Complete instructions to deploy Tessera GCP (#86)

* read environment variables

* add instructions

* s/trillian-tessera/tessera because otherwise names are too long

* better names and move documentation around

* s/us-east1/us-central1

* leave defaults set to current values

* tidy things up

* EnglishIsHard

deployment/README.md

@@ -14,13 +14,5 @@ Deploying these examples requires installation of:
 
 ## Deploying
 
-First authenticate via `gcloud` as a principle with sufficient ACLs for
-the project:
-```bash
-gcloud auth application-default login
-```
-
-Terraforming the project can be done by:
- 1. `cd` to the relevant `live` directory for the environment to deploy/change
- 2. Run `terragrunt apply`
+See individual `live` subdirectories.
 

deployment/live/example-gcp/README.md

@@ -0,0 +1,24 @@
+## Deployment 
+
+First authenticate via `gcloud` as a principle with sufficient ACLs for
+the project:
+```bash
+gcloud auth application-default login
+```
+
+Set your GCP project ID with:
+```bash
+export GOOGLE_PROJECT={VALUE}
+```
+
+Optionally, customize the GCP region (defaults to "us-central1"),
+and bucket name prefix (defaults to "example-gcp"):
+```bash
+export GOOGLE_REGION={VALUE}
+export TESSERA_BASE_NAME={VALUE}
+```
+
+Terraforming the project can be done by:
+ 1. `cd` to the relevant `live` directory for the environment to deploy/change
+ 2. Run `terragrunt apply`
+

deployment/live/example-gcp/terragrunt.hcl

@@ -3,9 +3,9 @@ terraform {
 }
 
 locals {
-  project_id = "trillian-tessera"
-  location   = "us-central1"
-  base_name   = "example-gcp"
+  project_id = get_env("GOOGLE_PROJECT", "trillian-tessera")
+  location   = get_env("GOOGLE_REGION", "us-central1")
+  base_name   = get_env("TESSERA_BASE_NAME", "example-gcp")
 }
 
 inputs = merge(