try this

.drone.yml

@@ -114,7 +114,7 @@ steps:
     - up -d
   volumes:
   - name: env
-    path: /.env
+    path: ./.env
 
 - name: Send Status Notifications
   image: plugins/webhook

Dockerfile

@@ -1,3 +1,5 @@
 FROM node
 WORKDIR /
+COPY . .
+RUN yarn build
 CMD ["node", "dist/lib/server/index.js"]