from invocation.rb
# The +options+ hash may include any of the following keys:
# * :once - if true, only the first matching server will be
selected. The default
# is false (all matching servers will be selected).
so you can do:
task :uptime_once, :roles => [:app] do
run "uptime", :once => true
run "ls", :once => true
end
but I wanted all of the commands of a task to be run on only one
instance.
task :uptime_task_once, :roles => :app, :once => true do
run "uptime"
run "ls"
end
The use is that I want to run rake tasks and the migrates on the :app
servers so I don't have to deploy code onto the mysql roles. I also
felt having it specified on the task made more sense that specifying
at the command level.
So I require the following from my cap scripts to add supporting
the :once option at the task level.
module Capistrano
class Configuration
module Servers
# Identifies all servers that the given task should be executed
on.
# The options hash accepts the same arguments as #find_servers,
and any
# preexisting options there will take precedence over the
options in
# the task.
def find_servers_for_task(task, options={})
find_servers(task.options.merge(options))
end
# Attempts to find all defined servers that match the given
criteria.
# The options hash may include a :hosts option (which should
specify
# an array of host names or ServerDefinition instances),
a :roles
# option (specifying an array of roles), an :only option
(specifying
# a hash of key/value pairs that any matching server must
match), and
# an :exception option (like :only, but the inverse).
#
# Additionally, if the HOSTS environment variable is set, it
will take
# precedence over any other options. Similarly, the ROLES
environment
# variable will take precedence over other options. If both
HOSTS and
# ROLES are given, HOSTS wins.
#
# Yet additionally, if the HOSTFILTER environment variable is
set, it
# will limit the result to hosts found in that (comma-separated)
list.
#
# Usage:
#
# # return all known servers
# servers = find_servers
#
# # find all servers in the app role that are not exempted
from
# # deployment
# servers = find_servers :roles => :app,
# :except => { :no_release => true }
#
# # returns the given hosts, translated to ServerDefinition
objects
# servers = find_servers :hosts => "[email protected]"
def find_servers(options={})
hosts = server_list_from(ENV['HOSTS'] || options[:hosts])
if hosts.any?
filter_server_list(hosts.uniq)
else
roles = role_list_from(ENV['ROLES'] || options[:roles] ||
self.roles.keys)
only = options[:only] || {}
except = options[:except] || {}
servers = roles.inject([]) { |list, role| list.concat
(self.roles[role]) }
servers = servers.select { |server| only.all? { |key,value|
server.options[key] == value } }
servers = servers.reject { |server| except.any? { |
key,value| server.options[key] == value } }
#allows you to add the option :once to a task ie:
task :my_task, :roles => :app, :once => true do ...
servers = [servers.first] if options[:once]
logger.trace "servers: #{servers.map { |s|
s.host }.inspect}"
filter_server_list(servers.uniq)
end
end
end
end
end
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