Using SQLAlchemy on App Engine development server - python

I have seen some questions about using SQLAlchemy on App Engine to connect to Google Cloud SQL. But I'm not sure if it is possible to develop using a local MySQL database and the existing SQLAlchemy dialect. On my first attempt, I added SQLAlchemy 0.8.0 to the app and defined a schema:
from sqlalchemy import create_engine, Column, Integer, Table
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
foo_table = Table('foo', Base.metadata,
Column('id', Integer, primary_key=True, autoincrement=True),
)
And when I tried to create the tables on the development server using:
url = 'mysql+gaerdbms:///%s?instance=%s' % ('database_name', 'instance_name')
engine = create_engine(url)
Base.metadata.create_all(engine)
...I got an error DBAPIError: (ImportError) No module named pwd None None, which means that SQLAlchemy is importing a module that is blacklisted by the development server.
Am I doing something wrong? Or, if not, what should I do to use SQLAlchemy on the development server? Or maybe the first question is: Can I use the SQLAlchemy's gaerdbms dialect to develop in a local MySql database using the dev server?
Edit: this error doesn't happen only when trying to create tables. I created the tables manually and tried to query them, and the same error occurs.
The full traceback is:
Traceback (most recent call last):
File "[...]/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 1535, in __call__
rv = self.handle_exception(request, response, e)
File "[...]/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 1529, in __call__
rv = self.router.dispatch(request, response)
File "[...]/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 1278, in default_dispatcher
return route.handler_adapter(request, response)
File "[...]/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 1102, in __call__
return handler.dispatch()
File "[...]/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 572, in dispatch
return self.handle_exception(e, self.app.debug)
File "[...]/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 570, in dispatch
return method(*args, **kwargs)
File "[...]/webapp/admin.py", line 12, in get
db.Base.metadata.create_all(engine)
File "[...]/webapp/sqlalchemy/schema.py", line 2784, in create_all
tables=tables)
File "[...]/webapp/sqlalchemy/engine/base.py", line 1486, in _run_visitor
with self._optional_conn_ctx_manager(connection) as conn:
File "/usr/lib/python2.7/contextlib.py", line 17, in __enter__
return self.gen.next()
File "[...]/webapp/sqlalchemy/engine/base.py", line 1479, in _optional_conn_ctx_manager
with self.contextual_connect() as conn:
File "[...]/webapp/sqlalchemy/engine/base.py", line 1669, in contextual_connect
self.pool.connect(),
File "[...]/webapp/sqlalchemy/pool.py", line 272, in connect
return _ConnectionFairy(self).checkout()
File "[...]/webapp/sqlalchemy/pool.py", line 425, in __init__
rec = self._connection_record = pool._do_get()
File "[...]/webapp/sqlalchemy/pool.py", line 855, in _do_get
return self._create_connection()
File "[...]/webapp/sqlalchemy/pool.py", line 225, in _create_connection
return _ConnectionRecord(self)
File "[...]/webapp/sqlalchemy/pool.py", line 318, in __init__
self.connection = self.__connect()
File "[...]/webapp/sqlalchemy/pool.py", line 368, in __connect
connection = self.__pool._creator()
File "[...]/webapp/sqlalchemy/engine/strategies.py", line 80, in connect
return dialect.connect(*cargs, **cparams)
File "[...]/webapp/sqlalchemy/engine/default.py", line 279, in connect
return self.dbapi.connect(*cargs, **cparams)
File "[...]/google_appengine/google/storage/speckle/python/api/rdbms_googleapi.py", line 183, in __init__
super(GoogleApiConnection, self).__init__(*args, **kwargs)
File "[...]/google_appengine/google/storage/speckle/python/api/rdbms.py", line 810, in __init__
self.OpenConnection()
File "[...]/google_appengine/google/storage/speckle/python/api/rdbms.py", line 832, in OpenConnection
self.SetupClient()
File "[...]/google_appengine/google/storage/speckle/python/api/rdbms_googleapi.py", line 193, in SetupClient
