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Python psycopg2, NO postgresql etc service running on mashine... Where is the postgress driver? where is pg_hba.conf? (FATAL: no pg_hba.conf entry)

I am using -in Linux- python 3 and psycopg2 to connect to some postres databases:
import psycopg2 as pg
connection = None
try:
connection = pg.connect(
user = "username",
password = "...",
host = "host_ip",
port = "5432",
database = "db_name",
)
cursor = connection.cursor()
# Print PostgreSQL Connection properties
print ( connection.get_dsn_parameters(),"\n")
# Print PostgreSQL version
cursor.execute("SELECT version();")
record = cursor.fetchone()
print("You are connected to - ", record,"\n")
cursor.close()
connection.close()
print("PostgreSQL connection is closed")
except (Exception, pg.Error) as error :
print ("Error while connecting to PostgreSQL", error)
For one of the DBs this works, but for the other I am getting:
Error while connecting to PostgreSQL FATAL: no pg_hba.conf entry for host "XXX.XXX.XXX.XXX", user "YYYY", database "ZZZZ", SSL off
I have checked the web and stackoverflow, and there are a lot of similar questions,
e.g. Psycopg2 reporting pg_hba.conf error
However, I am not root on the machine where I used pip/anaconda, and there seems to be no
sql service or anything similar running:
$ sudo systemctl status postgres*
$ sudo systemctl status postgres
Unit postgres.service could not be found.
$ sudo systemctl status postgresql
Unit postgresql.service could not be found.
$ sudo systemctl status post*
So none of the answers seem to be relevant, because this question seems to be based on the
postgress service running, or on the existence of pg_hba.conf, either of which do not in my system. Though note that a sample is included in my envs/py3/share/ (where py3 the name of my environment):
$ locate pg_hba.conf
/home/nick/anaconda3/envs/py3/share/pg_hba.conf.sample
My question here aims to -apart to find a way to solve my immediate problem- understand what psycopg2 is / how it ends up using pg_hba.conf, seemingly used in a postgresql service that does not seem to exist in my system:
Does psycopg2 is/uses a driver? Why does it seem to include pg_hba.conf.sample and what is one supposed to do with it? where to place pg_hba.conf(???) it to make psycopg2 read it?
Notes / Info based on comments:
The DB is not locally hosted. It is running on a different server.
I am able to access that DB using DBeaver and my local Ubuntu python, but a container (same psycopg2 version is not), so I speculate it is not a DB server issue.
It seems pg_hba.conf is a file that should only be on the server? (If so, that actually is part of the answer I am looking for...)

Mongod.service not found => Pop from an empty deque => Authentication failed

The Problem
I'm getting started with MongoDB on Python, I have a Ubuntu machine in my local network and MongoDB is installed there. When I try to connect with database using Python from Mac it throughs me an error. I searched about it and found out there is a .service called mongod.service that needs to be started along with mongodb.service. But when I try to start the mongod.service the it says the .service doesn't even exist. I tried both with IP and mongodb url, nothing works.
Ubuntu Terminal
$ sudo service mongod start
$ Failed to start mongod.service: Unit mongod.service not found.
$ sudo systemctl start mongod
$ Failed to start mongod.service: Unit mongod.service not found.
DataBase Link (a)
mongodb://user:password#192.168.0.106/database
Python Script (a)
#!/usr/bin/env python3
from pymongo import MongoClient
client = MongoClient('mongodb://user:password#192.168.0.106/database')
db = client['database']
collection = db['collection']
json = dict(message='hello world', token=0)
collection.insert_one(json)
macOS Terminal (a)
pymongo.errors.ServerSelectionTimeoutError: 192.168.0.106:27017: [Errno 61] Connection refused, Timeout: 30s, Topology Description: <TopologyDescription id: 60e140982a43032aef0dd634, topology_type: Single, servers: [<ServerDescription ('192.168.0.106', 27017) server_type: Unknown, rtt: None, error=AutoReconnect('192.168.0.106:27017: [Errno 61] Connection refused')>]>
DataBase Link (b)
mongodb+srv://user:password#cluster0.h9fmz.mongodb.net/database?retryWrites=true&w=majority
Python Script (b)
#!/usr/bin/env python3
from pymongo import MongoClient
client = MongoClient('mongodb+srv://user:password#cluster0.h9fmz.mongodb.net/database?retryWrites=true&w=majority')
db = client['database']
collection = db['collection']
json = dict(message='hello world', token=0)
collection.insert_one(json)
macOS Terminal (b)
Traceback (most recent call last):
File "/usr/local/lib/python3.9/site-packages/pymongo/pool.py", line 1278, in _get_socket
sock_info = self.sockets.popleft()
IndexError: pop from an empty deque
During handling of the above exception, another exception occurred:
.....
.....
.....
pymongo.errors.OperationFailure: bad auth : Authentication failed., full error: {'ok': 0, 'errmsg': 'bad auth : Authentication failed.', 'code': 8000, 'codeName': 'AtlasError'}
Note That
I'm providing the correct username and password for the database.
I'm using a machine on my local network, which is not a live server.
I've also tried the following commands but they did not solve anything.
Ubuntu Terminal
$ mongod --auth --port 27017
$ mongod --port 27017
$ sudo rm /var/lib/mongodb/mongod.lock
$ sudo mongod --repair

