[pfix]

What Terraform brings to the table for us is the capability of calculating the delta of "I want those resources" and "these resources are actually there" by having a separate state stored e.g. as JSON in S3 to compare your code, the world as it should be and how it actually is. That takes away reimplementing that.

Why just not writing idempotent resource creation? Terraform also uses this to calculate a "plan" that shows the diff of your changes with reality, which really helps to figure out what happens to your RDS when executing, especially when more abstraction (in form of Terraform modules) is involved.

We used Terraform also in a situation where writing custom code would be "prettier" but would have required to write this actual vs desired state code ourselves and could save us the work of doing so.

The DSL of Terraform is sometimes quite cumbersome though as it's derived JSON and not some actual programming language.

[SOLAR_FIELDS]

To your last point, yeah, I think Terraform gets really painful when you have to do something involving derived values in a loop. Also just computed values in general there is not a great story around (which is not necessarily terraforms fault, but rather a symptom of what you are provisioning).

A simple example of what I mean by computed values is that let’s say you want to provision a k8s cluster on top of a network. The k8s provider might want the network name/id which you could normally get by setting it upstream. The problem is you can’t plan the network creation and k8s cluster in a single pass because you don’t get the network name until it’s actually provisioned. You actually need to apply the network tf first to get the inputs you need to plan the cluster. Meaning not only do you need to run tf twice, you also can’t E2E plan infra provisioning

If anyone has a solution/pattern for the above (or more generally how to chain these modules together when this limitation exists) I’m all ears

[msmith]

Can your example be solved by having the k8s cluster resource reference the network resource’s “name” attribute?

Doing that allows Terraform to create both resources in one plan/apply step, and it also helps Terraform understand the dependency between the resources so that they are created in the correct order.

[samsquire]

My hobby solution was to represent an environment as an ordered graph that you can spin up.

https://devops-pipeline.com/