self._client = RdbmsGoogleApiClient(**kwargs)
File "[...]/google_appengine/google/storage/speckle/python/api/rdbms_googleapi.py", line 106, in __init__
rdbms.OAUTH_CREDENTIALS_PATH)
File "/usr/lib/python2.7/posixpath.py", line 259, in expanduser
import pwd
File "[...]/google_appengine/google/appengine/tools/devappserver2/python/sandbox.py", line 822, in load_module
raise ImportError('No module named %s' % fullname)
DBAPIError: (ImportError) No module named pwd None None

I found a workaround. As it is, SQLAlchemy's gaerdbms dialect can't connect to a local database. But with the dialect below it can. Folow the instructions from this answer but use this dialect instead:
# mysql/gaerdbms.py
# Copyright (C) 2005-2013 the SQLAlchemy authors and contributors <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""
.. dialect:: mysql+gaerdbms
:name: Google Cloud SQL
:dbapi: rdbms
:connectstring: mysql+gaerdbms:///<dbname>?instance=<instancename>
:url: https://developers.google.com/appengine/docs/python/cloud-sql/developers-guide
This dialect is based primarily on the :mod:`.mysql.mysqldb` dialect with minimal
changes.
.. versionadded:: 0.7.8
Pooling
-------
Google App Engine connections appear to be randomly recycled,
so the dialect does not pool connections. The :class:`.NullPool`
implementation is installed within the :class:`.Engine` by
default.
"""
import os
import re
from sqlalchemy.dialects.mysql.mysqldb import MySQLDialect_mysqldb
from sqlalchemy.pool import NullPool
class MySQLDialect_gaerdbms(MySQLDialect_mysqldb):
#classmethod
def dbapi(cls):
# from django:
# http://code.google.com/p/googleappengine/source/
# browse/trunk/python/google/storage/speckle/
# python/django/backend/base.py#118
# see also [ticket:2649]
# see also https://stackoverflow.com/q/14224679/34549
if is_production():
# Production mode.
from google.storage.speckle.python.api import rdbms_apiproxy
return rdbms_apiproxy
elif is_remote_mode():
# Development mode with remote database.
from google.storage.speckle.python.api import rdbms_googleapi
return rdbms_googleapi
else:
# Development mode with local database.
from google.appengine.api import rdbms_mysqldb
return rdbms_mysqldb
#classmethod
def get_pool_class(cls, url):
# Cloud SQL connections die at any moment
return NullPool
def create_connect_args(self, url):
opts = url.translate_connect_args()
if is_production() or is_remote_mode():
# 'dsn' and 'instance' are because we are skipping
# the traditional google.api.rdbms wrapper.
# they are not needed in local mode; 'dns' even causes an error.
opts['dsn'] = ''
opts['instance'] = url.query['instance']
return [], opts
def _extract_error_code(self, exception):
match = re.compile(r"^(\d+):|^\((\d+),").match(str(exception))
# The rdbms api will wrap then re-raise some types of errors
# making this regex return no matches.
code = match.group(1) or match.group(2) if match else None
if code:
return int(code)
dialect = MySQLDialect_gaerdbms
def is_production():
return os.getenv('SERVER_SOFTWARE', '').startswith('Google App Engine')
def is_remote_mode():
return os.getenv('SETTINGS_MODE') == 'prod'
This dialect uses a local database by default when running on the development server. To use remote access to Google Cloud SQL during development, a variable must be set in the environment, following the pattern used by Django:
os.environ['SETTINGS_MODE'] = 'prod'

Related

Why am I getting pymongo.errors.AutoReconnect: connection pool paused

I'm getting this error of autoreconnect, and there are around 100 connections in the logs during this call to .objects. Here is the document:
class NotificationDoc(Document):
patient_id = StringField(max_length=32)
type = StringField(max_length=32)
sms_sent = BooleanField(default=False)
email_sent = BooleanField(default=False)
sending_time = DateTimeField(default=datetime.utcnow)
def __unicode__(self):
return "{}_{}_{}".format(self.patient_id, self.type, self.sending_time.strftime('%Y-%m-%d'))
and this is the query call that causes the issue:
docs = NotificationDoc.objects(sending_time__lte=from_date)
This is the complete stacktrace. How can I understand what is going on?
