add support for an .env file

.env-example

@@ -0,0 +1,5 @@
+POSTGRES_DB=network_inventory
+POSTGRES_PASSWORD=password
+DJANGO_SETTINGS_MODULE=network_inventory.settings.docker
+DJANGO_DEBUG=True
+DJANGO_SECRET_KEY=foo

.travis.yml

@@ -5,6 +5,7 @@ services:
 
 before_install:
 - docker-compose build
+- cp .env-example .env
 
 script:
 - make test

docker-compose.yml

@@ -7,8 +7,8 @@ services:
   db:
     image: postgres
     environment:
-      - POSTGRES_DB=network_inventory
-      - POSTGRES_PASSWORD=password
+      - "POSTGRES_DB=${POSTGRES_DB}"
+      - "POSTGRES_PASSWORD=${POSTGRES_PASSWORD}"
     volumes:
       - db_data:/var/lib/postgresql/data/
 
@@ -20,8 +20,8 @@ services:
     ports:
       - 8000:8000
     environment:
-      - DJANGO_SETTINGS_MODULE=network_inventory.settings.docker
-      - DJANGO_DEBUG=True
-      - DJANGO_SECRET_KEY=foo
+      - "DJANGO_SETTINGS_MODULE=${DJANGO_SETTINGS_MODULE}"
+      - "DJANGO_DEBUG=${DJANGO_DEBUG}"
+      - "DJANGO_SECRET_KEY=${DJANGO_SECRET_KEY}"
     depends_on:
       - db