Remove artifact registry module from GCP conformance CI (#73)

* Remove artifact registry module from GCP conformance CI

* Update GCP SCTFE CI enviornment README

* Update GCP SCTFE CI enviornment README

* Update GCP SCTFE CI enviornment README

Author: roger2hk

deployment/live/gcp/ci/README.md

@@ -3,7 +3,7 @@
 ## Overview
 
 This config uses the [gcp/conformance](/deployment/modules/gcp/conformance) module to
-define a CI environment to run the SCTFE, backed by Trillian Tessera.
+define a CI environment to run the SCTFE on Cloud Run, backed by Trillian Tessera.
 
 At a high level, this environment consists of:
 - One Spanner instance with two databases:
@@ -13,6 +13,10 @@ At a high level, this environment consists of:
 - Secret Manager
 - Cloud Run
 
+### Automatic Deployment
+
+This GCP SCTFE conformance CI environment is designed to be deployed by the Cloud Build ([Terraform module](/deployment/modules/gcp/cloudbuild/), [Terragrunt configuration](/deployment/live/gcp/cloudbuild/prod/)).
+
 ### Manual Deployment
 
 First authenticate via `gcloud` as a principle with sufficient ACLs for
@@ -30,6 +34,8 @@ export GOOGLE_REGION={VALUE} # e.g: us-central1
 unset TESSERA_BASE_NAME
 ```
 
+You need an Artifact Registry repository to store container images; adapt the configs and commands below to use your registry of choice. The rest of these instructions assume that the repository is hosted on GCP, and called `${GOOGLE_REGION}-docker.pkg.dev/${GOOGLE_PROJECT}/docker-ci`. For reference, here's a [terraform module](/deployment/modules/gcp/artifactregistry/) you can use to set up such a registry.
+
 Build and push the Docker image to Artifact Registry repository:
 
 ```sh

deployment/modules/gcp/conformance/main.tf

@@ -2,13 +2,6 @@ terraform {
   backend "gcs" {}
 }
 
-module "artifactregistry" {
-  source = "../artifactregistry"
-
-  location   = var.location
-  docker_env = var.docker_env
-}
-
 module "storage" {
   source = "../storage"