pymongo.errors.AutoReconnect: connection pool paused
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "/usr/local/lib/python3.8/site-packages/celery/app/trace.py", line 451, in trace_task
R = retval = fun(*args, **kwargs)
File "/usr/local/lib/python3.8/site-packages/celery/app/trace.py", line 734, in __protected_call__
return self.run(*args, **kwargs)
File "/app/src/reminder/configurations/app/worker.py", line 106, in schedule_recall
schedule_recall_use_case.execute()
File "/app/src/reminder/domain/notification/recall/use_cases/schedule_recall.py", line 24, in execute
notifications_sent = self.notifications_provider.find_recalled_notifications_for_date(no_recalls_before_date)
File "/app/src/reminder/data_providers/database/odm/repositories.py", line 42, in find_recalled_notifications_for_date
if NotificationDoc.objects(sending_time__lte=from_date).count() > 0:
File "/usr/local/lib/python3.8/site-packages/mongoengine/queryset/queryset.py", line 144, in count
return super().count(with_limit_and_skip)
File "/usr/local/lib/python3.8/site-packages/mongoengine/queryset/base.py", line 423, in count
count = count_documents(
File "/usr/local/lib/python3.8/site-packages/mongoengine/pymongo_support.py", line 38, in count_documents
return collection.count_documents(filter=filter, **kwargs)
File "/usr/local/lib/python3.8/site-packages/pymongo/collection.py", line 1502, in count_documents
return self.__database.client._retryable_read(
File "/usr/local/lib/python3.8/site-packages/pymongo/mongo_client.py", line 1307, in _retryable_read
with self._secondaryok_for_server(read_pref, server, session) as (
File "/usr/local/lib/python3.8/contextlib.py", line 113, in __enter__
return next(self.gen)
File "/usr/local/lib/python3.8/site-packages/pymongo/mongo_client.py", line 1162, in _secondaryok_for_server
with self._get_socket(server, session) as sock_info:
File "/usr/local/lib/python3.8/contextlib.py", line 113, in __enter__
return next(self.gen)
File "/usr/local/lib/python3.8/site-packages/pymongo/mongo_client.py", line 1099, in _get_socket
with server.get_socket(
File "/usr/local/lib/python3.8/contextlib.py", line 113, in __enter__
return next(self.gen)
File "/usr/local/lib/python3.8/site-packages/pymongo/pool.py", line 1371, in get_socket
sock_info = self._get_socket(all_credentials)
File "/usr/local/lib/python3.8/site-packages/pymongo/pool.py", line 1436, in _get_socket
self._raise_if_not_ready(emit_event=True)
File "/usr/local/lib/python3.8/site-packages/pymongo/pool.py", line 1407, in _raise_if_not_ready
_raise_connection_failure(
File "/usr/local/lib/python3.8/site-packages/pymongo/pool.py", line 250, in _raise_connection_failure
raise AutoReconnect(msg) from error
pymongo.errors.AutoReconnect: mongo:27017: connection pool paused
turned out to be celery is leaving connections open, so here is the solution
from mongoengine import disconnect
from celery.signals import task_prerun
#task_prerun.connect
def on_task_init(*args, **kwargs):
disconnect(alias='default')
connect(db, host=host, port=port, maxPoolSize=400, minPoolSize=200, alias='default')
This could be related to the fact that PyMongo is not fork-safe. If you're using a process pool in any way, which includes server software like uWSGI and even some configurations of popular ASGI servers.
