Fix "Read-only file system" errors

Close #392.

CHANGELOG.md

@@ -4,6 +4,8 @@ Note: Breaking changes between versions are indicated by "💥".
 
 ## Unreleased
 
+- [Bugfix] Fix "Read-only file system" errors when running `tutor dev runserver` commands on Mac OS.
+
 ## v11.0.3 (2020-12-15)
 
 - [Bugfix] Fix upload of video transcripts to S3 (again)

tutor/templates/build/openedx-dev/bin/docker-entrypoint.sh

@@ -2,9 +2,13 @@
 export DJANGO_SETTINGS_MODULE=$SERVICE_VARIANT.envs.$SETTINGS
 
 if id -u openedx > /dev/null 2>&1; then
-    # Change file permissions of mounted volumes
+    # Change owners of mounted volumes
     echo "Setting file permissions for user openedx..."
-    find /openedx -not -path "/openedx/edx-platform/*" -not -user openedx -exec chown openedx:openedx {} \+
+    find /openedx \
+        -not -path "/openedx/edx-platform/*" \
+        -not -user openedx \
+        -perm /u=w \
+        -exec chown openedx:openedx {} \+
     echo "File permissions set."
 
     # Run CMD as user openedx
@@ -13,4 +17,3 @@ else
     echo "Running openedx-dev as root user"
     exec "$@"
 fi
-