Make kamal use ssh keys from config when performing commands

lib/kamal/commands/base.rb

@@ -17,6 +17,10 @@ def run_over_ssh(*command, host:)
         elsif config.ssh.proxy && config.ssh.proxy.is_a?(Net::SSH::Proxy::Command)
           cmd << " -o ProxyCommand='#{config.ssh.proxy.command_line_template}'"
         end
+        config.ssh.keys.each do |key|
+          cmd << " -i #{key}"
+        end
+        cmd << " -o IdentitiesOnly=yes" if config.ssh.keys_only
         cmd << " -t #{config.ssh.user}@#{host} -p #{config.ssh.port} '#{command.join(" ").gsub("'", "'\\\\''")}'"
       end
     end

test/commands/app_test.rb

@@ -291,6 +291,16 @@ class CommandsAppTest < ActiveSupport::TestCase
     assert_equal "ssh -J root@2.2.2.2 -t app@1.1.1.1 -p 22 'ls'", new_command.run_over_ssh("ls", host: "1.1.1.1")
   end
 
+  test "run over ssh with keys config" do
+    @config[:ssh] = { "keys" => ["path_to_key.pem"] }
+    assert_equal "ssh -i path_to_key.pem -t root@1.1.1.1 -p 22 'ls'", new_command.run_over_ssh("ls", host: "1.1.1.1")
+  end
+
+  test "run over ssh with keys config with keys_only" do
+    @config[:ssh] = { "keys" => ["path_to_key.pem"], "keys_only" => true }
+    assert_equal "ssh -i path_to_key.pem -o IdentitiesOnly=yes -t root@1.1.1.1 -p 22 'ls'", new_command.run_over_ssh("ls", host: "1.1.1.1")
+  end
+
   test "run over ssh with proxy_command" do
     @config[:ssh] = { "proxy_command" => "ssh -W %h:%p user@proxy-server" }
     assert_equal "ssh -o ProxyCommand='ssh -W %h:%p user@proxy-server' -t root@1.1.1.1 -p 22 'ls'", new_command.run_over_ssh("ls", host: "1.1.1.1")