Cap-EC2 is used to generate Capistrano namespaces and tasks from Amazon EC2 instance tags, dynamically building the list of servers to be deployed to.
Cap-EC2 is only compatible with Capistrano 3.x or later; if you want the Capistrano 2.x version,
use Capify-EC2. Note that the configuration file (config/ec2.yml)
is not compatible between versions either.
This documentation assumes familiarity with Capistrano 3.x.
A number of features that are in Capify-EC2 are not yet available in Cap-EC2, due to the architectural changes in Capistrano 3.x. The following features are missing (this is not an exhaustive list!):
- rolling deploy (this should be implemented via SSHKit)
- ELB registration/de-registration (not widely used)
- Variables set by EC2 tags
- Connecting to instances via SSH using a convenience task
Pull requests for these would be welcomed, as would sending feedback via the Issues on this project about features you would like.
gem install cap-ec2
or add the gem to your project's Gemfile.
You also need to add the gem to your Capfile:
require "cap-ec2/capistrano"Configurable options, shown here with defaults:
set :ec2_config, 'config/ec2.yml'
set :ec2_project_tag, 'Project'
set :ec2_roles_tag, 'Roles'
set :ec2_stages_tag, 'Stages'
set :ec2_access_key_id, nil
set :ec2_secret_access_key, nil
set :ec2_region, %w{}
set :ec2_contact_point, nil
set :ec2_filter_by_status_ok?, nilcap-ec2 supports multiple methods of configuration. The order of inheritance is:
YAML File > User Capistrano Config > Default Capistrano Config > ENV variables.
:ec2_region is an array of AWS regions, if not present all regions will be checked for matching instances - this the default behavior and can be slow, if speed is an issue consider setting your required regions.
If:ec2_access_key_id or :ec2_secret_access_key are not set in any configuration the environment variables
AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY and AWS_REGION will be checked.
If running on EC2 the IAM instance profile credentials will be used if credentials are not set by any other method.
-
project_tag
Cap-EC2 will look for a tag with this name when searching for instances that belong to this project. Cap-EC2 will look for a value which matches the :application setting in your deploy.rb. The tag name defaults to "Project" and must be set on your instances.
-
stages_tag
Cap-EC2 will look for a tag with this name to determine which instances belong to a given stage. The tag name defaults to "Stages".
-
roles_tag
Cap-EC2 will look for a tag with this name to determine which instances belong to a given role. The tag name defaults to "Roles".
-
filter_by_status_ok?
If this is set to
true, then Cap-EC2 will not return instances which do not have both EC2 status checks asOK. By default this is set tonil, so Cap-EC2 can return you instances which don't haveOKstatus checks. Be warned that just-launched instances take a while to start returningOK.
If you'd prefer do your configuration via a YAML file config/ec2.yml can be used, (or an alternative name/location set via set :ec2_config):
If so YAML file will look like this:
access_key_id: "YOUR ACCESS KEY"
secret_access_key: "YOUR SECRET KEY"
regions:
- 'eu-west-1'
project_tag: "Project"
roles_tag: "Roles"
stages_tag: "Stages"Your config/ec2.yml file can contain (access_key_id, secret_access_key, regions) - if a value is omitted then the order of inheritance is followed.
Imagine you have four servers on EC2 named and tagged as follows:
| 'Name' Tag | 'Roles' Tag | 'Stages' Tag |
| server-1 | web | production |
| server-2 | web,app | production |
| server-3 | app,db | production |
| server-4 | web,db,app | staging |
Imagine also that we've called our app "testapp", as defined in config/deploy.rb like so:
set :application, "testapp"
To define a role, edit config/deploy/[stage].rb and add the following:
ec2_role :web
Let's say we edited config/deploy/production.rb. Adding this configuration to the file would assign
the role :web to any instance that has the following properties:
- has a tag called "Roles" that contains the string "web"
- has a tag called "Project" that contains the string "testapp"
- has a tag called "Stages" that contains the current stage we're executing (in this case, "production")
Looking at the above table, we can see we would match server-1 and server-2. (You can have multiple
roles in tag separated by commas.)
Now we can define the other roles:
ec2_role :app
ec2_role :db
In the "production" stage, the :app role would apply to server-2 and server-3, and the :db
role would apply to server-3.
In the "staging" stage, all roles would apply only to server-4.
If you require your servers to have multiple projects deployed to them, you can simply specify
all the project names you want to the server to be part of in the 'Projects' tag, separated
by commas. For example, you could place a server in the testapp and myapp projects by
setting the 'Projects' tag to testapp,myapp.
If your use-case requires servers to be in multiple stages, simply specify all the stages you want
the server to be in 'Stages' tag, separated by commas. For example, you could place a server in
the production and staging stages by setting the 'Stages' tag to production,staging.
You can pass options when defining your roles. The options are exactly the same as the options that
the Capistrano native role definition takes, since they are passed straight through to Capistrano.
For example:
ec2_role :app,
user: 'user_name',
ssh_options: {
user: 'user_name', # overrides user setting above
keys: %w(/home/user_name/.ssh/id_rsa),
forward_agent: false,
auth_methods: %w(publickey password)
password: 'please use keys'
}
See the example config files Capistrano builds for you in config/deploy for more details.
Note that at the moment there's no way to pass variables in from EC2 tags - but it would be trivial to add.
You can now define your tasks for these roles in exactly the same way as you would if you weren't using this gem.
By default, Cap-EC2 will attempt to communicate with the EC2 instance using the following instance interfaces in order:
- Public DNS (
:public_dns) - Public IP (
:public_ip) - Private IP (
:private_ip)
This can be configured using the Capistrano variable :ec2_contact_point, and supplying one
of the above symbols. For example:
set :ec2_contact_point, :private_ipThis would cause Cap-EC2 to try communicating with the instance on its private IP address. If you leave this variable unset, the behaviour is as in previous Cap-EC2 instances (falling through the lookup list as specified above).
Cap-EC2 adds a few utility tasks to Capistrano for displaying information about the instances that you will be deploying to. Note that unlike Capistrano 2.x, all tasks require a stage.
This command will show you information all the instances your configuration matches for a given stage.
cap [stage] ec2:status
Example:
$ cap production ec2:status
Num Name ID Type DNS Zone Roles Stage
00: server-1-20131030-1144-0 i-abcdefgh m1.small 192.168.202.248 us-west-2c banana,apple production
01: server-2-20131118-1839-0 i-hgfedcba m1.small 192.168.200.60 us-west-2a banana production
This command will show you the server names of the instances matching the given stage:
cap [stage] ec2:server_names
Example:
$ cap production ec2:server_names
server-1-20131030-1144-0
server-2-20131118-1839-0
This command will show the instance IDs of the instances matching the given stage:
cap [stage] ec2:instance_ids
Example:
$ cap production ec2:instance_ids
i-abcdefgh
i-hgfedcba
Thanks to Rylon for maintaining Capify-EC2 and reviewing my thought processes for this project.
- Fork it
- Create your feature branch (
git checkout -b my-new-feature) - Commit your changes (
git commit -am 'Add some feature') - Push to the branch (
git push origin my-new-feature) - Create new Pull Request