For accessing mongodb from another machine in local network. You will need to check the following:
There is no firewall restriction in the server machine or client machine. In case there is a firewall, you will need to add rule exceptions to allow this port to be accessible. Both incoming and outgoing. (Ubuntu firewall)
You will have to add bindIp config to the mongodb config in server machine. Refer to docs here. You will need to add something like this:
net:
bindIp: 0.0.0.0
port: 27017
Make sure you are able to connect using this ip: 192.168.0.106(server in local network) from the server machine itself. This will make sure the server is listening in this ip.
$ Failed to start mongod.service: Unit mongod.service not found.
The solution for this error could be found here
The mongo atlas error might be due to the following reasons:
You will have to create an database user in order to connect to mongodb.
you can find it under the left panel -> Database access -> Add user
This will be because of a mismatch with username and password. In case you have any special characters in your password you will have to url encode them.

PyMongo - can't connect to localhost?

I have tried running the following:
import pymongo
from pymongo import MongoClient
client = MongoClient('mongodb://localhost:27017/')
db = client.test_database
collection = db.test_collection
collection.find_one()
but I get
ServerSelectionTimeoutError: localhost:27017: [Errno 111] Connection refused
Any suggestions on how to fix this? I am running this behind a corporate proxy, but have already set environment variables for that in .bashrc.
EDIT
If I run mongo from the terminal, I get
$ mongo
MongoDB shell version v4.0.13
connecting to: mongodb://127.0.0.1:27017/?gssapiServiceName=mongodb
2019-10-16T10:30:23.269+0100 E QUERY [js] Error: couldn't connect to server 127.0.0.1:27017, connection attempt failed: SocketException: Error connecting to 127.0.0.1:27017 :: caused by :: Connection refused :
connect#src/mongo/shell/mongo.js:344:17
#(connect):2:6
exception: connect failed

Its look like you didn't run any mongo instance on your machine
run the command mongod -f <config_file> and then test it again (this may needs a sudo permissions)

ServerSelectionTimeoutError: localhost:27017: [Errno 111] Connection refused [duplicate]

I am trying to run a simple connection to pymongo but it keeps returning that the connection was refused
Here is what I tried:
>>>from pymongo import Connection
>>>connection = Connection('localhost',27017)
here is what I get
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/local/lib/python2.7/dist-packages/pymongo-2.0.1_-py2.7-linux i686.egg/pymongo/connection.py", line 348, in __init__
self.__find_node()
File "/usr/local/lib/python2.7/dist-packages/pymongo-2.0.1_-py2.7-linux- i686.egg/pymongo/connection.py", line 627, in __find_node
raise AutoReconnect(', '.join(errors))
pymongo.errors.AutoReconnect: could not connect to localhost:27017: [Errno 111] Connection refused
How do I fix this?

Removing mongod.lock inside /var/lib/mongodb
sudo rm /var/lib/mongodb/mongod.lock
And then restarting the service should do it. For example, in my Ubuntu installation, restarting the server is something like this:
sudo service mongodb start

If you found this page because you use Docker and you face the connection problem,
try to use in your client initialization the docker container name of the mongodb instead of the localhost:27017 or 0.0.0.0:27017
Steps to fix:
write docker ps in console
find the name of container (it's in the last column of the command output called NAMES
MongoClient('mongodb://CONTAINER_NAME')
PROFIT.

