Django + Mongo + Docker getting pymongo.errors.ServerSelectionTimeoutError - django

Question

I've been struggling to get a simple app running using Django, Djongo, Mongo, and Docker Compose. My setup looks like this:
docker-compose.yml
services:
mongodb:
image: mongo:latest
restart: always
environment:
MONGO_INITDB_ROOT_USERNAME: root
MONGO_INITDB_ROOT_PASSWORD: mongoadmin
MONGO_INITDB_DATABASE: django_mongodb_docker
ports:
- 27017:27017
web:
build: ./src
restart: always
command: python src/manage.py runserver 0.0.0.0:8000
volumes:
- .:/code
ports:
- 8000:8000
links:
- mongodb
Dockerfile
FROM python:3
ENV PYTHONUNBUFFERED=1
RUN mkdir /code
COPY . /code/
WORKDIR /code
COPY requirements.txt /code/
RUN pip install -r requirements.txt
settings.py
DATABASES = {
'default': {
'ENGINE': 'djongo',
'HOST': 'mongodb',
'PORT': 27017,
'USER': 'root',
'PASSWORD': 'mongoadmin',
'AUTH_SOURCE': 'admin',
'AUTH_MECHANISM': 'SCRAM-SHA-1',
}
}
What is annoying is that I am able to use pymongo from my web container to connect to the container running mongo. That works as follows.
from pymongo import MongoClient
c = MongoClient(
'mongodb://mongodb:27017',
username='root',
password='mongoadmin',
authSource='admin',
authMechanism='SCRAM-SHA-1')
print(c.server_info())
The issue is that when I go to run migrations from within my web container I get the following error.
Traceback (most recent call last):
File "/code/src/manage.py", line 22, in <module>
main()
File "/code/src/manage.py", line 18, in main
execute_from_command_line(sys.argv)
File "/usr/local/lib/python3.9/site-packages/django/core/management/__init__.py", line 401, in execute_from_command_line
utility.execute()
File "/usr/local/lib/python3.9/site-packages/django/core/management/__init__.py", line 395, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/usr/local/lib/python3.9/site-packages/django/core/management/base.py", line 330, in run_from_argv
self.execute(*args, **cmd_options)
File "/usr/local/lib/python3.9/site-packages/django/core/management/base.py", line 371, in execute
output = self.handle(*args, **options)
File "/usr/local/lib/python3.9/site-packages/django/core/management/base.py", line 85, in wrapped
res = handle_func(*args, **kwargs)
File "/usr/local/lib/python3.9/site-packages/django/core/management/commands/migrate.py", line 92, in handle
executor = MigrationExecutor(connection, self.migration_progress_callback)
File "/usr/local/lib/python3.9/site-packages/django/db/migrations/executor.py", line 18, in __init__
self.loader = MigrationLoader(self.connection)
File "/usr/local/lib/python3.9/site-packages/django/db/migrations/loader.py", line 53, in __init__
self.build_graph()
File "/usr/local/lib/python3.9/site-packages/django/db/migrations/loader.py", line 216, in build_graph
self.applied_migrations = recorder.applied_migrations()
File "/usr/local/lib/python3.9/site-packages/django/db/migrations/recorder.py", line 77, in applied_migrations
if self.has_table():
File "/usr/local/lib/python3.9/site-packages/django/db/migrations/recorder.py", line 56, in has_table
tables = self.connection.introspection.table_names(cursor)
File "/usr/local/lib/python3.9/site-packages/django/db/backends/base/introspection.py", line 48, in table_names
return get_names(cursor)
File "/usr/local/lib/python3.9/site-packages/django/db/backends/base/introspection.py", line 43, in get_names
return sorted(ti.name for ti in self.get_table_list(cursor)
File "/usr/local/lib/python3.9/site-packages/djongo/introspection.py", line 47, in get_table_list
for c in cursor.db_conn.list_collection_names()
File "/usr/local/lib/python3.9/site-packages/pymongo/database.py", line 863, in list_collection_names
for result in self.list_collections(session=session, **kwargs)]
File "/usr/local/lib/python3.9/site-packages/pymongo/database.py", line 825, in list_collections
return self.__client._retryable_read(
File "/usr/local/lib/python3.9/site-packages/pymongo/mongo_client.py", line 1460, in _retryable_read
server = self._select_server(
File "/usr/local/lib/python3.9/site-packages/pymongo/mongo_client.py", line 1278, in _select_server
server = topology.select_server(server_selector)
File "/usr/local/lib/python3.9/site-packages/pymongo/topology.py", line 241, in select_server
return random.choice(self.select_servers(selector,
File "/usr/local/lib/python3.9/site-packages/pymongo/topology.py", line 199, in select_servers
server_descriptions = self._select_servers_loop(
File "/usr/local/lib/python3.9/site-packages/pymongo/topology.py", line 215, in _select_servers_loop
raise ServerSelectionTimeoutError(
pymongo.errors.ServerSelectionTimeoutError: localhost:27017: [Errno 111] Connection refused, Timeout: 30s, Topology Description: <TopologyDescription id: 5f9ecaa5bbdc0433baa13966, topology_type: Single, servers: [<ServerDescription ('localhost', 27017) server_type: Unknown, rtt: None, error=AutoReconnect('localhost:27017: [Errno 111] Connection refused')>]>
In addition, I've tried to create a Djongo model and save it to see if maybe the problem is specific to migrations (essentially just trying to make any connection to mongo using djongo).