Every time you run a query in PyMongo, that MongoClient object becomes fork-unsafe. A MongoClient object that has never run any queries is fork-safe. Created Database and Collection objects will reference back to their parent MongoClient without checking for existence.
I do see you are using MongoEngine, which uses PyMongo underneath. I don't know the semantics of that particular library but I would assume they are the same.
In short: you must re-create your connections as part of your forking process.
pip install -U pymongo; is already fix; see this https://github.com/mongodb/mongo-python-driver/pull/944

Random NoTransaction in Pyramid

I'm having trouble identifying the source of transaction.interfaces.NoTransaction errors within my Pyramid App. I don't see any patterns to when the error happens, so to me it's quite random.
This app is a (semi-) RESTful API and uses SQLAlchemy and MySQL. I'm currently running within a docker container that connects to an external (bare metal) MySQL instance on the same host OS.
Here's the stack trace for a login attempt within the App. This error happened right after another login attempt that was actually successful.
2020-06-15 03:57:18,982 DEBUG [txn.140501728405248:108][waitress-1] new transaction
2020-06-15 03:57:18,984 INFO [sqlalchemy.engine.base.Engine:730][waitress-1] BEGIN (implicit)
2020-06-15 03:57:18,984 DEBUG [txn.140501728405248:576][waitress-1] abort
2020-06-15 03:57:18,985 ERROR [waitress:357][waitress-1] Exception while serving /auth
Traceback (most recent call last):
File "/usr/local/lib/python3.8/site-packages/waitress/channel.py", line 350, in service
task.service()
File "/usr/local/lib/python3.8/site-packages/waitress/task.py", line 171, in service
self.execute()
File "/usr/local/lib/python3.8/site-packages/waitress/task.py", line 441, in execute
app_iter = self.channel.server.application(environ, start_response)
File "/usr/local/lib/python3.8/site-packages/pyramid/router.py", line 270, in __call__
response = self.execution_policy(environ, self)
File "/usr/local/lib/python3.8/site-packages/pyramid_retry/__init__.py", line 127, in retry_policy
response = router.invoke_request(request)
File "/usr/local/lib/python3.8/site-packages/pyramid/router.py", line 249, in invoke_request
response = handle_request(request)
File "/usr/local/lib/python3.8/site-packages/pyramid_tm/__init__.py", line 178, in tm_tween
reraise(*exc_info)
File "/usr/local/lib/python3.8/site-packages/pyramid_tm/compat.py", line 36, in reraise
raise value
File "/usr/local/lib/python3.8/site-packages/pyramid_tm/__init__.py", line 135, in tm_tween
userid = request.authenticated_userid
File "/usr/local/lib/python3.8/site-packages/pyramid/security.py", line 381, in authenticated_userid
return policy.authenticated_userid(self)
File "/opt/REDACTED-api/REDACTED_api/auth/policy.py", line 208, in authenticated_userid
result = self._authenticate(request)
File "/opt/REDACTED-api/REDACTED_api/auth/policy.py", line 199, in _authenticate
session = self._get_session_from_token(token)
File "/opt/REDACTED-api/REDACTED_api/auth/policy.py", line 320, in _get_session_from_token
session = service.get(session_id)
File "/opt/REDACTED-api/REDACTED_api/service/__init__.py", line 122, in get
entity = self.queryset.filter(self.Meta.model.id == entity_id).first()
File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/query.py", line 3375, in first
ret = list(self[0:1])
File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/query.py", line 3149, in __getitem__
return list(res)
File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/query.py", line 3481, in __iter__
return self._execute_and_instances(context)
File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/query.py", line 3502, in _execute_and_instances
conn = self._get_bind_args(
File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/query.py", line 3517, in _get_bind_args
return fn(
File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/query.py", line 3496, in _connection_from_session
conn = self.session.connection(**kw)
File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/session.py", line 1138, in connection
return self._connection_for_bind(
File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/session.py", line 1146, in _connection_for_bind
return self.transaction._connection_for_bind(
File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/session.py", line 458, in _connection_for_bind
self.session.dispatch.after_begin(self.session, self, conn)
File "/usr/local/lib/python3.8/site-packages/sqlalchemy/event/attr.py", line 322, in __call__
fn(*args, **kw)
File "/usr/local/lib/python3.8/site-packages/zope/sqlalchemy/datamanager.py", line 268, in after_begin
join_transaction(
File "/usr/local/lib/python3.8/site-packages/zope/sqlalchemy/datamanager.py", line 233, in join_transaction
DataManager(
File "/usr/local/lib/python3.8/site-packages/zope/sqlalchemy/datamanager.py", line 89, in __init__
transaction_manager.get().join(self)
File "/usr/local/lib/python3.8/site-packages/transaction/_manager.py", line 91, in get
raise NoTransaction()
transaction.interfaces.NoTransaction
The trace shows that the execution eventually reaches my project, but only my custom authentication policy. And it fails right where the database should be queried for the user.
