there is an Ec2-rails group that is about to move in to their
territory. They are ripe for a code swap.
Paul
On Sep 30, 10:57 am, Joe <[EMAIL PROTECTED]> wrote:
> Hi all,
>
> I've been working on a plugin to manage deployments of clusters on EC2
> through Capistrano. I'm looking to see if anyone is interested in
> collaborating on it, or using it in alpha form to give me some
> feedback. I'm not going to release it yet since it needs more
> development and testing, but I would like to get some suggestions on
> features to add.
>
> The tool is meant to manage the setup and confiiguration of machines
> prior to running a normal cap:deploy of a specific application. It is
> not meant to replace that.
>
> Here's an example of a cluster recipe (this is made up, so there may
> be some logical errors in the setup, but it should illiustrate the
> idea):
>
> -----
>
> cluster = elasticize.creater_cluster("mykey") do
> on_create do |cluster|
> app_group = create_group(cluster, :app) do
> authorize_ingress :proto => :tcp, :ports => 22
> authorize_ingress :proto => [ :tcp, :udp ], :ports => 5036
> end
> webserver_group = create_group(cluster, :webserver_group) do
> authorize_ingress :proto => :tcp, :ports => [ 22, 80 ]
> end
>
> app_group.authorize_ingress :from => :webserver_group
> webserver_group.authorize_ingress :from => :app_group
> end
> end
>
> app = elasticize.create_image :app, 'ami-12345678',
> cluster, :app_group
> web = elasticize.create_image :web, 'ami-87654321',
> cluster, :webserver_group do
> on_create do
> # Get security updates
> run "aptitude update -y"
> run "aptitude upgrade -y"
> end
> end
>
> elasticize.create_role :postfix, web do
> on_create do |process|
> modify "/etc/postfix/main.cf" do |r|
> r.sub(/(^myhostname[^=]*=.*$)/, "myhostname =
> #{process.instance.dns}")
> end
> end
>
> on_stop { run "/etc/init.d/postfix stop" }
> on_start do |process|
> run "/etc/init.d/postfix start"
> process.notify! :app, :port => 1234
> end
> end
>
> elasticize.create_role :app, rails do
> needs :db, :primary => true
> needs :postfix
>
> on_receive do |process, source, event, *rest|
> if event == :on_start
> case source.role.name.to_sym
> when :db
> ip = process.instance.private_dns
> port = *rest
> when :postfix
> # TODO: modify the rails configuration to point to the postfix
> server
> ip = process.instance.private_dns
> port = *rest
> end
> end
> end
> end
>
> # Create an elastic role for the web server, bound to the 'rails' AMI
> elasticize.create_role :web, rails do
> needs :app
>
> on_receive do |process, source, event, *rest|
> if event == :on_start
> case source.role.name.to_sym
> when :app
> end
> end
> end
>
> on_create do
> # Install needed gems
> install_gem "daemons"
> install_gem "gem_plugin"
> install_gem "mongrel_cluster"
> install_gem "mongrel", :version => '1.0.1'
> end
> end
>
> -----
>
> You can then create the cluster with a cap cluster:create. This will
> create the keys, security groups, permissions and instances. When a
> particular instance is created, its corresponding image's 'on_start'
> callback is called. Additionally, the create task will bind all
> 'elasitc' roles to a particular machine and create the appropriate
> capistrano role internally. When the binding occurs, the corresponding
> on_start callback are called for the process' corresponding role.
> There are additional callbacks when instances are terminated or leave
> the cluster.
>
> The 'needs' method indicates that a particular elastic role is
> dependent upon another, and that its' processes will accept
> notifications (in the on_receive handler) of specific events within
> the cluster from prerequisite processes (where a process represents a
> binding of a role to an EC2 instance, since a role can have multiple
> processes). The notifications are specified via the notify! method in
> a process' on_start callback, and allows that process to deliver
> dynamic configuration data to its dependent roles' processes.
>
> The 'provides' method specifies the number of processes which will
> exist for a given role. Also, 'create_role' can specify capistrano
> subroles (limited to a hash of keys to boolean values for now) like
> this:
>
> primary = elasticize.create_role :db, some_image, :primary => true do
> # Default is one if unspecified
> provides :exactly => 1
> end
>
> secondary = elasticize.create_role, :db, some_image do
> provides :min => 2, :max => 4
> end
>
> A planned feature will allow you to add and remove processes
> dynamically, bounded by the min / max number specified in the recipe.
>
> cap cluster:add ROLE=db
>
> This is not meant to be a thorough write up, just a taste if what is
> available.
>
> If you think you may be able to help, or just have some ideas for what
> you'd like to see, please get in touch. In particular, API feedback or
> help writing tests would be greatly appreciated.
>
> Joe
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