tf-state-worker

A Cloudflare worker to store and lock Terraform states in R2.

Why does this exist?

In the case of a new project in a serverless context, without any previous infrastructure (and so, without any Cloud object storage), it might be interesting to be able to store Terraform states in a remote backend to easily collaborate.

The worker does just that but uses Cloudflare object storage solution, R2.

But what about the S3 compatibility?

Indeed you're correct, it is possible to use the S3 backend to store states in Cloudflare R2 like this:

terraform {
  backend "s3" {
    bucket     = "tf-stats"
    key        = "foo.tfstate"
    endpoints  = { s3 = "https://xxx.r2.cloudflarestorage.com" }
    access_key = "xxx"
    secret_key = "xxx"
    region     = "us-east-1"

    skip_credentials_validation = true
    skip_region_validation      = true
    skip_requesting_account_id  = true
    skip_metadata_api_check     = true
    skip_s3_checksum            = true
  }
}

But not only is it verbose (and will never be supported officialy by Hashicorp) but it also does not support locking, which is pretty useful when working in a team.

Why the HTTP backend?

It appears that the remote backend also offers something similar but I can not find any documentation on implementing it and I'm not up to reverse-engineer it for the moment.

The HTTP backend was the simplest one to implement while also supporting locks.

Installation

You will need a Cloudflare account and an R2 bucket created, then you can run the following commands:

npm install
mv wrangler_example.toml wrangler.toml
# edit wrangler.toml to point to your R2 bucket
npx wrangler deploy

Wrangler is Cloudfare's tool to test and deploy workers.

Important

Note that by default, all requests will fail due to the default authorization method.

You can also execute npx wrangler dev to run a local worker and try it before deploying.

Usage

In your Terraform file:

terraform {
  backend "http" {
    address = "http://127.0.0.1:8787/states/foo"
    lock_address = "http://127.0.0.1:8787/states/foo"
    unlock_address = "http://127.0.0.1:8787/states/foo"
  }
}

or if you're using CDKTF:

import { HttpBackend } from 'cdktf';

const cfBackend = new HttpBackend(scope, {
  address: 'http://127.0.0.1:8787/states/foo',
  lockAddress: 'http://127.0.0.1:8787/states/foo',
  unlockAddress: 'http://127.0.0.1:8787/states/foo',
});

Where foo is the name of your state. If you wish to use it for remote states, here's an example:

data "terraform_remote_state" "foo" {
  backend = "http"
  config = {
    address = "http://127.0.0.1:8787/states/foo"
  }
}

and again if you're using CDKTF:

import { DataTerraformRemoteStateHttp } from 'cdktf';

const cfRemoteState = new DataTerraformRemoteStateHttp(scope, 'foo', {
  address: 'http://127.0.0.1:8787/states/foo',
});

Authentication

You can configure the authentication method to use. We are limited by what Terraform can send, it can either be Basic Auth header or query string.

Set the AUTH_PLUGIN variable to the plugin list and then depending on each plugin, the expected secrets or configuration.

Fail

Use the value fail to deny all operations. This is the default.

Noop

Use the value noop to allow all operations.

Warning

This is not recommended for security purpose unless you've secured the worker with something else. States can contain sensitive data and must be secured!

Basic

Use the value basic for a simple username/password check. Only one set of credentials is supported for the moment.

To configure this method, also set the secrets AUTH_BASIC_USERNAME and AUTH_BASIC_PASSWORD variables.

Migrate states

If you have existing states, you can either upload them on R2 interface to the states/ directory or use curl or any HTTP clients to push them through the API:

# Before changing the backend configuration
terraform state pull > backup.tfstate
curl -v -X POST http://foo:bar@127.0.0.1:8787/states/foo < backup.tfstate

In the case of a backend change, Terraform usually will prompt to run terraform init -migrate-state but your mileage may vary.

TODO

• Unit Tests
• e2e tests against a real Terraform
• Complete README
• Basic Authorization
• Advanced RBAC
• Audit logs / Webhooks
• MD5 of states