# Thermograph — Terraform (host provisioning)

Terraform that **provisions and configures VPS hosts** and hands the app off to
`docker compose`, which pulls the published app image (built + pushed by the app
repo's CI) and runs it — no app source is ever built or checked out on a host.
By default it does *not* create servers: `modules/thermograph-host` is
SSH-provisioner-driven against a host that already exists. An optional
`modules/gcp-host` can additionally *create* the VM on GCP first (see "GCP
scaffold" below) — scaffold-only today, no live resources until you opt in.

## What it manages

One reusable module (`modules/thermograph-host`) is instantiated per host via
`for_each` (`main.tf`'s `local.all_hosts`, merging `var.hosts` — SSH-managed,
already-existing boxes — with any `var.gcp_hosts` Terraform created itself).
This config manages **two VPS hosts** today:

| key    | role   | VPS                     | branch    | domain            | notes                              |
|--------|--------|-------------------------|-----------|-------------------|------------------------------------|
| `prod` | prod   | NEW 48 GB / 12-core box (`169.58.46.181`) | `release` (of the APP repos — see `backend_image_tag` / `frontend_image_tag`) | `thermograph.org`      | Caddy TLS; sized up (8/8/4/16g) |
| `beta` | beta   | old box `75.119.132.91`                   | `main` (of the APP repo)    | `beta.thermograph.org` | Caddy TLS; also hosts Forgejo   |

Each host's own checkout on disk (`app_dir`, `git_branch`) is **this infra
repo**, not the app repo — the "branch" column above is which app-repo tag a
host is meant to track conceptually; the actual pinned versions are
`var.hosts[*].backend_image_tag` / `frontend_image_tag` (e.g. `"sha-<12 hex>"` each —
the app is two separately-published images, `emi/thermograph-backend/app` and
`emi/thermograph-frontend/app`), since the host has no app checkout to derive a tag
from. The LAN dev server is **out of scope here** — it
builds from source via the app repo's `deploy/deploy-dev.sh` (a self-hosted
Forgejo Actions runner), not Terraform.

Per host, over SSH provisioners, Terraform:

- installs Docker + the compose plugin if missing;
- configures a `ufw` firewall (22/80/443 always; on a host with **no** domain it also
  opens the app port `8137`);
- ensures the git checkout at `app_dir` exists (clones **this repo** on a fresh box)
  and resets it to the host's `git_branch`;
- renders `/etc/thermograph-topology.env` from Terraform variables (non-secret sizing
  only — `WORKERS`/`APP_CPUS`/`DB_CPUS`/`DB_MEMORY`/etc.), then runs
  `deploy/render-secrets.sh` (from that same freshly-synced checkout) to render
  `/etc/thermograph.env` from the SOPS+age vault — **Terraform itself never sees or
  carries an app secret** (see "Secrets" below);
- for a host **with** a domain, installs a rendered Caddyfile and reloads Caddy;
- brings the stack up on the explicit per-service tags (exports `BACKEND_IMAGE_TAG` /
  `FRONTEND_IMAGE_TAG` for the compose file): `docker login` to the registry,
  `docker compose <-f each compose file> pull backend frontend`, then
  `... up -d --remove-orphans`, running docker as root with both env files sourced;
- health-checks `http://127.0.0.1:8137/`.

A change to the rendered topology env, the compose files, the branch, the app image
tag, or the sizing flips the `null_resource` trigger and re-runs the provisioners on
next apply.

## GCP scaffold (no live resources)

`modules/gcp-host` can create a GCE VM (+ a dedicated VPC, subnet, and a firewall
opening 22/80/443) instead of assuming the host already exists — see `main.tf`'s
`module.gcp_vm`. It contributes *nothing* to provisioning: its only output
(`external_ip`) feeds into the exact same `thermograph-host` module every
SSH-managed host uses, so there's one provisioning path regardless of how a
host came to exist. `var.gcp_hosts` defaults to `{}`, so by default no
`google_*` resource is ever planned and the `google` provider is never
invoked — `terraform plan`/`validate` succeed with no GCP credentials
configured at all. To actually use it: populate an entry in
`terraform.tfvars` (see the commented example in
`terraform.tfvars.example`) and authenticate via `gcloud auth
application-default login` or `GOOGLE_APPLICATION_CREDENTIALS`. This is the
same create-then-provision composition a future Proxmox module (the
architecture doc's longer-term target — see §6/§9 there) would use.

