feat: execute service as distributed erlang (#96)

To create a cluster with distributed nodes, the following changes were made:

* Use [`dns_cluster`][0] to execute distributed nodes
* Add _script_ to execute distributed nodes locally

Also, improve local execution by:

* Use [`mix release`][1] to make easier [deploy `phoenix`][2]
* Use [`compose watch`][3] to synchronize code from the host with the service

Some minor improvements:

* Ignore files and folders in git and docker
* Remove boilerplate comments

[0]: https://github.com/phoenixframework/dns_cluster
[1]: https://hexdocs.pm/mix/Mix.Tasks.Release.html
[2]: https://hexdocs.pm/phoenix/releases.html
[3]: https://docs.docker.com/compose/how-tos/file-watch/

Co-authored-by: Joao P Dubas <joao.dubas@gmail.com>
Reviewed-on: #96
Co-authored-by: Joao P Dubas <joao.dubas+gitea@gmail.com>
Co-committed-by: Joao P Dubas <joao.dubas+gitea@gmail.com>

docker-compose.yml

@@ -7,59 +7,52 @@ services:
     environment:
       POSTGRES_USER: &db_user postgres
       POSTGRES_PASSWORD: &db_pass postgres
-      POSTGRES_DB: &db_name postgres
+      POSTGRES_DB: postgres
     volumes:
       - './priv/docker/postgres/init.sql:/docker-entrypoint-initdb.d/init.sql'
       - 'db_data:/var/lib/postgresql/data'
     restart: unless-stopped
   app:
-    image: &app_image 'joaodubas/ex_trainer:${EX_TRAINER_TAG:-dev}'
+    image: 'joaodubas/ex_trainer:${EX_TRAINER_TAG:-dev}'
     build:
       target: builder
       context: .
-    hostname: app
+      args:
+        BUILD_MIX_ENV: dev
+    hostname: &app_host ex_trainer
     depends_on:
       - db
     init: true
-    environment: &app_environment
+    develop:
+      watch:
+        - path: ./
+          ignore:
+            - ./build/
+            - ./deps/
+          target: /opt/app
+          action: sync
+        - path: ./config/
+          target: /opt/app
+          action: sync+restart
+        - path: ./lib/wabanex/application.ex
+          target: /opt/app
+          action: sync+restart
+        - path: ./mix.exs
+          target: /opt/app
+          action: sync+restart
+        - path: ./mix.lock
+          action: rebuild
+    environment:
+      DNS_CLUSTER_QUERY: *app_host
       POSTGRES_HOST: *db_host
       POSTGRES_USER: *db_user
       POSTGRES_PASS: *db_pass
       POSTGRES_NAME: wabanex_dev
-    volumes: &app_volumes
-      - '.:/opt/app'
-      - 'app_build:/opt/app/_build'
-      - 'app_deps:/opt/app/deps'
     working_dir: /opt/app
     restart: unless-stopped
-    entrypoint: sleep
-    command: infinity
-  db_setup:
-    image: *app_image
-    depends_on:
-      - db
-    profiles:
-      - setup
-    environment: *app_environment
-    volumes: *app_volumes
-    restart: 'no'
-    command: |
-      mix ecto.setup \
-      && MIX_ENV=test mix ecto.setup
-  db_migrate:
-    image: *app_image
-    depends_on:
-      - db
-    profiles:
-      - migrate
-    environment: *app_environment
-    volumes: *app_volumes
-    restart: 'no'
-    command: |
-      mix ecto.migrate \
-      && MIX_ENV=test mix.ecto.migrate
+    scale: 3
+    entrypoint: ./priv/docker/service/docker-entrypoint.sh
+    command: local-cookie
 
 volumes:
   db_data: {}
-  app_build: {}
-  app_deps: {}