models.py
from djongo import models
class Blog(models.Model):
name = models.CharField(max_length=100)
test.py
b = Blog(name='test')
b.save()
That returns the following error:
The above exception was the direct cause of the following exception:
web_1 |
web_1 | Traceback (most recent call last):
web_1 | File "/usr/local/lib/python3.9/site-packages/djongo/cursor.py", line 51, in execute
web_1 | self.result = Query(
web_1 | File "/usr/local/lib/python3.9/site-packages/djongo/sql2mongo/query.py", line 783, in __init__
web_1 | self._query = self.parse()
web_1 | File "/usr/local/lib/python3.9/site-packages/djongo/sql2mongo/query.py", line 884, in parse
web_1 | raise exe from e
web_1 | djongo.exceptions.SQLDecodeError:
web_1 |
web_1 | Keyword: None
web_1 | Sub SQL: None
web_1 | FAILED SQL: INSERT INTO "game_blog" ("name") VALUES (%(0)s)
web_1 | Params: ['test']
web_1 | Version: 1.3.3
web_1 |
web_1 | The above exception was the direct cause of the following exception:
web_1 |
web_1 | Traceback (most recent call last):
web_1 | File "/usr/local/lib/python3.9/site-packages/django/db/backends/utils.py", line 84, in _execute
web_1 | return self.cursor.execute(sql, params)
web_1 | File "/usr/local/lib/python3.9/site-packages/djongo/cursor.py", line 59, in execute
web_1 | raise db_exe from e
web_1 | djongo.database.DatabaseError
web_1 |
web_1 | The above exception was the direct cause of the following exception:
web_1 |
web_1 | Traceback (most recent call last):
web_1 | File "/usr/local/lib/python3.9/site-packages/django/core/handlers/exception.py", line 47, in inner
web_1 | response = get_response(request)
web_1 | File "/usr/local/lib/python3.9/site-packages/django/core/handlers/base.py", line 179, in _get_response
web_1 | response = wrapped_callback(request, *callback_args, **callback_kwargs)
web_1 | File "/usr/local/lib/python3.9/site-packages/django/views/generic/base.py", line 70, in view
web_1 | return self.dispatch(request, *args, **kwargs)
web_1 | File "/usr/local/lib/python3.9/site-packages/django/views/generic/base.py", line 98, in dispatch
web_1 | return handler(request, *args, **kwargs)
web_1 | File "/code/src/game/views.py", line 9, in get
web_1 | b.save(using='mongo')
web_1 | File "/usr/local/lib/python3.9/site-packages/django/db/models/base.py", line 753, in save
web_1 | self.save_base(using=using, force_insert=force_insert,
web_1 | File "/usr/local/lib/python3.9/site-packages/django/db/models/base.py", line 790, in save_base
web_1 | updated = self._save_table(
web_1 | File "/usr/local/lib/python3.9/site-packages/django/db/models/base.py", line 895, in _save_table
web_1 | results = self._do_insert(cls._base_manager, using, fields, returning_fields, raw)
web_1 | File "/usr/local/lib/python3.9/site-packages/django/db/models/base.py", line 933, in _do_insert
web_1 | return manager._insert(
web_1 | File "/usr/local/lib/python3.9/site-packages/django/db/models/manager.py", line 85, in manager_method
web_1 | return getattr(self.get_queryset(), name)(*args, **kwargs)
web_1 | File "/usr/local/lib/python3.9/site-packages/django/db/models/query.py", line 1254, in _insert
web_1 | return query.get_compiler(using=using).execute_sql(returning_fields)
web_1 | File "/usr/local/lib/python3.9/site-packages/django/db/models/sql/compiler.py", line 1397, in execute_sql
web_1 | cursor.execute(sql, params)
web_1 | File "/usr/local/lib/python3.9/site-packages/django/db/backends/utils.py", line 98, in execute
web_1 | return super().execute(sql, params)
web_1 | File "/usr/local/lib/python3.9/site-packages/django/db/backends/utils.py", line 66, in execute
web_1 | return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
web_1 | File "/usr/local/lib/python3.9/site-packages/django/db/backends/utils.py", line 75, in _execute_with_wrappers
web_1 | return executor(sql, params, many, context)
web_1 | File "/usr/local/lib/python3.9/site-packages/django/db/backends/utils.py", line 84, in _execute
web_1 | return self.cursor.execute(sql, params)
web_1 | File "/usr/local/lib/python3.9/site-packages/django/db/utils.py", line 90, in __exit__
web_1 | raise dj_exc_value.with_traceback(traceback) from exc_value
web_1 | File "/usr/local/lib/python3.9/site-packages/django/db/backends/utils.py", line 84, in _execute
web_1 | return self.cursor.execute(sql, params)
web_1 | File "/usr/local/lib/python3.9/site-packages/djongo/cursor.py", line 59, in execute
web_1 | raise db_exe from e
web_1 | django.db.utils.DatabaseError
Any help on this would be greatly appreciated.
I have tried editing my mongodb.conf like this already.

Answer 1

According to this document, the settings.py should have a CLIENT section which contains:
A set of key-value pairs that will be passed directly to MongoClient as kwargs while creating a new client connection.
So try setting your settings.py to:
DATABASE = {
'default': {
'ENGINE': 'djongo',
'NAME': 'your-database-name',
'CLIENT': {
'host': 'mongodb://mongodb:27017',
'username': 'root',
'password': 'mongoadmin',
'authSource': 'admin',
'authMechanism': 'SCRAM-SHA-1',
}
}
}