docker: separate build instructions for demo compose file

docker/web-demo.yml

@@ -3,7 +3,6 @@ services:
 
   prosody:
     image: libervia/prosody:demo
-    build: prosody-demo
     depends_on:
       # we need to depend on backend to get IP address of the container for conf
       - backend
@@ -22,7 +21,6 @@ services:
     tmpfs: /var/lib/postgresql/data
 
   pubsub:
-    build: pubsub
     image: libervia/pubsub
     depends_on:
       - db
@@ -37,7 +35,6 @@ services:
 
   backend:
     image: libervia/backend:dev-demo
-    build: backend-dev-demo
     volumes:
       - libervia-web-demo_data:/home/libervia/.local/share/libervia
     ports:
@@ -50,7 +47,6 @@ services:
 
   web:
     image: libervia/web:dev-demo
-    build: libervia-web-dev-demo
     depends_on:
       - backend
     environment:

docker/web-demo_build.yml

@@ -0,0 +1,14 @@
+version: "3.6"
+services:
+
+  prosody:
+    image: libervia/prosody:demo
+    build: prosody-demo
+
+  backend:
+    image: libervia/backend:dev-demo
+    build: backend-dev-demo
+
+  web:
+    image: libervia/web:dev-demo
+    build: libervia-web-dev-demo