Ruby how to get my private and public IP address

Ok,
you've just deployed your newest ruby app on a bunch of servers, and you need that this app knows the IP address of the server where it's running.

I've read some bizarre ways ("Get your local IP address" or "Get your local IP address") to do this, such as opening an UDP socket and inferring it from the interface used to route the packet.
With the Socket class you may do this more easily and also get the benefit of having useful Addrinfo objects and you are able to distinguish easily between public and private interfaces.

First of all:

Socket::ip_address_list

returns the Array of Addrinfo objects with all your interfaces (it deals with both IPv4 and IPv6).

You can then filter them using the standard Enumerable methods select() and detect() along with these Addrinfo methods:

Addrinfo#ipv4?
Addrinfo#ipv6?
Addrinfo#ipv4_private?
Addrinfo#ipv4_loopback?
Addrinfo#ipv4_multicast?

and convert them to string in dotted notation with

Addrinfo#ip_address

as in:

def all_my_ipv4_interfaces

socket.ip_address_list.select{|intf| intf.ipv4?}

end

def my_loopback_ipv4

socket.ip_address_list.detect{|intf| intf.ipv4_loopback?}

end

def my_first_private_ipv4

socket.ip_address_list.detect{|intf| intf.ipv4_private?}

end

def my_first_public_ipv4

socket.ip_address_list.detect{|intf| intf.ipv4? and !intf.ipv4_loopback? and !intf.ipv4_multicast? and !intf.ipv4_private?}

end

all_my_ipv4_interfaces

=> [#<Addrinfo: 127.0.0.1>, #<Addrinfo: 10.212.142.73>, #<Addrinfo: 62.127.4.80>]

my_first_private_ipv4

=> #<Addrinfo: 10.212.142.73>

my_first_public_ipv4.ip_address

=> "62.127.4.80"

My CSS stylesheet for Ruby on Rails syntax highligthing

As my very first post, I would like to share with you the CSS stylesheet I use to format Ruby snippets.
If you need a CSS stylesheet ready to be applied to your html code block, or you simply like my ruby formatting color schema, you can take it!

div.rb-code {
 padding:1em 1em 1em 1em;
 border:0.2em groove #000000;
 font-family:Andale Mono,monospace;
 font-size:1.2em;
 color:#CC9900;
 background-color:#3A3A3A;
 overflow:auto;
 z-index:1;
}
div.rb-block-def {}
div.rb-block-exe {}
div.rb-code div.tab { padding-left:1.4em; }
div.rb-code .attribute { color:#FFFF66; }
div.rb-code .argument { color:#FFFF00; font-style:italic; }
div.rb-code .class-parent { color:#00FF00; }
div.rb-code .class { color:#FF00FF; font-weight:bold; }
div.rb-code .comment { color:#FFFFFF; }
div.rb-code .constant { color:#FF9966; }
div.rb-code .keyword { color:#FF8000; text-decoration:underline; }
div.rb-block-def .method { color:#FF00FF; }
div.rb-code .module { color:#A020F0; font-weight:bold; }
div.rb-code .number { color:#00FFFF; font-weight:bold; }
div.rb-code .regexp { color:#FF0000; }
div.rb-code .string { color:#99CCFF; }
div.rb-code .symbol { color:#CCFF66; }
div.rb-code .var { color:#FFFF66; font-weight:bold; }
div.rb-block-exe .command { color:#99CCFF; font-weight:bold; }
div.rb-block-exe .evaluation { color:#F0F0F0; font-size:0.8em; }
div.rb-block-exe .prompt { color:#CC9900; }

To use it, simply place all your code snippet between <DIV class='rb-code'>...</DIV>, and then wrap inside the appropriate <SPAN>...</SPAN> block the portions you need to highligth.

You can distinguish def blocks and executable blocks placing them inside a <DIV class='rb-block-def'> or a <DIV class='rb-block-exe'>

To ident a block, put it inside another <DIV class='tab'>

Look at the following example:

<DIV class='rb-code'>  
<DIV class='rb-block-def'>
<DIV><SPAN class='keyword'>class</SPAN> <SPAN class='class'>Person</SPAN></DIV>
<DIV class='tab'>
<DIV><SPAN class='keyword'>def</SPAN> <SPAN class='method'>speak_now</SPAN>(<SPAN class='argument'>thought</SPAN>)</DIV>
<DIV class='tab'>
<DIV>puts <SPAN class='var'>thought</SPAN></DIV>
</DIV>
<DIV><SPAN class='keyword'>end</SPAN></DIV>
</DIV>
<DIV><SPAN class='keyword'>end</SPAN></DIV>
</DIV>
</DIV>

it will be shown as:

class Person

def speak_now(thought)

puts thought

end

end