What intrigues me here is the third line on the stack trace. It seems Waitress somehow aborted the transaction it created? Any clue why?
EDIT: Here's the code where that happens: policy.py:320
def _get_session_from_token(self, token) -> UserSession:
try:
session_id, session_secret = self.parse_token(token)
except InvalidToken as e:
raise SessionNotFound(e)
service = AuthService(self.dbsession, None)
try:
session = service.get(session_id) # <---- Service Class called here
except NoResultsFound:
raise SessionNotFound("Invalid session found Request headers. "
"Session id: %s".format(session_id))
if not service.check_session(session, session_secret):
raise SessionNotFound("Session signature does not match")
now = datetime.now(tz=pytz.UTC)
if session.validity < now:
raise SessionNotFound(
"Current session ID {session_id} is expired".format(
session_id=session.id
)
)
return session
And here is an a view on the that service class method:
class AuthService(ModelService):
class Meta:
model = UserSession
queryset = Query(UserSession)
search_fields = []
order_fields = [UserSession.created_at.desc()]
# These below are from the generic ModelClass father class
def __init__(self, dbsession: Session, user_id: str):
self.user_id = user_id
self.dbsession = dbsession
self.Meta.queryset = self.Meta.queryset.with_session(dbsession)
self.logger = logging.getLogger("REDACTED")
#property
def queryset(self):
return self.Meta.queryset
def get(self, entity_id) -> Base:
entity = self.queryset.filter(self.Meta.model.id == entity_id).first()
if not entity:
raise NoResultsFound(f"Could not find requested ID {entity_id}")
As you can see, the there's already some exception treatment. I really don't see what other exception I could try to catch on AuthService.get
I found the solution to be much simpler than tinkering inside Pyramid or SQLAlchemy.
Debugging my Authentication Policy closely, I found out that my it was keeping a sticky reference for the dbsession. It was stored on the first request ever who used it, and never released.
The first request works as expected, the following one fails: My understanding is that the object is still in memory while the app is running, and after the initial transaction is closed. The second request has a new connection, and a new transaction, but the object in memory still points to the previous one, that when used ultimately causes this.
What I don't understand is why the exception didn't happen sometimes. As I mentioned initially, it was seemingly random.
Another thing that I struggled with was in writing a test case to expose the issue. On my tests, the issue never happens because I have (and I've never seen it done differently) a single connection and a single transaction throughout the entire testing session, as opposed of a new connection/transaction per request, so I have not found no way to actually reproduce.
Please let me know if that makes sense, and if you can shed a light on how to expose the bug on a test case.

