Use more volumes in docker-compose file

Also mount source directories as read-only (just in case)

Author: anthonynguyen

.gitignore

@@ -19,3 +19,4 @@ npm-debug.log
 yarn-error.log
 testem.log
 .env
+docker-compose.override.yml

docker-compose.yml

@@ -28,9 +28,11 @@ services:
     volumes:
       # Mount the src/ directory so we don't have to rebuild the Docker image
       # when we want to change some code
-      - ./src:/app/src
+      - ./src:/app/src:ro
+
       - index:/app/tmp
-      - cargo-cache:/app/target
+      - cargo-cache:/usr/local/cargo/registry
+      - target-cache:/app/target
   frontend:
     build:
       context: .
@@ -42,9 +44,10 @@ services:
       - 4200:4200
     volumes:
       # Mount the app/ directory so live reload works
-      - ./app:/app/app
+      - ./app:/app/app:ro
 
 volumes:
   postgres-data:
   cargo-cache:
+  target-cache:
   index: