Capistrano how to access a serverDefinition option in the code - capistrano

Question

I am defining my server setup like this:
task :test do
role(:frontend) {[server1,server2,server3, {:user=> "frontend-user", :options => {:log_location=>"HOW DO I READ THIS??"}}]}
role(:backend) {...}
role(:db) {...}
role(:mq) {...}
end
task :staging do
role(:frontend) {[server1,server2,server3, {:user=> "frontend-user", :options => {:log_location=>"HOW DO I READ THIS??"}}]}
role(:backend) {...}
role(:db) {...}
role(:mq) {...}
end
task :prod do
role(:frontend) {[server1,server2,server3, {:user=> "frontend-user", :options => {:log_location=>"HOW DO I READ THIS??"}}]}
role(:backend) {...}
role(:db) {...}
role(:mq) {...}
end
This is to embrace all the complexity of a legacy enterpricey system.
Now, from a task, I want to read the log_location.
Task example:
namespace :log do
desc "list all log files"
task :list do
run %(ls -1 #{log_location}/*/*.log)
end
end
The problem is that the variable log_location is undefined.
/.rvm/gems/ruby-2.0.0-p0/gems/capistrano-2.14.2/lib/capistrano/configuration/namespaces.rb:193:in
method_missing': undefined local variable or methodlog_location'
for
# (NameError)
How do I access that variable?
Is there a smarter/simpler way of setting this custom variable?

Answer 1

I'm sorry to say you can't read that. The blocks passed to task() aren't executed in a server context, thus the block in effect doesn't know what server it's operating on.
The classical workaround for this over the years has been to upload a config file which looks something like this:
---
hostname1:
log_file_location: "/var/log/hostname1/foo/bar"
hostname2:
log_file_location: "/var/log/hostname2/foo/bar"
(or similar) and use the machines hostname when loading the configuration.
I know this isn't a great workaround, thus in the forthcoming (see the v3 branch at Github) version of Capistrano there's a feature which looks like this:
host1 = SSHKit::Host.new 'user#example.com'
host2 = SSHKit::Host.new 'user#example.org'
host1.properties = {log_file_location: "/foo/bar"}
host2.properties.log_file_location = "/bar/baz"
on hosts do |host|
target = "/var/www/sites/"
if host.hostname =~ /org/
target += "dotorg"
else
target += "dotcom"
end
execute! :head, '-n 20', host.properties.log_file_location
execute! :git, :clone, "git#git.#{host.hostname}", target
end
(SSHKit Examples) - SSHKit is the new backend driver for Capistrano.
The v3 branch probably isn't ready for prime time yet, we're having a lot of success internally but the documentation is pretty ahem non existent. However the code is quite literally an oder of magnitude less imposing, and I think you'll find quite readable.

Answer 2

You need this: https://github.com/capistrano/capistrano/wiki/2.x-Multistage-Extension
It means that you can isolate stage specific code in separate files named after the stage. If you want to test for the stage name in the shared deploy.rb you can do that too, like this:
Put this in your deploy.rb
task :show_stage do
puts(stage)
end
Test from command line
$ cap staging show_stage
staging

Answer 3

Actually, I was able to pull out the log_location variable, but ended up with a solution that had one restriction:
I am using log location for one environment only. This is no problem in my current project, since I run the capistrano task against one role at a time.
For testing this setup, I made this task:
namespace :support do
desc "Test if the log location variable is correctly fetched from configuration"
task :test_log_location do
find_servers_for_task(current_task).each do |server|
# puts server.host
# puts server.port
# puts server.user
# puts server.options
result = "LOG LOCATION: #{server.options[:log_location]}"
#puts result
logger.info result
end
end
end
Then, for my tasks in the :log namespace, I defined the variable with set :log_location and also define the :current_role variable:
namespace :log do
def set_log_location
#set_log_location
#puts fetch(:log_location)
log_location = nil
options = nil
find_servers_for_task(current_task).each do |server|
# puts server.host
# puts server.port
# puts server.user
# puts server.options
options = server.options
log_location = server.options[:log_location]
#log_location = server.options[:current_role]
end
msg1="FATAL: you need to specify 'ROLES=frontend,backend,mq' (or one of them) from command line"
msg2="FATAL: Could not get log_location from environment/server options. I can only see these options: #{options}"
raise msg1 if ENV['ROLES'].nil?
raise msg2 if log_location.nil?
set :log_location, log_location
set :current_role, ENV['ROLES'].split(',').first
logger.info %(CURRENT_ROLE #{fetch(:current_role)})
logger.info %(THE LOG LOCATION IS: #{fetch(:log_location)})
end
end
Finally, I used a separate method to fully qualify the log path (needed for my setup -- also in the :log namespace):
def log_location
log_names = {
:frontend => "*/play.log",
:backend => "*Weblogic*/*.{log,out}"
}
loc = "#{fetch(:log_location)}/#{log_names[fetch(:current_role).to_sym]}"
logger.info "using the log location of '#{loc}'"
loc
end
Now, each task can use the specific log location like this:
desc "list all log files"
task :list do
set_log_location
run %(ls -l #{log_location})
end
I am sure this can be done more elegant, but it works for me