authendication failed when connecting to mongodb in mlab

I am trying to connect to my mongodb in mlab.com using flask but when I run my flask script I am getting Authentication failed error, please help.
my code:
from flask import Flask, jsonify, request
from flask_pymongo import PyMongo
app = Flask(__name__)
app.config['MONGO_DBNAME'] = 'mydb'
app.config['MONGO_URI'] = 'mongodb://user:pwd#ds157799.mlab.com:57799/mydb'
mongo = PyMongo(app)
#app.route('/framework', methods=['GET'])
def get_all_frameworks():
framework = mongo.db.framework
output = []
for q in framework.find():
output.append({'name' : q['name'], 'language' : q['language']})
return jsonify({'result' : output})
Error:
File "mongo.py", line 12, in <module>
mongo = PyMongo(app)
File "C:\Users\ELCOT\AppData\Local\Programs\Python\Python35\lib\site-packages\flask_pymongo\__init__.py", line 97, in __init__
self.init_app(app, config_prefix)
File "C:\Users\ELCOT\AppData\Local\Programs\Python\Python35\lib\site-packages\flask_pymongo\__init__.py", line 283, in init_app
mechanism=auth_mechanism)
File "C:\Users\ELCOT\AppData\Local\Programs\Python\Python35\lib\site-packages\pymongo\database.py", line 1167, in authenticate
connect=True)
File "C:\Users\ELCOT\AppData\Local\Programs\Python\Python35\lib\site-packages\pymongo\mongo_client.py", line 588, in _cache_credentials
sock_info.authenticate(credentials)
File "C:\Users\ELCOT\AppData\Local\Programs\Python\Python35\lib\site-packages\pymongo\pool.py", line 620, in authenticate
auth.authenticate(credentials, self)
File "C:\Users\ELCOT\AppData\Local\Programs\Python\Python35\lib\site-packages\pymongo\auth.py", line 486, in authenticate
auth_func(credentials, sock_info)
File "C:\Users\ELCOT\AppData\Local\Programs\Python\Python35\lib\site-packages\pymongo\auth.py", line 237, in _authenticate_scram_sha1
res = sock_info.command(source, cmd)
File "C:\Users\ELCOT\AppData\Local\Programs\Python\Python35\lib\site-packages\pymongo\pool.py", line 517, in command
collation=collation)
File "C:\Users\ELCOT\AppData\Local\Programs\Python\Python35\lib\site-packages\pymongo\network.py", line 125, in command
parse_write_concern_error=parse_write_concern_error)
File "C:\Users\ELCOT\AppData\Local\Programs\Python\Python35\lib\site-packages\pymongo\helpers.py", line 145, in _check_command_response
raise OperationFailure(msg % errmsg, code, response)
pymongo.errors.OperationFailure: Authentication failed.
Please help to resolve this.
You can use this as an alternative to sign in to your database. This is tested and works :
connection = pymongo.MongoClient(HOST, PORT)
db = connection[databasename]
db.authenticate(database_user, database_pass)
I created a new user with password for my db, and worked fine.
https://www.reddit.com/r/flask/comments/5ftqvm/how_to_use_pymongo_with_hosted_mongodb_mlab/
This Works fine. For me connecting via URI string from mLab database doesn't work as well.

Flask_MongoEngine doesn't work on Webfaction?

I'm currently trying to deploy a website built with the Python Flask framework to Webfaction. I've deployed a MongoDB to which I can succesfully connect from the MongoDB interactive interpreter:
[celli#web498 ~]$ mongo localhost:18209/admin
MongoDB shell version: 3.0.2
connecting to: localhost:18209/admin
> db.auth("awesomeusername", "anawesomepassword")
1
When starting the website, it can successfully connect using these credentials in my flask config.py file:
MONGODB_SETTINGS = {
'db': 'tc',
'port': 18209,
'username': 'awesomeusername',
'password': 'anawesomepassword',
}
But when I visit a page which does a query I get the error below. This code works perfectly well on another server, so the mistake lies somewhere in either the setup of my MongoDB instance, or in the connection to it. I also find it strange that setting up the connection works fine, but querying it creates this Authentication failed error.
Any idea how I can fix this? All tips are welcome!
