS::Ec2.new class
 # this undefine only lasts the extent of the cap task, doesn't affect the parent process.
 ENV['EC2_URL'] = nil if !named_region.nil?

 # list of all the instances assoc'ed with this account
 @ec2_api ||= RightAws::Ec2.new(fetch(:aws_access_key_id), fetch(:aws_secret_access_key), fetch(:aws_params, {}))

 # fetch a raw list all the load balancers
 @elb_api ||= RightAws::ElbInterface.new(fetch(:aws_access_key_id), fetch(:aws_secret_access_key), :region => named_region)
 
 # only get the named load balancer
 named_elb = @elb_api.describe_load_balancers.delete_if{ |instance| instance[:load_balancer_name] != named_load_balancer.to_s }

 # must exit if no load balancer on record for this account by given name in cap config file
 raise Exception, "No load balancer found named: #{named_load_balancer.to_s} for aws account with this access key: #{fetch(:aws_access_key_id)} in this region: #{named_region}" if named_elb.nil?
 # probe for the load balancer ec2 instance set, if this raises Exception, load balancer can't be found
 named_elb[0] rescue raise Exception, "No load balancer found named: #{named_load_balancer.to_s} for aws account with this access key: #{fetch(:aws_access_key_id)} in this region: #{named_region}" 
 raise Exception, "No instances within this load balancer: #{named_load_balancer.to_s} for aws account with this access key: #{fetch(:aws_access_key_id)} in this region: #{named_region}" if  named_elb[0][:instances].count == 0

 elb_ec2_instances = named_elb[0][:instances] rescue {}

 # get the full instance list for account, this is necessary to subsquently fish out the :dns_name for the instances that survive our reduction steps
  = @ec2_api.describe_instances

 # reduce to only the instances in the named ELB
 .delete_if { |i| ! elb_ec2_instances.include?(i[:aws_instance_id]) }

 # reduce against 'require' args, if an instance doesnt have the args in require_arglist, remove
 .delete_if { |i| ! all_args_within_instance(i, require_arglist) }  unless require_arglist.nil? or require_arglist.empty?

 # reduce against 'exclude_arglist', if an instance has any of the args in exclude_arglist, remove
 .delete_if { |i|   any_args_within_instance(i, exclude_arglist) }  unless exclude_arglist.nil? or exclude_arglist.empty?

 # finally load the derived instances into the serverlist used by capistrano tasks
 .each do |instance|
  hostname = instance[:dns_name] 
  hostname = instance[:ip_address] if hostname.empty?   # if host in a VPC, there will be no DNS name, use ip_address instead
  server(hostname, *args)
 end
end