CPD-183: Added pre-check to plugin (#270)

Change: minor
Purpose: feature

docs/plugins/rotate_asg_instances.md

@@ -9,12 +9,9 @@ After all outdated instances are shutdown successfully, it terminates them and r
 It allows gracefully shutting down each instance instead of terminating them and killing all the running processes.
 
 ## Configuration
-The plugin uses the ssh username specified in the `MOONSHOT_SSH_USER` or the `LOGNAME` environment variable for logging into the ASG instances to shutdown. The value should be the username with which you have the access to the instances. For example:
-```ruby
-export MOONSHOT_SSH_USER=abhishek.rana
-```
+The plugin uses config.ssh_config.ssh_user value for logging into the ASG instances to shutdown. The value should be the username with which you have the access to the instances.
 
-The plugin needs no additional configuration parameters:
+The plugin accepts additional configuration from config.ssh_config.ssh_options for ssh.
 
 ## Example
 ```ruby

lib/moonshot/ssh_command_builder.rb

@@ -12,6 +12,7 @@ def initialize(ssh_config, instance_id)
 
     def build(command = nil)
       cmd = ['ssh', '-t']
+      cmd << @config.ssh_options if @config.ssh_options
       cmd << "-i #{@config.ssh_identity_file}" if @config.ssh_identity_file
       cmd << "-l #{@config.ssh_user}" if @config.ssh_user
       cmd << instance_ip

lib/moonshot/ssh_config.rb

@@ -2,10 +2,12 @@ module Moonshot
   class SSHConfig
     attr_accessor :ssh_identity_file
     attr_accessor :ssh_user
+    attr_accessor :ssh_options
 
     def initialize
       @ssh_identity_file = ENV['MOONSHOT_SSH_KEY_FILE']
       @ssh_user = ENV['MOONSHOT_SSH_USER']
+      @ssh_options = ENV['MOONSHOT_SSH_OPTIONS']
     end
   end
 end

lib/moonshot/ssh_fork_executor.rb

@@ -3,18 +3,18 @@
 module Moonshot
   # Run an SSH command via fork/exec.
   class SSHForkExecutor
-    Result = Struct.new(:output, :exitstatus)
+    Result = Struct.new(:output, :error, :exitstatus)
 
     def run(cmd)
-      output = StringIO.new
-
+      output = error = StringIO.new
       exit_status = nil
-      Open3.popen3(cmd) do |_, stdout, _, wt|
+      Open3.popen3(cmd) do |_, stdout, stderr, wt|
+        error << stderr.read until stderr.eof?
         output << stdout.read until stdout.eof?
         exit_status = wt.value.exitstatus
       end
 
-      Result.new(output.string.chomp, exit_status)
+      Result.new(output.string.chomp, error.string.chomp, exit_status)
     end
   end
 end

lib/plugins/rotate_asg_instances.rb

@@ -1,16 +1,39 @@
 # frozen_string_literal: true
 
 require 'aws-sdk'
-require_relative 'rotate_asg_instances/asg'
 
 module Moonshot
   module Plugins
     # Rotate ASG instances after update.
     class RotateAsgInstances
+      include DoctorHelper
+
+      def doctor(resources)
+        @resources = resources
+        run_all_checks
+      end
+
+      def pre_update(resources)
+        @resources = resources
+        asg.verify_ssh
+      end
+
       def post_update(resources)
-        asg = ASG.new(resources)
-        asg.rotate_asg_instances
-        asg.teardown_outdated_instances
+        @resources = resources
+        asg.perform_rotation
+      end
+
+      private
+
+      def asg
+        Moonshot::RotateAsgInstances::ASG.new(@resources)
+      end
+
+      def doctor_check_ssh
+        asg.verify_ssh
+        success('Successfully opened SSH connection to an instance.')
+      rescue Moonshot::RotateAsgInstances::SSHValidationError
+        critical('SSH connection test failed, check your SSH settings')
       end
     end
   end