File "/home/celli/webapps/tc/venv/lib/python2.7/site-packages/flask_login.py", line 758, in decorated_view
return func(*args, **kwargs)
File "/home/celli/webapps/tc/tc/app/views/webviews.py", line 220, in myTickets
userDocs = UserDocument.objects(id__in=[ticket.doc_id for ticket in userTickets])
File "/home/celli/webapps/tc/venv/lib/python2.7/site-packages/mongoengine/queryset/manager.py", line 37, in __get__
queryset = queryset_class(owner, owner._get_collection())
File "/home/celli/webapps/tc/venv/lib/python2.7/site-packages/mongoengine/document.py", line 168, in _get_collection
db = cls._get_db()
File "/home/celli/webapps/tc/venv/lib/python2.7/site-packages/mongoengine/document.py", line 162, in _get_db
return get_db(cls._meta.get("db_alias", DEFAULT_CONNECTION_NAME))
File "/home/celli/webapps/tc/venv/lib/python2.7/site-packages/mongoengine/connection.py", line 143, in get_db
source=conn_settings['authentication_source'])
File "/home/celli/webapps/tc/venv/lib/python2.7/site-packages/pymongo/database.py", line 978, in authenticate
self.connection._cache_credentials(self.name, credentials)
File "/home/celli/webapps/tc/venv/lib/python2.7/site-packages/pymongo/mongo_client.py", line 467, in _cache_credentials
auth.authenticate(credentials, sock_info, self.__simple_command)
File "/home/celli/webapps/tc/venv/lib/python2.7/site-packages/pymongo/auth.py", line 475, in authenticate
auth_func(credentials[1:], sock_info, cmd_func)
File "/home/celli/webapps/tc/venv/lib/python2.7/site-packages/pymongo/auth.py", line 450, in _authenticate_default
return _authenticate_scram_sha1(credentials, sock_info, cmd_func)
File "/home/celli/webapps/tc/venv/lib/python2.7/site-packages/pymongo/auth.py", line 238, in _authenticate_scram_sha1
sasl_start, sasl_continue)
File "/home/celli/webapps/tc/venv/lib/python2.7/site-packages/pymongo/auth.py", line 185, in _scram_sha1_conversation
res, _ = cmd_func(sock_info, source, sasl_start)
File "/home/celli/webapps/tc/venv/lib/python2.7/site-packages/pymongo/mongo_client.py", line 703, in __simple_command
helpers._check_command_response(response, None, msg)
File "/home/celli/webapps/tc/venv/lib/python2.7/site-packages/pymongo/helpers.py", line 182, in _check_command_response
raise OperationFailure(msg % errmsg, code, response)
OperationFailure: command SON([('saslStart', 1), ('mechanism', 'SCRAM-SHA-1'), ('autoAuthorize', 1), ('payload', Binary('n,,n=awesomeusername,r=NjAxNTEwMjc5MzAy', 0))]) on namespace tc.$cmd failed: Authentication failed.
MongoDB's users are per-database. In your example you show that you connect to the admin database, but the error message is simply telling you that your user is trying to authenticate with the tc database. Probably your user doesn't have a role on tc.
(The other possibility is that tc is not the database you want to connect to; you need to specify the correct database name in your connection params/string).

Catching python exception in its own class

I'm having a strange problem right now.
In my program I try to catch an exception inside a class, de class is used in a separate python file but the exception bubbles trough to the calling file.
How can I fix this?
