change heroku db handling

Dockerfile

@@ -4,8 +4,8 @@ WORKDIR /app
 
 COPY . .
 
-ARG HEROKU
-ENV HEROKU=$HEROKU
+ARG HEROKU_DB
+ENV HEROKU_DB=$HEROKU_DB
 ENV BOT_TOKEN=
 ENV SPOTIFY_ID=
 ENV SPOTIFY_SECRET=

config/config.py

@@ -43,12 +43,7 @@
 # Must be async-compatible
 # CHANGE ONLY IF YOU KNOW WHAT YOU'RE DOING
 DATABASE = alchemize_url(
-    get_env_var(
-        "DATABASE_URL",
-        "sqlite:///settings.db" if not os.getenv("HEROKU")
-        # assume postgres as default db on Heroku
-        else "postgres",
-    )
+    get_env_var("DATABASE_URL", os.getenv("HEROKU_DB") or "sqlite:///settings.db")
 )
 
 

heroku.yml

@@ -2,4 +2,5 @@ build:
   docker:
     worker: Dockerfile
   config:
-    HEROKU: 1
+    # your database type
+    HEROKU_DB: postgres