Capistrano 3.x capture output line by line

Question

In Capistrano 2.x you could capture the output line by line using

run "ls -la" do |channel, stream, data|
    puts data
end

This does not work in Capistrano 3.x, and the capture and execute commands do not seem to provide the same functionality.

Is there a way to replicate the 2.x behaviour in 3.x?

Answer 1

output = capture('cat ~/file.cnf')
output.each_line do |line|
    puts line
end

Thats how I read lines using capture. If you want to capture something specific on a line you can use

if line.include? 'user'

Answer 2

I could not figure out how to get streaming output in cap 4 either. For me in Cap 3.4.0 with sshkit 1.11.1, execute was not doing it.

But looking at the sshkit docs, here's one way to hack it, which kind of works:

class StreamOutputInteractionHandler
  def on_data(_command, stream_name, data, channel)
    $stderr.print data
  end
end

# ...

execute :whatever, interaction_handler: StreamOutputInteractionHandler.new

It might do weird things, especially if you are executing on multiple hosts, it will of course interleave the output. You can use capistrano log similar to the way the built in MappingInteractionHandler does, but I wanted to print directly to console so I could get partial output before newlines (a progress bar from a rake task).

Discussion with sshkit maintainer here. https://github.com/capistrano/sshkit/issues/395#issuecomment-288489866