DEV Community

Cover image for 🔗 AWS 110: Making it Permanent - How to Associate an Elastic IP with an EC2 Instance
Hritik Raj
Hritik Raj

Posted on

🔗 AWS 110: Making it Permanent - How to Associate an Elastic IP with an EC2 Instance

#aws #networking #devops #100daysofcloud

AWS

📍 AWS Networking: Giving Your Server a Static Identity

Hey Cloud Networkers! 👋

Welcome to Day 10 of the #100DaysOfCloud Challenge: Associate Elastic IP! We are reaching a milestone in our migration journey with KodeKloud Engineer. We have a server, and we have a static IP address. Today, we are finally linking them together.

Our mission: Associate the Elastic IP named datacenter-ec2-eip with the EC2 instance named datacenter-ec2 in the us-east-1 region.

1. Introduction: The Power of Association 💡

Think of your EC2 instance as a smartphone and the Elastic IP (EIP) as a permanent phone number. Without an EIP, every time you "restart" your phone, your number changes. By associating an EIP, you ensure that no matter what happens to the hardware, your "number" stays the same.

  • Dynamic vs. Static: Standard Public IPs are dynamic and change on reboot. EIPs are static and stay with your account.
  • Association: This is the act of pointing the EIP to a specific instance or network interface.
  • Why it Matters: This is essential for DNS records. If your IP address keeps changing, your website or service will constantly go offline for users!

Let's make this connection permanent! 🔗

2. Step-by-Step Guide: Attaching the EIP to datacenter-ec2

We will use the AWS Management Console to perform this association.

Step 2.1: Locate your Elastic IP

  1. Log in to the AWS Console and navigate to the EC2 Dashboard.

  1. In the left sidebar, under "Network & Security", click on "Elastic IPs".

  1. Look for the EIP named datacenter-ec2-eip.

Step 2.2: Associate the Address

  1. Select the datacenter-ec2-eip checkbox.
  2. Click the "Actions" button and select "Associate Elastic IP address".

  1. In the Instance search box, find and select the instance named datacenter-ec2.
  2. Leave the Private IP address as the default (the primary private IP of the instance).
  3. Click "Associate".

Step 2.3: Verify the Connection

  1. Go to the EC2 Dashboard and click on "Instances".
  2. Select datacenter-ec2.
  3. In the Details tab below, look for the "Public IPv4 address". It should now exactly match the Elastic IP you just associated!

Success! Your server now has a permanent, static public identity. 🎉

If you cannot find an Elastic IP named datacenter-ec2-eip, it likely hasn't been allocated to your account yet or was created without that specific Name tag.

You will need to Allocate a new address and name it before you can associate it with your instance.

Allocate and Name the Elastic IP

  1. In the EC2 Dashboard, go to Network & Security > Elastic IPs.
  2. Click the orange Allocate Elastic IP address button.
  3. Leave the default settings (Amazon's pool of IPv4 addresses).
  4. Scroll down to the Tags section.
  5. Click Add new tag:
  6. Key: Name
  7. Value: datacenter-ec2-eip
  8. Click Allocate. You should now see the IP listed with the correct name.

👉Allocating Elastic IPs

3. Key Takeaways 📝

  • Immediate Update: The change happens almost instantly. Once associated, your server is reachable at the new IP.
  • One-to-One: An Elastic IP can be associated with only one instance or network interface at a time.
  • Decoupling: You can disassociate an EIP from a failed instance and move it to a healthy one in seconds.

4. Common Mistakes to Avoid 🚫

  1. Reassociation Costs: AWS generally doesn't charge for an EIP that is associated with a running instance. However, if you keep an EIP but don't associate it, you will be charged!
  2. Public IP Loss: When you associate an EIP, the instance's original dynamic Public IP is released back into the AWS pool. You cannot get that old dynamic IP back.
  3. Region Lock: You can only associate an EIP with an instance in the same AWS region.

5. Conclusion + Call to Action! 🌟

By linking our static IP to our datacenter server, we've taken a huge step toward production stability. This is how professional DevOps teams ensure high availability and reliable connectivity.

Are you still going strong with the 100 Days of Cloud Challenge?

  • 💬 Let’s connect on LinkedIn: Let's discuss cloud networking and DNS best practices! 👉 Hritik Raj
  • ⭐ Support my journey on GitHub: Check out my scripts and documentation for the full challenge. 👉 GitHub – 100 Days of Cloud

Top comments (0)