feat: Isolate environment configuration from code

Move environment variable definitions from docker-compose.yml
to dedicated .env files. This change aligns with the 12factor.net
recommendation of storing configuration in the environment.

- Introduces .env.backend.example, .env.db.example, and
  .env.proxy.example to serve as templates.
- Modifies docker-compose.yml to use `env_file` for each service.
- Ensures that .env files are ignored by git.

Signed-off-by: Denys Fedoryshchenko <[email protected]>

Author: nuclearcat

.env.backend.example

@@ -0,0 +1,16 @@
+ALLOWED_HOSTS=["backend", "localhost"]
+DB_DEFAULT_PASSWORD_FILE=/run/secrets/postgres_password_secret
+DB_DEFAULT_HOST=cloudsql-proxy
+DB_DEFAULT_USER=${DB_DEFAULT_USER:-kernelci}
+DB_DEFAULT_NAME=${DB_DEFAULT_NAME:-kcidb}
+DJANGO_SECRET_KEY=${DJANGO_SECRET_KEY}
+DEBUG=${DEBUG:-False}
+DISCORD_WEBHOOK_URL=${DISCORD_WEBHOOK_URL}
+REDIS_HOST=redis
+GMAIL_API_TOKEN=gmail_api_token.json
+DASH_DB_NAME=${DASH_DB_NAME:-dashboard}
+DASH_DB_USER=${DASH_DB_USER:-admin}
+DASH_DB_PASSWORD=${DASH_DB_PASSWORD:-admin}
+DASH_DB_HOST=dashboard_db
+DASH_DB_PORT=${DASH_DB_PORT:-5432}
+USE_DASHBOARD_DB=${USE_DASHBOARD_DB:-False}

.env.db.example

@@ -0,0 +1,3 @@
+POSTGRES_USER=${DASH_DB_USER:-admin}
+POSTGRES_PASSWORD=${DASH_DB_PASSWORD:-admin}
+POSTGRES_DB=${DASH_DB_NAME:-dashboard}

.env.proxy.example

@@ -0,0 +1 @@
+PROXY_TARGET=http://backend:8000

.gitignore

@@ -2,6 +2,9 @@
 application_default_credentials.json
 .vscode
 .env
+.env.backend
+.env.db
+.env.proxy
 .idea
 
 # Data from docker volume that should only be automatically generated

docker-compose.yml

@@ -15,10 +15,8 @@ secrets:
 services:
     dashboard_db:
         image: postgres:17
-        environment:
-            - POSTGRES_USER=${DASH_DB_USER:-admin}
-            - POSTGRES_PASSWORD=${DASH_DB_PASSWORD:-admin}
-            - POSTGRES_DB=${DASH_DB_NAME:-dashboard}
+        env_file:
+            - .env.db
         volumes:
             - dashboard-db-data:/var/lib/postgresql/data
         networks:
@@ -69,23 +67,8 @@ services:
             - dashboard_db
         secrets:
             - postgres_password_secret
-        environment:
-            - 'ALLOWED_HOSTS=["backend", "localhost"]'
-            - DB_DEFAULT_PASSWORD_FILE=/run/secrets/postgres_password_secret
-            - DB_DEFAULT_HOST=cloudsql-proxy
-            - DB_DEFAULT_USER=${DB_DEFAULT_USER:-kernelci}
-            - DB_DEFAULT_NAME=${DB_DEFAULT_NAME:-kcidb}
-            - DJANGO_SECRET_KEY=${DJANGO_SECRET_KEY}
-            - DEBUG=${DEBUG:-False}
-            - DISCORD_WEBHOOK_URL=${DISCORD_WEBHOOK_URL}
-            - REDIS_HOST=redis
-            - GMAIL_API_TOKEN=gmail_api_token.json
-            - DASH_DB_NAME=${DASH_DB_NAME:-dashboard}
-            - DASH_DB_USER=${DASH_DB_USER:-admin}
-            - DASH_DB_PASSWORD=${DASH_DB_PASSWORD:-admin}
-            - DASH_DB_HOST=dashboard_db
-            - DASH_DB_PORT=${DASH_DB_PORT:-5432}
-            - USE_DASHBOARD_DB=${USE_DASHBOARD_DB:-False}
+        env_file:
+            - .env.backend
 
     dashboard:
         build:
@@ -110,5 +93,5 @@ services:
               published: 80
               protocol: tcp
               mode: host
-        environment:
-            - PROXY_TARGET=http://backend:8000
+        env_file:
+            - .env.proxy