Getting IP address of the AWS instance when using packer and ansible

Question

I am building an AMI image on AWS using packer and Ansible. My end goal is to have an AMI image such that when it is built into an EC2 instance, it has my web app running. For me to reach my end goal, I need to configure Nginx server in my AMI. My challenge is I don't have any idea how to get the IP address of the EC2 instance and use it to configure Nginx server. Here is my current configuration of Nginx file:

server {
    listen 80;
    server_name {{ ansible_default_ipv4.address }};

    location / {
        include uwsgi_params;
        uwsgi_pass unix:/home/ubuntu/Yummy-Recipes/Yummy-Recipes-Ch3/yummy-recipes.sock;
    }
}

server_name should hold the value of the EC2 instance it is running on. If you would like to know more about my code than please feel free to visit my repository on GitHub.

Any help will be highly appreciated.

@nbari Wow! Thanks! Didn't knew about that. Will try it out! — Harith, May 20 '18 at 07:18

score 2 · Accepted Answer · answered May 20 '18 at 08:25

2

Since you are creating an AMI you can't use ansible at (image) build time to configure this. Later when you launch a new instance from the created image the IP and hostname will be different.

Instead you should add a cloud-init script that will update the config file everytime a new instance will be launched from the image. You do this by adding a script in /var/lib/cloud/scripts/per-instance/ see cloud-init documentation

answered May 20 '18 at 08:25

Rickard von Essen

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So I add a script there using **ansible**? And will it run by itself? – Harith May 20 '18 at 10:44
1

Yes you add it there with Ansible and cloud-init will run it on the first boot of a new instance. – Rickard von Essen May 20 '18 at 10:45
Do I need to install **cloud-init** on the AMI using ansible? If yes, then how? – Harith May 20 '18 at 15:12
It's a standard package, but it should already be installed in the base AMI. – Rickard von Essen May 20 '18 at 15:44
so you mean I don't need to install it? – Harith May 20 '18 at 15:57
1

Yes, you shouldn't have to. But double check the installed packages. – Rickard von Essen May 20 '18 at 16:12
So I copied a script file to the folder you prescribed, but the script did not run when I instantiated the instance. – Harith May 21 '18 at 18:24
Check your logs. – Rickard von Essen May 21 '18 at 18:29
there is nothing about my script – Harith May 21 '18 at 18:49

score 0 · Answer 2 · answered May 20 '18 at 11:20

You can also use an elastic ip. Assuming that you're going to use your image to spin up just one instance, AWS has an option of an elastic ip which is basically a static ipv4 address. Setup one for your account in your preferred region and then associate it with your instance or network interface at the time of provisioning. Your nginx configuration file should look like this

server {
listen 80;
server_name <your_elastic_ip>;
...
}

Getting IP address of the AWS instance when using packer and ansible

2 Answers2