Destroy script for provisioning

Question

Script intended to remove Vault & Consul setup before run re-provision them on server.

This is my first Ruby script, so will be perfect to see my mistakes here.

#!/usr/bin/env ruby

require 'net/ssh'

$me = File.basename(__FILE__)

print "\n[#{$me}] Vault & Consul DESTROY started on the #{$HOST}.\n"

if not ARGV.empty? then
    $HOST = ARGV[0]
    puts "\n[#{$me}] Working on the #{$HOST}"
else
    puts "[#{$me}] ERROR: host to destroy must be in first argument. Exit."
    exit 1
end

$USER = 'knife';
$RSA_KEY = 'ssh/id_rsa';

$HOMES = {
        "vault" => "/opt/vault/",
        "consul" => "/opt/consul/"
        }

if File.exist?($RSA_KEY) then
    File.chmod(0600, $RSA_KEY)
else
    puts "[#{$me}] ERROR: no RSA file #{$RSA_KEY} found. Exit."
    exit 1
end


def service_check(service)
    Net::SSH.start($HOST, $USER, :keys => $RSA_KEY) do |ssh|
        process_status = ssh.exec!("sudo ps aux | grep #{service} | grep -v grep | wc -l")
        return process_status
    end
end


def service_delete(service_path)
        Net::SSH.start($HOST, $USER, :keys => $RSA_KEY) do |ssh|
        res = ssh.exec!("if test -d #{service_path}; then 
                            ls -l #{service_path}
                        else
                            echo \"ERROR: no #{service_path} directory found. Exit.\"
                            exit 1
                        fi; echo $?")
        puts res
    end
end


def service_stop(service)
    Net::SSH.start($HOST, $USER, :keys => $RSA_KEY) do |ssh|
        if ssh.exec!("sudo service #{service} stop; echo $?") then
            puts "\nService #{service} stopped"
        else
            puts "ERROR during #{service} stop"
        end
    end
end


def service_cleanup(service)

    _initdir = '/etc/init.d'
    _upstartdir = '/etc/init'
    _logdir = '/var/log'
    _bindir = '/usr/local/bin'

    Net::SSH.start($HOST, $USER, :keys => $RSA_KEY) do |ssh|
        cleaned = ssh.exec!("
            # /etc/init.d/vault
            if test -e #{_initdir}/#{service}; then
                sudo ls -l #{_initdir}/#{service}
            else
                echo \"File #{_initdir}/#{service} not found, skip\"
            fi

            # /etc/init/vault
            if test -e #{_upstartdir}/#{service}; then
                sudo ls -l #{_upstartdir}/#{service}
            else
                echo \"File #{_initdir}/#{service} not found, skip\"
            fi

            # /var/log/vault
            if test -e #{_logdir}/#{service}.log; then
                sudo ls -l #{_logdir}/#{service}.log
            else
                echo \"File #{_initdir}/#{service} not found, skip\"
            fi

            # /usr/local/bin/vault
            if test -e #{_bindir}/#{service}; then
                sudo ls -l #{_bindir}/#{service}
            else
                echo \"File #{_initdir}/#{service} not found, skip\"
            fi

            ")
        puts cleaned
    end
end

def service_destroy(service)
    # 1 if service up and running
    # 0 otherwise
    s_status = service_check(service)

    if s_status.to_i == 1
        puts "Stopping #{service} on the #{$HOST}"
        service_stop(service)
    else
        puts "\nService #{service} already stopped: #{service_check(service)}"
    end

    print "\nRemoving #{service} data in #{$HOMES[service]}...\n\n"
    service_delete($HOMES[service])

    print "\nCleaning up after service.\n\n"
    service_cleanup(service)

end

for service in $HOMES.each_key
    service_destroy(service)
end

And it's execution:

$ ./scripts/destroy.rb setevoy.vault.local

[destroy.rb] Vault & Consul DESTROY started on the $HOST.

[destroy.rb] Working on the setevoy.vault.local

Service vault already stopped: 0

Removing vault data in /opt/vault/...

total 8
drwxr-xr-x 2 root root 4096 Feb 12 13:46 conf.d
drwxr-xr-x 2 root root 4096 Feb 12 13:38 data
0

Cleaning up after service.

-rwxr-xr-x 1 root root 919 Feb 12 13:38 /etc/init.d/vault
File /etc/init.d/vault not found, skip
-rw-r--r-- 1 root root 2687 Feb 15 13:44 /var/log/vault.log
-rwxr-xr-x 1 root root 33614224 Feb 12 13:35 /usr/local/bin/vault

Service consul already stopped: 0

Removing consul data in /opt/consul/...

total 12
drwxr-xr-x 2 root root 4096 Feb 12 13:46 conf.d
drwxr-xr-x 4 root root 4096 Feb 12 13:38 data
drwxr-xr-x 3 root root 4096 Feb 12 13:46 web-ui
0

Cleaning up after service.

-rwxr-xr-x 1 root root 935 Feb 12 13:38 /etc/init.d/consul
File /etc/init.d/consul not found, skip
-rw-r--r-- 1 root root 19883 Feb 15 15:55 /var/log/consul.log
-rwxr-xr-x 1 root root 20417720 Jan 14 21:33 /usr/local/bin/consul

Answer 1

1. Use Kernel#abort:

   puts "[#{$me}] ERROR: host to destroy must be in first argument. Exit."
   exit 1
   

   will behave the same as:

   abort "[#{$me}] ERROR: host to destroy must be in first argument. Exit."
   

2. Since it's a simple standalone script and not a space shuttle, you did OK that didn't use OOP (class, module), but methods defined in the way you did can't access variables just outside, so you had to use either global variables ($) or constants (upper case in identifier name) when possible (seems to be your case, so you could omit the dollar sign) to make them accessible from methods (def).
   You could use lambdas to resolve the scope issue and have some syntax sugar as a free bonus:

   service_destroy = lambda do |service|
     # ...
   end
   
   homes.keys.each(&service_destroy)