Reinstate ER diagram generation

changelog: Internal, Documentation, Generate the ER diagram on migrations

1. Diagrams are generated automatically during CI
2. Diagram can be customized using .erdconfig

We used to do this in the past and abandoned it in commit 47020c9,
as it was not maintained. This iteration should make it easier.

.erdconfig

@@ -0,0 +1,9 @@
+title: login.gov IdP entity-relationship diagram
+notation: bachman
+filename: idp_erd
+filetype: svg
+attributes:
+    - primary_keys
+    - foreign_keys
+    - content
+sort: false

.gitlab-ci.yml

@@ -746,3 +746,32 @@ deploy_eks:
     IMAGE_TAG: $CI_COMMIT_SHA
   rules:
     - if: $CI_COMMIT_BRANCH == "main"
+
+publish_er_diagram:
+  stage: .post
+  needs:
+    - job: build-ci-image
+  variables:
+    DOCKER_DB_HOST: db-postgres
+    POSTGRES_DB: identity_idp_test
+    POSTGRES_USER: postgres_user
+    POSTGRES_PASSWORD: postgres_password
+    POSTGRES_HOST_AUTH_METHOD: trust
+    RAILS_ENV: test
+  services:
+    - name: public.ecr.aws/docker/library/postgres:16.4
+      alias: db-postgres
+      command: ['--fsync=false', '--synchronous_commit=false', '--full_page_writes=false']
+  cache:
+    - <<: *ruby_cache
+  rules:
+    - if: $CI_COMMIT_BRANCH == "main"
+    - if: $CI_COMMIT_BRANCH == "vm-reinstate-erd"
+  image: "${ECR_REGISTRY}/idp/ci:${CI_COMMIT_SHA}"
+  script:
+    - *bundle_install
+    - bundle exec rake db:create db:migrate --trace
+    - bundle exec rails erd
+  artifacts:
+    paths:
+      - idp_erd.svg

Gemfile

@@ -116,6 +116,7 @@ group :development, :test do
   gem 'pry-doc'
   gem 'pry-rails'
   gem 'psych'
+  gem 'rails-erd'
   gem 'rspec', '~> 3.13.0'
   gem 'rspec-rails', '~> 7.0'
   gem 'rubocop', '~> 1.69.1', require: false

Gemfile.lock

@@ -253,6 +253,7 @@ GEM
       nokogiri (~> 1.10, >= 1.10.4)
       rubyzip (>= 1.3.0, < 3)
     cbor (0.5.9.8)
+    choice (0.2.0)
     chunky_png (1.4.0)
     coderay (1.1.3)
     coercible (1.0.0)
@@ -544,6 +545,11 @@ GEM
       activesupport (>= 5.0.0)
       minitest
       nokogiri (>= 1.6)
+    rails-erd (1.7.2)
+      activerecord (>= 4.2)
+      activesupport (>= 4.2)
+      choice (~> 0.2.0)
+      ruby-graphviz (~> 1.2)
     rails-html-sanitizer (1.6.1)
       loofah (~> 2.21)
       nokogiri (>= 1.15.7, != 1.16.7, != 1.16.6, != 1.16.5, != 1.16.4, != 1.16.3, != 1.16.2, != 1.16.1, != 1.16.0.rc1, != 1.16.0)
@@ -634,6 +640,8 @@ GEM
       rubocop-ast (>= 1.31.1, < 2.0)
     rubocop-rspec (3.2.0)
       rubocop (~> 1.61)
+    ruby-graphviz (1.2.5)
+      rexml
     ruby-progressbar (1.13.0)
     ruby-saml (1.17.0)
       nokogiri (>= 1.13.10)
@@ -833,6 +841,7 @@ DEPENDENCIES
   rack_session_access (>= 0.2.0)
   rails (~> 7.2.1)
   rails-controller-testing (>= 1.0.4)
+  rails-erd
   redacted_struct
   redis (>= 3.2.0)
   redis-session-store!

dockerfiles/idp_ci.Dockerfile

@@ -21,6 +21,7 @@ RUN apt-get update -qq && \
     nodejs \
     locales \
     google-chrome-stable \
+    graphviz \
     yarn
 
 RUN curl -Ss "https://storage.googleapis.com/chrome-for-testing-public/$(google-chrome --version | grep -Po '\d+\.\d+\.\d+\.\d+' | tr -d '\n')/linux64/chromedriver-linux64.zip" > /tmp/chromedriver.zip && \