Rolling Update for UpCloud Servers Using Terraform and Ansible

This tutorial demonstrates how to perform a rolling update for an application on a set of UpCloud servers. The process involves:

• Using Terraform to provision and manage the infrastructure on UpCloud.
• Employing Ansible to configure and update NGINX web servers on these instances.
• Implementing a rolling update strategy to modify the web content without downtime.
• Utilizing a load balancer to distribute traffic among the servers during the update process.

The rolling update allows you to change the web content (in this case, an animal-themed static page) across all servers gradually, ensuring continuous service availability.

Prerequisites

Install the required tools:

• Terraform
• Ansible
• upcloud-ansible-collection and UpCloud Python SDK (upcloud-api>=2.5.0)
• Git client

Follow these tutorials if you are unfamiliar with setting up these tools:

• How to get started with Terraform
• How to get started with Ansible Inventory

Example material used in this guide is available from the UpCloud Ansible Collection repository in Github. Clone the repository for further steps:

git clone https://github.com/UpCloudLtd/upcloud-ansible-collection.git

Setup

1. Set UpCloud credentials by using the upctl account login command or with environment variables. There are two methods to authenticate with the UpCloud API: using an API token (recommended) or using the username and password of a dedicated UpCloud subaccount. See our API Tokens guide for full details on creating and managing tokens, or our HTTP Basic authentication guide for subaccount creation.

   # Option 1 (recommended): Use an API token
   export UPCLOUD_TOKEN="ucat_..."
   
   # Option 2: Use username and password
   export UPCLOUD_USERNAME="your-username"
   export UPCLOUD_PASSWORD="your-password"

2. Enter the example directory and create a set of UpCloud servers:

   cd upcloud-ansible-collection/examples/inventory-rolling-update/resources
   terraform init
   terraform apply
   cd ..

3. Install and configure NGINX on the servers created in the previous step:

   # Initial configuration
   ansible-playbook configure-webserver.yml --extra-vars "serial_override=0"
   
   # Update with specific tag
   ansible-playbook configure-webserver.yml --extra-vars "animal=tiger"

4. Monitor updates:

   watch -n 0.75 curl -s $(terraform -chdir=resources output -raw lb_url)

5. Cleanup:

   terraform -chdir=resources destroy