Terraform Tips and Tricks

Don't use Counts where possible as they are hard to track, and can lead to Resources being destroyed.
- Used named loops where ever possible.
- Counts are good for Feature Toggles.
Keep everything simple. Terraform is best as Infrastructure as Text.
Avoid using Remote State Data blocks, they make managing a pipeline super tricky and are a security issue.
Any secret touched by Terraform goes in the state file, remember this and treat the state file as sensitive.
Read the full name of the resource, and follow it in your file to help understand what is going wrong.
Terraform has 3 different types of loops
- Count for doing something equal to a length.
- for_each for looping in a resource.
- for for transforming locals.
debug does not do what you want, it only debugs TF application, nothing to do with your code.
state files are a good lifecycle boundary. If you run a destroy, it should pack up your whole project and nothing more or less.
ChatGPT and Copilot just don't get it.
Use Vars for all inputs, Locals for calculations
- This leads to less places to look for things to change.
use EOT descriptions to make Objects clearer, and to print nice to the CLI inputs and TFdocs
Use Object based Vars and outputs to give context and a good boundary for description.
- Grouping by lifecycle. Naming block has all you need for naming, no need to split over 5 places.
String interpolation is good for simple strings, otherwise concat() and join() leave more power for it to expand.
alt click in the shell is handy
- As well as following references
Modules are good for building a resource that has a singular lifecycle and intent.
- If you are struggling to not name a module the resource name, its too simple.
- If you are just copy / pasting the vars from the module to the root module, it probably shouldn't be a module.
Modules are not their own entity. Each Resource is measured by itself on the dependency graph.
Maps are sorted Lexographically, so they have the same constraints as Count based Loops. It is easy to remove the item from the middle and have everything change
override.tf and .auto.tfvars make working on plans locally super easy, and great for working on submodules.
- Mostly for troubleshooting larger projects in a personal scratch environment.