Example:
main.py
#from sqlalchemy.exc import SQLAlchemyError, DatabaseError
from os import path
from helpers.db import DB
from models.group import Group
from models.entity import Entity
PROJECT_PATH = path.split(path.abspath(__file__))[0]
DATABASE_PATH = PROJECT_PATH + '/datastore/test.db'
class PasswordManager:
database = DB(DATABASE_PATH)
if __name__ == "__main__":
PasswordManager()
output
Traceback (most recent call last):
trying to build a SQLEngine
File "/home/tom/Projects/test/test/test.py", line 11, in <module>
class test:
File "/home/tom/Projects/test/test/test.py", line 23, in test
database = DB(DATABASE_PATH)
File "/home/tom/Projects/test/test/helpers/db.py", line 19, in __init__
self.buildDatabaseModels()
File "/home/tom/Projects/test/test/helpers/db.py", line 39, in buildDatabaseModels
Base.metadata.create_all(self.SQLEngine, checkfirst=True)
File "/home/tom/Projects/test/local/lib/python2.7/site-packages/sqlalchemy/sql/schema.py", line 3308, in create_all
tables=tables)
File "/home/tom/Projects/test/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1516, in _run_visitor
conn._run_visitor(visitorcallable, element, **kwargs)
File "/home/tom/Projects/test/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1164, in _run_visitor
**kwargs).traverse_single(element)
File "/home/tom/Projects/test/local/lib/python2.7/site-packages/sqlalchemy/sql/visitors.py", line 119, in traverse_single
return meth(obj, **kw)
File "/home/tom/Projects/test/local/lib/python2.7/site-packages/sqlalchemy/sql/ddl.py", line 696, in visit_metadata
if self._can_create_table(t)]
File "/home/tom/Projects/test/local/lib/python2.7/site-packages/sqlalchemy/sql/ddl.py", line 674, in _can_create_table
table.name, schema=table.schema)
File "/home/tom/Projects/test/local/lib/python2.7/site-packages/sqlalchemy/dialects/sqlite/base.py", line 781, in has_table
cursor = _pragma_cursor(connection.execute(statement))
File "/home/tom/Projects/test/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 709, in execute
return self._execute_text(object, multiparams, params)
File "/home/tom/Projects/test/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 858, in _execute_text
statement, parameters
File "/home/tom/Projects/test/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 927, in _execute_context
context)
File "/home/tom/Projects/test/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1076, in _handle_dbapi_exception
exc_info
File "/home/tom/Projects/test/local/lib/python2.7/site-packages/sqlalchemy/util/compat.py", line 185, in raise_from_cause
reraise(type(exception), exception, tb=exc_tb)
File "/home/tom/Projects/test/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 920, in _execute_context
context)
File "/home/tom/Projects/test/local/lib/python2.7/site-packages/sqlalchemy/engine/default.py", line 425, in do_execute
cursor.execute(statement, parameters)
sqlalchemy.exc.DatabaseError: (DatabaseError) file is encrypted or is not a database u'PRAGMA table_info("groups")' ()
DB.py
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
from sqlalchemy.exc import DatabaseError, SQLAlchemyError
from models import *
from helpers import Base
from helpers.crypt import Crypt
class DB:
SQLEngine = None
SessionMaker = None
Session = None
BuildEngineErrorCount = 0
def __init__(self, db_path):
self.buildEngine(db_path)
self.buildDatabaseModels()
def buildEngine(self, db_path):
try:
self.SQLEngine = create_engine('sqlite:////' + db_path)
print "trying to build a SQLEngine"
except BaseException, er:
print "Errors %s" % er
for error in er.args:
if error == '(DatabaseError) file is encrypted or is not a database':
self.BuildEngineErrorCount += 1
c = Crypt()
c.setKey('Test')
c.decryptDB(db_path)
if self.BuildEngineErrorCount < 5:
self.buildEngine(db_path)
def buildDatabaseModels(self):
if self.SQLEngine is None:
raise Exception("No SQLEngine found")
Base.metadata.create_all(self.SQLEngine, checkfirst=True)
def createSession(self):
if self.SessionMaker is not None or self.Session is not None:
raise Exception("Session already mapped")
self.SessionMaker = sessionmaker(bind=self.SQLEngine)
self.Session = self.SessionMaker()
return self.Session
As you can see I try to catch that exception in the db class, but it isn't catching anything.
Does anybody know what I do wrong?
Your exception is coming from a different method than the one you put the try-except in. Specifically, the exception comes from
Base.metadata.create_all(self.SQLEngine, checkfirst=True)
in buildDatabaseModels, but you have your try-except in buildEngine.

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