Read-only file system: '/srv/media/house_preview/question_4.PNG' - django

Question

I have a simple Django app deployed to App Engine, which connects to Cloud SQL (PostgreSQL) instance. This Django app allows users to login/register and put up items for sale. Login/register works fine, but when putting up items for sale I get the following error:
Request Method: POST
Django Version: 3.0.3
Python Version: 3.7.7
Installed Applications:
['projects',
'blog',
'users.apps.UsersConfig',
'crispy_forms',
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware']
Traceback (most recent call last):
File "/env/lib/python3.7/site-packages/django/core/handlers/exception.py", line 34, in inner
response = get_response(request)
File "/env/lib/python3.7/site-packages/django/core/handlers/base.py", line 115, in _get_response
response = self.process_exception_by_middleware(e, request)
File "/env/lib/python3.7/site-packages/django/core/handlers/base.py", line 113, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/env/lib/python3.7/site-packages/django/contrib/auth/decorators.py", line 21, in _wrapped_view
return view_func(request, *args, **kwargs)
File "/srv/projects/views.py", line 28, in createListing
link.save()
File "/srv/projects/models.py", line 24, in save
super(Listing_Database, self).save(*args, **kwargs)
File "/env/lib/python3.7/site-packages/django/db/models/base.py", line 746, in save
force_update=force_update, update_fields=update_fields)
File "/env/lib/python3.7/site-packages/django/db/models/base.py", line 784, in save_base
force_update, using, update_fields,
File "/env/lib/python3.7/site-packages/django/db/models/base.py", line 887, in _save_table
results = self._do_insert(cls._base_manager, using, fields, returning_fields, raw)
File "/env/lib/python3.7/site-packages/django/db/models/base.py", line 926, in _do_insert
using=using, raw=raw,
File "/env/lib/python3.7/site-packages/django/db/models/manager.py", line 82, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/env/lib/python3.7/site-packages/django/db/models/query.py", line 1204, in _insert
return query.get_compiler(using=using).execute_sql(returning_fields)
File "/env/lib/python3.7/site-packages/django/db/models/sql/compiler.py", line 1383, in execute_sql
for sql, params in self.as_sql():
File "/env/lib/python3.7/site-packages/django/db/models/sql/compiler.py", line 1328, in as_sql
for obj in self.query.objs
File "/env/lib/python3.7/site-packages/django/db/models/sql/compiler.py", line 1328, in <listcomp>
for obj in self.query.objs
File "/env/lib/python3.7/site-packages/django/db/models/sql/compiler.py", line 1327, in <listcomp>
[self.prepare_value(field, self.pre_save_val(field, obj)) for field in fields]
File "/env/lib/python3.7/site-packages/django/db/models/sql/compiler.py", line 1278, in pre_save_val
return field.pre_save(obj, add=True)
File "/env/lib/python3.7/site-packages/django/db/models/fields/files.py", line 288, in pre_save
file.save(file.name, file.file, save=False)
File "/env/lib/python3.7/site-packages/django/db/models/fields/files.py", line 87, in save
self.name = self.storage.save(name, content, max_length=self.field.max_length)
File "/env/lib/python3.7/site-packages/django/core/files/storage.py", line 52, in save
return self._save(name, content)
File "/env/lib/python3.7/site-packages/django/core/files/storage.py", line 267, in _save
fd = os.open(full_path, self.OS_OPEN_FLAGS, 0o666)
Exception Type: OSError at /projects/createListing
Exception Value: [Errno 30] Read-only file system: '/srv/media/house_preview/question_4.PNG'
I'm pretty sure it's something to do with image upload.

Answer 1

Writing to Google App Engine instance is not allowed,
you should use Google Cloud Storage if you want everything in Google realm
Edit your code to support different Google cloud storage backend -> for example using django-storage

Answer 2

It not possible to write files in the Google App Engine Standard Python3 environment except in the /tmp directory. As stated in the Python3 GAE official documentation:
The runtime includes a full filesystem. The filesystem is read-only except for the location /tmp, which is a virtual disk storing data in your App Engine instance's RAM.