The ramblings of a computer geek
Here’s a quick example of how you can use Terraform’s cidrsubnet function to streamline your use of IP Subnets and calculate a number of different subnets from a single CIDR range (or supernet). https://developer.hashicorp.com/terraform/language/functions/cidrsubnet Explaination The cidrsubnet function can be a bit weird when first looking at it. But we’re going to have an example … Read more
We use IaC (Infrastructure as Code) for the deployment and management of all cloud (AWS) workloads to ensure we can manage and update infrastructure and applications that are deployed in the cloud rapidily and on an ongoing basis, while maintaining flexibility, security and availability. However issues may occur when changes are made using automated processes, … Read more
Although you should be using a keypair for SSH authentication (and not exposing to the Internet), if you’re working with a throw-away or test instance you might just need password authentication to be enabled. Here’s how! Open the SSH configuration file. Set the line “PasswordAuthentication” to “yes”. Save and close. Restart the SSH daemon with: … Read more
A potential scenario is to have a single Terraform template repository where you need to manage AWS resources across a number of different AWS Accounts. However, because each AWS Account is the edge of its authentication and authorisation profile, there is a need to be able cross this boundary within your Terraform to be able … Read more
You can force a replacement of an AWS EC2 instance within Terraform by issuing the following command. The previous command “taint” has now been deprecated. Where your instance is called “My-Instance-1” within the Terraform template. When you run this the instance will be destroyed and replaced (as if it was the first time it was … Read more
AWS CloudFront allows you to front your application (be it on EC2 instances or REST API etc.) so you can provide high availability, caching and protection (with WAF) to the workload. When configuring your application, you don’t want the application to be directly accessible without using CloudFront, so therefore you need to add some restrictions, … Read more
Here’s a little oddity with AWS Route Tables within Terraform, if you want to remove all of the routes in a route table, you can’t just delete or comment them out, otherwise it treats them as if nothing has changed. See the below example, you comment/remove the routes, then in its place add a blank … Read more
During my learning of AWS and its deployment via Terraform, I came across an issue where my EC2 instances kept getting destroyed, even when no changes had been made to them. For example in the plan output: Notice the “# forces replacement” on the security_groups directive. Turns it it was quite a simple fix, although … Read more
From the AWS CLI you can easily see how big a AWS S3 Bucket, firstly login to the AWS CLI and then you can run the command:
Its always best to be using a user account authenticated via SSO (so you can have additional levels of security, e.g. MFA) on-top, and access AWS resources using a temporary Role (to provide the permissions). For most use cases e.g. interacting with the Web Console, using the CLI or performing development tasks via Cloudformation templates … Read more