[How to] Preserve an External IP Address of GCP Compute Engine
How to series
Using Static IP for External IP Addresses
Managing IP addresses effectively is critical for ensuring the reliability and accessibility of your applications deployed on the cloud. In Google Cloud Platform (GCP), Compute Engine instances are automatically assigned ephemeral (temporary) external IP addresses when they are created. However, these ephemeral IPs are not persistent, and if you stop and restart your instance, the external IP is reassigned, which may disrupt services dependent on a consistent IP address.
Static IP addresses can be used to solve this.
Why Static IP Addresses?
Static IPs are fixed, publicly accessible IP addresses assigned to your resources. They remain constant, even if the associated instance is stopped and restarted. This makes them ideal for use cases requiring:
- Reliable access points for APIs or applications.
- DNS configurations pointing to a fixed IP.
- IP whitelisting for security purposes.
Here’s a step-by-step guide to reserve and attach a static IP address to a Compute Engine instance.
1. Create a Compute Engine Instance
- In the GCP Console, navigate to Compute Engine > VM Instances.
- Click Create Instance and configure it according to your requirements.
- Note the External IP address of your instance. This is the ephemeral IP assigned by GCP, which will change if you stop and restart the instance.
2. Observe the Behavior of Ephemeral IP Addresses
- Stop the instance by clicking on the Stop button.
- After the instance stops, notice that the External IP is no longer listed.
- Restart the instance, and you’ll see a new ephemeral External IP address assigned.
This demonstrates that ephemeral IPs are not persistent across instance lifecycle events.
3. Reserve a Static External IP Address
To ensure the same external IP address is retained:
- Navigate to VPC Network > IP Addresses in the GCP Console.
- Click on Reserve External IP Address.
4. Configure the Static IP
- Name: Give your static IP a descriptive name (e.g.,
my-static-ip). - Type: Keep the default as Regional unless you have specific requirements for a Global IP.
- Attached To: Select your Compute Engine instance from the dropdown.
5. Save and Verify
- Save the configuration.
- Go back to VM Instances, and verify that the static IP is attached to your instance.
- Stop and restart the instance to confirm the static IP persists.
Things to Remember
- Flexibility: You can detach a static IP from one instance and attach it to another as needed.
- Cost Implications:
- GCP charges for static IP addresses even when not in use.
- The costs for an unused static IP are higher compared to an active/in-use static IP.
Alternative Approaches
While static IPs solve the issue for individual instances, for high-availability setups or multiple instances, you may want to consider other options like Load Balancers. We’ll cover that in another blog.
Conclusion
Static IP addresses in GCP provide a straightforward and reliable way to ensure your applications remain accessible via a consistent external IP. While this incurs a cost, the benefits often outweigh it, especially for production workloads requiring stability.
Follow these steps to configure your static IPs and say goodbye to the uncertainty of ephemeral addresses!
A Note from the writer…
Welcome to my How-to Tech Blog Series, where I break down technical tasks into simple, actionable steps. Whether you’re coding in your favorite language, navigating the complexities of cloud technologies, or tackling day-to-day programming challenges, this series aims to provide clear and concise solutions. Stay tuned for quick guides that empower you to solve problems and enhance your skills!
