From: tamouse mailing lists <tamouse.lists@...>
Date: 2013-05-13T06:10:37+09:00
Subject: Re: Help convert sh -> rb

On Fri, May 10, 2013 at 5:17 PM, Micah H. <lists@ruby-forum.com> wrote:
>> What have you written so far?
>
> Haven't worked it much yet, I've only got...I need to figure out how to
> save the output so I can store my variables.
>
> #!/usr/bin/env ruby
> rds_describe = `rds-describe-db-instances`
>
>
> puts "
> {
>     \"checks\": {
>         \"mysql_disk_usage_$I\": {
>             \"handlers\": [\"default\",\"mailer_alerts\"],
>             \"command\": \"/etc/sensu/plugins/mysql-disk.rb -h$I u -p
> -s$S\",
>             \"interval\": 300,
>             \"occurrences\": 1,
>             \"subscribers\": [
>                 \"urls\"
>             ]
>         },
> "

Perhaps setting it up as a hash of hashes, or a class of classes might
be more useful, and then using #to_json to emit the json.

A simple hash of the above would look something like this:

check_hash =
  { "checks" =>
      "mysql_disk_usage+#{i}" => {
        "handlers" =>
          ["default", "mailer_alerts"],
        "command" => "/etc/sensu/plugins/mysql-desk.rb -h#{i} u -p -s {#s}",
        "interval" => 300,
        "occurances" => 1,
        "subscribers" => ["urls"]
      }
   }

then you can get the json by:

puts check_hash.to_json

which saves all the quote escaping and what-not.

Note the #{i} and #{s} in the above -- these correspond to the I and S
variables in the bash script, but you'd need to get at them
differently.

Starting off, you read in the output from the command by:

rds_describe = `rds-describe-db-instances`

you can walk through it with something like:

rds_describe.split("\r?\n").each do |line|

  s, i = line.split()

  puts { "checks" =>
          "mysql_disk_usage+#{i}" => {
            "handlers" => ["default", "mailer_alerts"],
            "command" => "/etc/sensu/plugins/mysql-desk.rb -h#{i} u -p -s {#s}",
            "interval" => 300,
            "occurances" => 1,
            "subscribers" => ["urls"]
          }
       }.to_json

end

(Note you need a require 'json' at the beginning of the script.)

This will basically replicate your bash script in ruby form.