Is Terrantula a TACOS?
No. TACOS — Terraform Automation and Collaboration Software: Terraform Cloud, Spacelift, env0, Scalr, Atlantis, and friends — host or execute Terraform runs. They compete on running runs well: concurrency, policy checks, drift schedules, run UIs.
Terrantula sits above that layer and integrates with all of them. It never hosts a runner, never stores state, never executes terraform apply (how). What it owns is the layer no TACOS has: a typed model of the fleet your runs produce — which tenant is on which cluster, how much capacity is left, what order a teardown must happen in, and the placement decision for the next instance.
The practical test: a TACOS answers "did this run succeed?" Terrantula answers "where should the next tenant land, are we at the ceiling, and did the churned customer's stack actually get removed?"
So you need both? You already have the bottom layer — even "bare Terraform + GitHub Actions + S3 state" counts, and it's a first-class integration here. Terrantula adds the fleet layer on whatever you run:
- Terrantula + Terraform Cloud
- Terrantula + Atlantis
- Terrantula + Atmos
- Bare TF + GitHub Actions on-ramp
Not for you if you're shopping for a runner. Pick a TACOS (or keep GitHub Actions); come back when you're stamping the same Terraform for the Nth tenant, account, or team.