make s3 buckets clearer

Author: sjpb

docs/opentofu-remote-state.md

@@ -109,10 +109,15 @@ per-checkout configuration is required.
 
 ### Initial setup
 
-1. Create an S3 bucket matching the current environment name:
+1. Create an S3 bucket with a name `${cluster_name}-${environment_name}-tfstate`
+   where:
+    - `CLUSTER_NAME` is defined in `environments/$ENV/tofu/main.tf`
+    - `$ENVIRONMENT_NAME` is the name of the environment directory
+
+    e.g.
 
     ```shell
-    openstack container create $(basename $APPLIANCES_ENVIRONMENT_ROOT)
+    openstack container create research-staging-tfstate
     ```
 
 2. Create `ec2` credentials:

environments/site/tofu/example-backends/s3.tf

@@ -4,12 +4,10 @@ variable "s3_backend_endpoint" {
     default = # Set this here
 }
 
-variable "s3"
-
 terraform {
     backend "s3" {
         endpoint = var.s3_backend_endpoint
-        bucket = basename(var.environment_root)
+        bucket = "${var.cluster_name}-${basename(var.environment_root)}-tfstate"
         key    = "environment.tfstate"
 
         # Reginon is required but not used in radosgw: