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I'm assigning automatically a secondary private IPv4 address during launch of my instances. To configure Ubuntu to recognize this secondary IP I need to run

ip addr add 10.0.1.15/24 dev eth0

To access the primary private IP address I have found this command (described in the AWS Docs and in figaros question):

curl http://169.254.169.254/latest/meta-data/local-ipv4

But how can I get the secondary IP address to run the ip command automatically on startup? For Amazon Linux Systems there's the ec2-net-utils package wich can handle this automatically.

benedikt
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    I typed "ubuntu run command on startup" into Google and found many results. I'd have told you what they were, but it depends on whether you're using systemd or something else. [This question](https://askubuntu.com/questions/919054/how-do-i-run-a-single-command-at-startup-using-systemd) will probably solve it for you. – Tim Nov 14 '17 at 19:10
  • Thank you Tim, but I have no problem to run my scripts on startup and I know how to do that. I need a way to get the secondary private IP address of my Amazon EC2 instance, so I can use it within my scripts. There`s a solution for the primary IP address in the AWS Docs but not for the secondary IP. – benedikt Nov 15 '17 at 08:35

2 Answers2

6

You can get secondary address with 2 commands.

Get mac address of your network interface

MAC=`curl http://169.254.169.254/latest/meta-data/mac`

Get all IP addresses for this mac address

curl http://169.254.169.254/latest/meta-data/network/interfaces/macs/${MAC}/local-ipv4s
antrost
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4

Because of antrost answer (his curl request returns all ip addresses) I was able to write the following bash script wich returns the secondary private IP only and configures Ubuntu to recognize it: 

#!/bin/bash
MAC=`curl -s http://169.254.169.254/latest/meta-data/mac`
ADDRESSES=`curl -s http://169.254.169.254/latest/meta-data/network/interfaces/macs/${MAC}/local-ipv4s`
arr=($ADDRESSES)
if [ ${#arr[@]} -ge 2 ];
then
  ip addr add ${arr[1]}/24 dev eth0
fi
benedikt
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