How do you define the same tasks differently for different roles in Capistrano?

Question

I'm using Capistrano to handle my deployment, and I've got two different roles in my setup - :web and :processing. They both have the usual :deploy tasks, but the :restart task needs to be different for the two types of server.

So my first attempt was something like this:

task :restart, :roles => :web do
    run "... web related restart stuff ..."
end

task :restart, :roles => :processing do
    run "... processing related restart stuff ..."
end

Which doesn't work, because the second :restart (for :processing role) replaces the first :restart (for the :web role), and the :web :restart never happens.

I had a quick look around to see if I could write conditional code depending on which role (or roles) a server might be in when the task is run but there's next to no documentation out there for that kind of thing. Any ideas?

Answer 1

You should use namespaces:

namespace :web do
  desc "Restart web servers"
  task :restart, :roles => :web do
    # Restart Magic Here
  end
end

namespace :process do
  desc "Restart process servers"
  task :restart, :roles => :process do
    # Restart magic here
  end
end

# Optionally:
task :restart do
  web.restart
  process.restart
end

That's what you're looking for I think!

Also, to use these on the command line, you would use

$ cap <stage>           # (if using multistage)
$ cap web:restart       # Restarts web servers
$ cap process:restart   # Restarts process servers
$ cap restart           # Restarts both process and web servers

(Source: I'm the Capistrano maintainer.)

Answer 2

You should use 'parallel' instead of 'run' in this case:

task :restart do
  parallel do |session|
    session.when "in?(:web)", "...substitute run command contents here...."
    session.when "in?(:process)", "...substitute run command contents here...."
  end
end

If you are going to use something except 'run' in different tasks you'd better stick to one of the other answers.

More info on 'parallel' command can be found here: https://github.com/capistrano/capistrano/wiki/2.x-DSL-Action-Invokation-Parallel