Just try following commands in given order :
sudo rm /var/lib/mongodb/mongod.lock
sudo mongod --repair
sudo service mongodb start
sudo service mongodb status
That's it now you could see following as output of last command:
mongodb start/running, process 2796

For anyone who's having this problem on a remote server rather than the localhost, try enabling external interfaces:
Go to the configuration file (ex. /etc/mongodb.conf)
Find bind_ip=127.0.0.1
Comment out that line with a # at the front
Restart mongod

It looks like you might not be running the MongoDB server. One thing that frequently trips me up is that if the server was shut down uncleanly, it will refuse to start up again until you remove the mongod.lock file from the data directory.

Try following commands :
sudo service mongod start
sudo service mongod status
db.py
import pymongo
from pymongo import MongoClient
#mongo client is connected
client = MongoClient()
db = client['db']

Rather than deleting mongod.lock, I'd recommend running 'mongod --repair'. (I figure it's better to go in through the front door whenever possible. And there may be other things that this catches as well, AFAIK.)

None of the above answers worked for me, as I am using docker-compose so this worked for me:
docker run --rm --volumes-from my-mongo-server mongo unlink "/data/db/mongod.lock"
docker run --rm --volumes-from my-mongo-server mongo --repair
Replace my-mongo-server with your container name/id.

If you're trying to connect from a server (other than your localhost), try checking if your mongo installation is complete :
you should have:
* /var/lib/mongodb file
* /var/log/mongodb file
* mongodb.service as service ( check by starting the service sudo service mongodb start )
If any of those fails, try reinstalling mongo ( Failed to start mongod.service: Unit mongod.service not found )
This solved my problem.
Cheers

For the newer versions(4.x) of MongoDb, you can try:
sudo rm /var/lib/mongodb/mongod.lock
sudo systemctl daemon-reload
sudo systemctl start mongod

First make sure you have installed mongodb using sudo apt install mongodb

Thanks, but for me i just had to stop mongod and then restart it and it worked fine without having to remove anything. PS : pymongo 2.7.2

mongodb refusing connection in python

I am using windows8, for writing code I use IDLE. I tried to connect python to mongodb. But when trying to get collection name than it gives an error.
ServerSelectionTimeoutError: localhost:20101: [Errno 10061] No connection could be made because the target machine actively refused it
This is code for which i am getting an error.
from pymongo import MongoClient
connection = MongoClient('localhost',20101)
db = connection['Bhautik']
collection = db['Student']
db.collection_names(include_system_collections=True)

By the output message you probably didn't set your mongo bind_ip or didn't set the dbpath. Try this:
mongod --dbpath <database_path> --bind_ip 127.0.0.1 --port 20101
It would be more helpful to put alongside with your code some information regarding the mongodb configuration, like the server port, if you are using authentication or not, which dbpath you are using and so on.
So put in your question your mongodb.conf (if you are using one) or the command you are using to start the mongo server.

If you are starting to use mongoDB after installation, make C:/data/db because it is a default database directory which mongoDB uses.
To change the database directory, do type below:
C:\Program Files\MongoDB\Server\3.x\bin> mongod --dbpath "c:\custom_folder"

You can try
run mongo like that:
"C:\\Program Files\\MongoDB\\Server\\3.6\\bin\\mongod.exe" --dbpath E:\\data\\db --port 27017 --bind_ip 127.0.0.1
E:\data\db should be your location path
then in you code
it will lok like
client = MongoClient("127.0.0.1", 27017)
db = client['addsome']
datas = db.follow_up
and if you want to access from a distant machine make sure you open the port "27017" in the firewall

Some times it's gives this error when you forgot to run the local server (if it's run with local server).
To run it you need to write on your terminal:
mongod
or, if MongoDB not in PATH, you can find it via this link in your computer:
C:\Program Files\MongoDB\Server\4.0\bin\mongod.exe

In order to run MongoDB,
You should have installed MongoDB into your OS, download it from https://www.mongodb.com/download-center/community?tck=docs_server
Add the installation's bin folder to your system environment variables.
Openup the terminal and check 'mongod' and 'mongo' commands are working.
Then try to rerun your python script.