Monday, May 08, 2017

Oracle Linux - get your external IP in bash with ifconfig.me

Developing code that helps you in automatic deployments can be a big timesaver. Repeating tasks for installing servers, configuring them and deploying code on them is something which is more and more adopted by enterprises as part of DevOps and continuous integration and continuous deployment methods. When you use scripting for automatic deployment of your code in your own datacenter the beauty is that you fairly well know how the infrastructure looks and you have a fairly good view on how, for example, your machine will be accessible from the outside world. For example, if you deploy a server that has an external IP address on the outside of the network edge you should be able to determine this relatively easy even in cases where this IP is not the IP of your actual machine.

If you however provide scripting which you distribute you will not be able to apply the logic you might apply in your own network. For this you need some way to find out the external IP address. And, as stated, this can be something totally different than the IP which the machine actually has from your local operating system point of view.

The people at ifconfig.me have done some great work by providing a quick service to resolve this problem. ifconfig.me provide a service that will provide you all the information need (and more) in a manner that is easily included in bash scripting.

As an example, in case you would need your external IP to use in a configuration in your Oracle Linux deployment you could execute the below command:

[root@ce tmp]# curl ifconfig.me
172.217.17.46
[root@ce tmp]#

(do note, this is not my IP as I do not use a google webhost as one of my test machines). As you can see this is relative easy and to provide an example of how you could include this in a bash script you can review the below code snippet:

#!/bin/bash

 myIp=`curl -s ifconfig.me`

 echo $myIp

And, even though this is a very quick and easy solution to a problem you could face when you try to automate a number of steps while scripting the ifconfig.me provides more options. A number of options to get information from the "external" view are available and can all be found at the ifconfig.me website. However most important one is the ability to do a curl to ifconfig.me/all.json which will return a JSON based response with all the information in it. This makes it parsable. And to make it more easy, Oracle has included jq in the YUM repository which makes parsing JSON even more easy. An example of the JSON response from ifconfig.me is shown below (again.... using a fake google webhost and not my own private information.

{
 "connection": "",
 "ip_addr": "172.217.17.46",
 "lang": "",
 "remote_host": "ams16s29-in-f46.1e100.net",
 "user_agent": "curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.21 Basic ECC zlib/1.2.3 libidn/1.18 libssh2/1.4.2",
 "charset": "",
 "port": "54944",
 "via": "",
 "forwarded": "",
 "mime": "*/*",
 "keep_alive": "",
 "encoding": ""
}

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