I am managing all my instances with the AWS Management Console (the GUI web console) but now I want to use Auto Scale and it seems that this can not be done with that console. Yes, there is CloudWatch but I can only create alarms (e-mail notifications), it seems that CouldWatch needs you to add the auto scale policy in some other place (by command line console?). I would like to use some easy GUI interface. Ylastic and Scalr seems to be a good option. Which one do you think is better?
Regarding Scalr, is there any difference between the open source software Scalr and the service Scalr.net? I mean, is the GUI interface the same? I like the idea of the Scalr because I do not need to give my Secret Access Key to a third party (like in Ylastic or in Scalr.net)
One question about the Scalr software, it has to be installed in the instances or it must be installed in another machine? Do I need to setup again all my security permissions, AMIs, snapshots, etc. or I can use AWS Management Console for everything and Scalr just to auto scale.
Regarding Scalr's open-source vs hosted version, GUI is the same - I am just not 100% sure if the open source version is 100% up to date. We are using the hosted version.
Scalr itself (if you chose to host it yourself) needs to run separately in order to manage your EC2 instances. This will give you a nice overview:
http://scottmartin.net/2009/07/11/creating-a-virtual-datacenter-with-scalr-and-amazon-web-services/
In theory you can migrate your current instances to scalr but I am sure devil is in the details. Some careful planning would be required in order to complete the migration:
http://wiki.scalr.net/Tutorials/Migrating_instances_to_Scalr
If you use standard components, you might prefer to use Scalr's ready server templates (Roles in scalr terminology) those as starting points and modify as needed.
In general I can highly recommend Scalr as a value for money alternative to Rightscale. You will surely appreciate the automation and configuration capabilities vs managing things manually via the aws interface.
You should also take a look at http://rightscale.com , autoscaling triggers based on many metrics. A lot of automation and ready to use load balancers , app servers and db servers.