Can't connect DataStax AstraDB with Django app on Google Cloud - django

Question

I am trying to connect AstraDB with my application served by gcloud AppEngine. I am using Django and therefore have used django_cassandra_engine. I want to keep Postgres as my default DB and use cassandra as a second DB.
Everything works as expected on localhost,but when I deploy to gcloud, I receive 502 Bad gateway error and in the logs it says:
cassandra.cqlengine.CQLEngineException: Connection name 'cassandra'
doesn't exist in the registry.
I am using:
Django==4.1
django-cassandra-engine==1.7.0
cassandra-driver==3.25.0
My secure_connect_bundle (ZIP file) is in the same folder where manage.py is located.
This is my settings.py:
# [START db_setup]
# [START gaestd_py_django_database_config]
# Use django-environ to parse the connection string
DATABASES = {
"default": env.db(),
'cassandra': {
'ENGINE': 'django_cassandra_engine',
'NAME': 'the_keyspace',
'TEST_NAME': 'test_db',
'OPTIONS': {
'connection': {
'auth_provider': PlainTextAuthProvider(username=env("ASTRA_CLIENT_ID"),password=env("ASTRA_SECRET")),
'cloud': {
'secure_connect_bundle': os.path.join(BASE_DIR, "secure-connect-db.zip")
}
}
}
}
}
# If the flag as been set, configure to use proxy
if os.getenv("USE_CLOUD_SQL_AUTH_PROXY", None):
DATABASES["default"]["HOST"] = "127.0.0.1"
DATABASES["default"]["PORT"] = 5432
# [END gaestd_py_django_database_config]
# [END db_setup]
# Use a in-memory sqlite3 database when testing in CI systems
# TODO(glasnt) CHECK IF THIS IS REQUIRED because we're setting a val above
if os.getenv("TRAMPOLINE_CI", None):
DATABASES = {
"default": {
"ENGINE": "django.db.backends.sqlite3",
"NAME": os.path.join(BASE_DIR, "db.sqlite3"),
}
}

Answer 1

Just a thought, but I don't think you need the extra cassandra group in the DATABASES section. Try this:
DATABASES = {
"default": {
'ENGINE': 'django_cassandra_engine',
'NAME': 'brondau_keyspace',
We (DataStax) actually ran a workshop showing Django and Astra DB in December: https://www.youtube.com/watch?v=tUF_dX0lgt0
The Git repo can be found here: Build A Blog in Python with Django and Astra DB NoSQL Database
This section of the repo should help with your current issue: https://github.com/tomitokko/django-blog-with-astradb/blob/ddc1c2d608e8fc0d6569796775cdfaf503afab94/techblog/settings.py#L92
Anyway, give my suggestion a try and check the video and/or repo for additional help.

Answer 2

So the problem was that secure_connect_bundle (ZIP file) couldn't be extracted on AppEngine.
Setting 'use_default_tempdir' to True in cloud_config solves the issue.
If you are using python driver to establish connection, it should look like this:
cloud_config= {
'secure_connect_bundle': ASTRADB_CONNECT_BUNDLE,
'use_default_tempdir': True
}
Or if you use django_cassandra_engine:
'OPTIONS': {
'connection': {
'auth_provider': PlainTextAuthProvider(username=env("ASTRA_CLIENT_ID"),password=env("ASTRA_SECRET")),
'cloud': {
'secure_connect_bundle': 'secure-brondau-db.zip',
'use_default_tempdir': True
}
}
}