MongoDB test server on Oracle Linux

I use Oracle Enterprise Linux on VirtualBox running on my Windows 10 laptop for test servers (virtual machines) of various types of software. I just setup a MongoDB VM yesterday and thought I would document some of the things I did which are not in the standard documentation.

I followed this URL for the install:

https://docs.mongodb.com/manual/tutorial/install-mongodb-on-red-hat/

I created the yum repository file mongodb-org-4.4.repo as documented:

[root@mongodb yum.repos.d]# cat mongodb-org-4.4.repo
[mongodb-org-4.4]
name=MongoDB Repository
baseurl=https://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/4.4/x86_64/
gpgcheck=1
enabled=1
gpgkey=https://www.mongodb.org/static/pgp/server-4.4.asc

I installed the MongoDB yum package:

[root@mongodb yum.repos.d]# sudo yum install -y mongodb-org
Loaded plugins: langpacks, ulninfo
mongodb-org-4.4                                                                                                           | 2.5 kB  00:00:00
ol7_UEKR4                                                                                                                 | 2.5 kB  00:00:00
ol7_latest                                                                                                                | 2.7 kB  00:00:00
mongodb-org-4.4/7Server/primary_db                                                                                        |  47 kB  00:00:02
Resolving Dependencies
--> Running transaction check
---> Package mongodb-org.x86_64 0:4.4.6-1.el7 will be installed
--> Processing Dependency: mongodb-org-shell = 4.4.6 for package: mongodb-org-4.4.6-1.el7.x86_64
...

I didn’t need sudo since I was root, but it worked. I don’t know if this was really needed but I set ulimit with these commands:

ulimit -f unlimited
ulimit -t unlimited
ulimit -v unlimited
ulimit -l unlimited
ulimit -n 64000
ulimit -m unlimited
ulimit -u 64000

I am not sure if these commands stick when you run them as root. They seem to but for now I’ve been running them manually after I reboot. These were documented here:

https://docs.mongodb.com/manual/reference/ulimit/

Based on this document I also created the file /etc/security/limits.d/99-mongodb-nproc.conf:

[root@mongodb ~]# cat /etc/security/limits.d/99-mongodb-nproc.conf
*          soft    nproc     64000
*          hard    nproc     64000
root       soft    nproc     unlimited
[root@mongodb ~]#

I don’t know for sure if this was needed, but it did not cause any problems.

I edited /etc/selinux/config to prevent SELinux from interfering:

[root@mongodb selinux]# diff config.07012021 config
7c7
< SELINUX=enforcing
---
> SELINUX=disabled

I also disabled the firewall just in case it would cause problems:

[root@mongodb ~]# systemctl disable firewalld
Removed symlink /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.
Removed symlink /etc/systemd/system/basic.target.wants/firewalld.service.
[root@mongodb ~]# systemctl stop firewalld
[root@mongodb ~]# systemctl status firewalld
? firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; disabled; vendor preset: enabled)
   Active: inactive (dead)
     Docs: man:firewalld(1)
...

Lastly, in order to be able to access MongoDB from outside the VM I had to edit /etc/mongod.conf to allow access from all IP addresses:

[root@mongodb etc]# diff  mongod.conf mongod.conf.07012021
29c29
<   bindIp: 0.0.0.0 # Enter 0.0.0.0,:: to bind to all IPv4 and IPv6 addresses or, alternatively, use the net.bindIpAll setting.
---
>   bindIp: 127.0.0.1  # Enter 0.0.0.0,:: to bind to all IPv4 and IPv6 addresses or, alternatively, use the net.bindIpAll setting.

Of course, in a production system you would want to make this more secure, but this is just a quick and dirty test VM.

Finally, this command brings up the database:

systemctl start mongod

I ran this in a new root Putty window to get the ulimit settings. Not sure if that was necessary, but it did work.

I have a NAT network and port forwarding setup so that while MongoDB listens by default on port 27017 host localhost I setup VirtualBox to connect it to port 61029 host 127.0.0.1 on my laptop.

Since the programming language that I am most familiar with is Python (I have not learned any JavaScript) I setup a test connection to my new MongoDB database using the pymongo module.

I installed it like this:

pip install pymongo[srv]

Simple test program looks like this:

from pymongo import MongoClient
from pymongo.errors import ConnectionFailure

client = MongoClient('127.0.0.1', 61029)
try:
    # The ismaster command is cheap and does not require auth.
    client.admin.command('ismaster')
except ConnectionFailure:
    print("Server not available")

I got that from stackoverflow. I was also following the pymongo tutorial:

https://pymongo.readthedocs.io/en/stable/tutorial.html

One test program:

from pymongo import MongoClient

client = MongoClient('127.0.0.1', 61029)

db = client['test-database']

collection = db['test-collection']

import datetime
post = {"author": "Mike",
          "text": "My first blog post!",
          "tags": ["mongodb", "python", "pymongo"],
          "date": datetime.datetime.utcnow()}
          
posts = db.posts
post_id = posts.insert_one(post).inserted_id
print(type(post_id))
print(post_id)

print(db.list_collection_names())

import pprint
pprint.pprint(posts.find_one())

pprint.pprint(posts.find_one({"author": "Mike"}))

pprint.pprint(posts.find_one({"author": "Eliot"}))

pprint.pprint(posts.find_one({"_id": post_id}))

post_id_as_str = str(post_id)
pprint.pprint(posts.find_one({"_id": post_id_as_str}))

from bson.objectid import ObjectId

pprint.pprint(posts.find_one({"_id": ObjectId(post_id_as_str)}))

Its output:

<class 'bson.objectid.ObjectId'>
60df400f53f43d1c2703265c
['test-collection', 'posts']
{'_id': ObjectId('60de4f187d04f268e5b54786'),
 'author': 'Mike',
 'date': datetime.datetime(2021, 7, 1, 23, 26, 16, 538000),
 'tags': ['mongodb', 'python', 'pymongo'],
 'text': 'My first blog post!'}
{'_id': ObjectId('60de4f187d04f268e5b54786'),
 'author': 'Mike',
 'date': datetime.datetime(2021, 7, 1, 23, 26, 16, 538000),
 'tags': ['mongodb', 'python', 'pymongo'],
 'text': 'My first blog post!'}
None
{'_id': ObjectId('60df400f53f43d1c2703265c'),
 'author': 'Mike',
 'date': datetime.datetime(2021, 7, 2, 16, 34, 23, 410000),
 'tags': ['mongodb', 'python', 'pymongo'],
 'text': 'My first blog post!'}
None
{'_id': ObjectId('60df400f53f43d1c2703265c'),
 'author': 'Mike',
 'date': datetime.datetime(2021, 7, 2, 16, 34, 23, 410000),
 'tags': ['mongodb', 'python', 'pymongo'],
 'text': 'My first blog post!'}

I ran this on Python 3.9.6 so the strings like ‘Mike’ are not u’Mike’. It looks like the output on the tutorial is from some version of Python 2, so you get Unicode strings like u’Mike’ but on Python 3 strings are Unicode by default so you get ‘Mike’.

Anyway, I didn’t get any further than getting MongoDB installed and starting to run through the tutorial, but it is up and running. Might be helpful to someone else (or myself) if they are running through this to setup a test VM.

Bobby

About Bobby

I live in Chandler, Arizona with my wife and three daughters. I work for US Foods, the second largest food distribution company in the United States. I have worked in the Information Technology field since 1989. I have a passion for Oracle database performance tuning because I enjoy challenging technical problems that require an understanding of computer science. I enjoy communicating with people about my work.
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