### Container sizing is env-driven

`docker-compose.yml` reads `WORKERS`, `APP_CPUS`, `DB_CPUS`, and `DB_MEMORY` from the
environment (defaults `4 / 4 / 2 / 8g`, identical to before). Terraform sets them per
host through `/etc/thermograph-topology.env`, so the big prod box can run larger caps
without a compose edit. The Postgres *internal* memory budget (`shared_buffers`,
`effective_cache_size`, `work_mem`, `maintenance_work_mem`) is derived from the same
`DB_MEMORY` by `deploy/db/init/20-tuning.sh` — so raising `db_memory` scales the
container cap and the tuning together (prod 16g → shared_buffers 4 GB). The tuning
applies on a fresh DB volume; on an existing volume re-run it by hand (see the script
header).

## Prerequisites

- Terraform >= 1.6 (v1.15 is installed).
- SSH key access to **both** hosts as a **sudo-capable** user (the live boxes use the
  dedicated `agent` account, `~/.ssh/thermograph_agent_ed25519` — see
  `deploy/provision-agent-access.sh`). Point `ssh_private_key_path` at that key (`~`
  is expanded).
- The hosts are Debian/Ubuntu with `apt` and outbound internet (Docker/Caddy installs
  pull from the network). Docker may already be present — installs are conditional.
- For the `prod` host: DNS for `thermograph.org` must point at the new box before apply,
  or Caddy's first-request cert issuance will fail.

## Use

```sh
cd terraform
cp terraform.tfvars.example terraform.tfvars   # then edit: real IPs + secrets
terraform init
terraform plan
terraform apply
```

Target one host with `-target='module.host["beta"]'` if you want to apply to just one.

## Secrets

App secrets (`POSTGRES_PASSWORD`, `THERMOGRAPH_AUTH_SECRET`, VAPID keys,
`REGISTRY_TOKEN`, Discord/SMTP credentials, …) are **not** Terraform variables
— they live in the git-native SOPS+age vault at `../deploy/secrets/*.yaml`
(committed, encrypted) and are rendered into `/etc/thermograph.env` at deploy
time by `../deploy/render-secrets.sh`, which the provisioner's deploy step
runs from the freshly-synced checkout. Terraform only renders the non-secret
`/etc/thermograph-topology.env` (sizing/routing). See
`../deploy/secrets/README.md` to rotate a secret or add a new one — it's a
`sops edit` + commit + deploy, no Terraform apply involved.

`om_rclone_conf` (object-storage bucket credentials for the self-hosted ERA5
archive) is the one exception still supplied via Terraform, in
`terraform.tfvars` — folding it into the vault too is a reasonable future
step, not done here.

## Local state

The backend is **local**: `terraform.tfstate` is written next to the config.
It's gitignored (`terraform/.gitignore` and the root `.gitignore`) — keep it
off shared disks and back it up somewhere private. `terraform.tfvars` is
likewise gitignored (it may carry a `repo_url` credential and always carries
`om_rclone_conf`); only `terraform.tfvars.example` (dummy values) is
committed. `.terraform.lock.hcl` **is** committed so provider versions are
pinned across machines.

## WARNING — applying against live prod

`terraform apply` runs `remote-exec` **on the server**: it resets the checkout to the
branch, renders topology config + secrets, and runs `docker compose pull && up -d`
(pulling the pinned `backend_image_tag` / `frontend_image_tag` and recreating
containers — a brief app restart).
Against the live production host this is a real deploy. Review the plan, apply in a
maintenance window, and prefer `-target` to touch one host at a time.

This is **separate from the Postgres data cutover** in `deploy/POSTGRES-MIGRATION.md`.
Terraform provisions the host and starts the stack; it does **not** migrate the
SQLite→Postgres accounts data. Sequence them deliberately: for a first cutover on a
host, follow the migration doc's freeze/backup/copy steps around the point where
Terraform brings the stack up — don't let Terraform recreate containers mid-migration.

## Assumptions / notes

- **beta has no public domain by default.** With `compose_files = ["docker-compose.yml"]`
  the app binds `127.0.0.1:8137` (loopback), so opening the port in `ufw` alone does not
  expose it. Reach beta via an SSH tunnel, or set `domain = "beta.thermograph.org"` (adds
  Caddy TLS) — or add the `0.0.0.0`-publishing dev overlay to `compose_files` — to make
  it reachable. `COOKIE_SECURE` is auto-set to `0` when there's no domain (a Secure
  cookie is never sent over plain HTTP) and `1` behind Caddy TLS.
- The rendered Caddyfile only reverse-proxies the app. The repo's `deploy/Caddyfile`
  additionally serves the `emigriffith.dev` portfolio and legacy redirects; those are
  host-specific and not templated here.
- Provisioner-based by design: the hosts already exist, so this is not a
  create-from-scratch cloud config. Re-applying is idempotent (installs are guarded,
  `git reset --hard`, compose `up` reconciles).
