Add hostname as prefix for SSH output lines

src/util/prefixed_io.cr

@@ -0,0 +1,14 @@
+class PrefixedIO < IO
+  def initialize(@prefix : String, @io : IO); end
+
+  def read(slice : Bytes)
+    raise NotImplementedError.new "#read"
+  end
+
+  def write(slice : Bytes) : Nil
+    content = String.new(slice)
+    content.lines.each do |line|
+      @io << @prefix << "#{line}\n"
+    end
+  end
+end

src/util/ssh.cr

@@ -3,6 +3,7 @@ require "io"
 require "../util"
 require "retriable"
 require "tasker"
+require "./prefixed_io"
 
 class Util::SSH
   getter private_ssh_key_path : String
@@ -42,7 +43,7 @@ class Util::SSH
 
     result = IO::Memory.new
     all_output = if print_output
-      IO::MultiWriter.new(STDOUT, result)
+      IO::MultiWriter.new(PrefixedIO.new("[#{server.name}] ", STDOUT), result)
     else
       IO::MultiWriter.new(result)
     end