Referencing the current server in Capistrano task

Question

How would I reference the current server in a Capistrano task? I want to curl a local file to clear the APC cache but the server does not listen on localhost so I need the server's IP address.

For instance,

role :web, "1.1.1.1", "2.2.2.2", "3.3.3.3"

task :clear_apc, :role => :web do
    run "curl http://#{WHAT_DO_I_PUT_HERE}/deploy/clearAPC.php"
end

What variable would I use so that when the task is run on 1.1.1.1 it curls http://1.1.1.1/deploy/clearAPC.php but when run on 2.2.2.2 it calls curls http://2.2.2.2/deploy/clearAPC.php

score 29 · Answer 1 · answered Nov 20 '12 at 11:53

29

In Capistrano, tasks don't get executed once for each server, run executes your command on each server. Here is what you should do instead:

task :clear_apc, :role => :web do
    find_servers_for_task(current_task).each do |current_server|

        run "curl http://#{current_server.host}/deploy/clearAPC.php", :hosts => current_server.host

    end
end

The accepted answer will work, but this one lets you access the servers as variables/methods

answered Nov 20 '12 at 11:53

user1158559

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`find_servers_for_task` works exactly as described. Thank you! – piersadrian Apr 02 '13 at 16:43
1

This works better than the accepted answer, especially if you decide to use capture() instead of run(). – Joel E Salas Sep 04 '13 at 01:41

score 11 · Accepted Answer · answered Jun 15 '12 at 16:13

11

There's the magical $CAPISTRANO:HOST$

run "curl http://$CAPISTRANO:HOST$/deploy/clearAPC.php"

should do exactly what you want.

note: don't use it as a variable via string interpolation, capistrano will just replace the $CAPISTRANO:HOST$ in the string itself.

That's a very weird and (afaik) undocumented feature :-)

answered Jun 15 '12 at 16:13

Pascal

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This looks really hacky. Why didn't the Capistrano guys make it a method? – user1158559 Nov 16 '12 at 12:22
maybe @leehambley knows the answer ;) I'll point him to this question – Pascal Nov 16 '12 at 16:08
user1158559 has a much better answer, though it's not the accepted one. – Nate Mar 26 '13 at 15:02
@Nate the question was how to access the hostname and that's the fastest way. Could you please elaborate why you prefere the way longer method below over the my solution, considering the original question? – Pascal Mar 26 '13 at 15:46
Because good lord, is $CAPISTRANO:HOST$ ugly as sin. It looks like magic. Making the loop explicit seems like a good idea to me. It is worth noting: it is documented here: https://github.com/capistrano/capistrano/wiki/2.x-DSL-Action-Invocation-Run – Nate Mar 26 '13 at 17:19
@Nate I never said it's beautiful, but I answered the original question. I do however respect your opinion, I just didn't see the reason for the downvote because the answer is 100% legit – Pascal Mar 27 '13 at 10:15
Sigh, you're right; it really didn't deserve a downvote. However, SO doesn't seem to let me undownvote it :/ – Nate Mar 27 '13 at 15:44
Technically the OP asked what should be put inside his ruby string interpolation and what variable he should use! :) – user1158559 Sep 06 '13 at 01:07

score 3 · Answer 3 · answered Aug 28 '13 at 13:45

3

current_host = capture("echo $CAPISTRANO:HOST$").strip

answered Aug 28 '13 at 13:45

Florian Eck

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I prefer this. For `system` commands, $CAPISTRANO:HOST$ doesn't work while using this works great. – Bibek Shrestha Sep 16 '13 at 11:50

score 1 · Answer 4 · answered Jan 07 '20 at 15:42

Capistrano 3 - server is available as an object, with set of properties, in the roles block :

on roles(:app) do |server|

So for example to pass the hostname property to docker compose

  on roles(:app)  do |server|
    execute "docker-compose --build-arg SOME_HOST_NEEDED=#{server.hostname} ......
  end

score 0 · Answer 5 · answered Dec 07 '12 at 23:51

I wanted to know the current server I was deploying to, so that I could send a message to campfire. This is what I was able to figure out, though I'm sure there is a better way

 actions = current_task.namespace.parent.logger.instance_variable_get('@options')[:actions]
 message = "I am deploying #{fetch(:latest_release).split('/').last} using cap #{actions.join(' ')}"

so when I deploy it posts this to campfire I am deploying 20121206154442 using cap QA2 campfire:notify deploy deploy:flex_master

score 0 · Answer 6 · answered Jan 30 '14 at 21:32

0

capistrano (2.13.5) required

puts current_task.namespace.logger.instance_variable_get('@base_logger').instance_variable_get('@options')[:actions].join(' ')

figured this out by

puts current_task.namespace.logger.inspect

answered Jan 30 '14 at 21:32

user3255084

1

Referencing the current server in Capistrano task

6 Answers6