There's not really a special syntax for delayed evaluation of roles,
but you can programmatically set roles in tasks:
task :set_roles do
servers = something_that_returns_an_array_of_server_names
role :app, *servers
end
Note that because a task is run for all matching servers in parallel,
the question "can I query what server the task is being run on right
now" doesn't really make sense. However, if you need to substitute
the server name in a command, you can do (e.g.):
run "echo $CAPISTRANO:HOST$"
That would echo the name of the current host to the screen. That only
works inside of the command that you pass to run or sudo, though,
because run/sudo substitute that placeholder text with the server
name immediately before sending the command to the corresponding server.
If you want to run a command on only a single host at a time, you can
pass the :hosts key to run/sudo:
run "this is on foo.bar.com", :hosts => "foo.bar.com"
run "this is on baz.bang.com", :hosts => "baz.bang.com"
Note that you lose the parallelization this way, since the first run
must finish before the second one can start. That may not matter to you.
- Jamis
On Jun 13, 2007, at 3:59 PM, hemant wrote:
>
> Hi,
>
> Basically for some of my deployment machines, I have entirely
> different mongrel_cluster.conf and for rest of them its the same.
>
> So basically when cap is using mongrel_cluster.conf to restart my
> mongrels on those machines, I want cap to pick different cluster
> config file.
>
> Plain vanilla setup has:
>
> set :mongrel_conf, "#{current_path}/config/mongrel_cluster.yml"
>
> So on every machine, it would look for mongrel_cluster.yml file. Now,
> for some machines I want cap to use
> #{current_path}/config/mongrel_cluster_www4.yml.
>
> I saw delayed evaluation of variables, but wasn't sure, how can i turn
> that facility to my evil purposes.
>
> Also, if somehow within a task,
>
> task :restart, :roles => :app do
> # app was an array, and If I can get for which machine currently
> this task is executed
> # then I should be able to pull this trick.
> end
>
>
> --
> gnufied
> -----------
> There was only one Road; that it was like a great river: its springs
> were at every doorstep, and every path was its tributary.
> http://people.inxsasia.com/hemant
>
> >
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