DEV Community: Ravi Kumar Gupta

Encode Decode JWT

Ravi Kumar Gupta — Sun, 25 Jul 2021 15:58:27 +0000

JWT stands for JSON Web Tokens.

A simple function to encode the content -

'''
Encode the given text with given secret key. The default number of seconds for token validity is 600 seconds.
'''
def encode_token(text, secret_key, validity_seconds = 600):
    import datetime, jwt
    try:
        payload = {
            'exp': datetime.datetime.utcnow() + datetime.timedelta(days=0, seconds=validity_seconds),
            'iat': datetime.datetime.utcnow(),
            'secret': text
        }
        return jwt.encode(
            payload,
            secret_key,
            algorithm='HS256'
        )
    except Exception as e:
        return e

And to decode -

'''
Decode the encoded token with given secret_key
'''
def decode_token(auth_token, secret_key):
    import jwt
    try:
        payload = jwt.decode(auth_token, secret_key, algorithms='HS256')
        return {'auth': True, 'error': '', 'decoded': payload}
    except jwt.ExpiredSignatureError:
        return {'auth': False, 'error': 'Token expired'}
    except jwt.InvalidTokenError:
        return {'auth': False, 'error': 'Invalid token'}
    return {'auth': False, 'error': 'Some error'}

Let's get to work -

Define a secret

secret = 'This-is-my-super-secret'

Encode the content

encoded_data = encode_token('Something to encode', secret)
print(encoded_data)

This outputs as -

'eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJleHAiOjE2MjcyMjY4NDUsImlhdCI6MTYyNzIyNjI0NSwic2VjcmV0IjoiU29tZXRoaW5nIHRvIGVuY29kZSJ9.CombVr-757PXau8yeXtyjCLn54E3pGNntlnpoADnPRI'

If You copy this to https://jwt.io you will see -

Decode the token

To decode the data you need the same secret

decoded_data = decode_token(encoded_data, secret)
print(decoded_data['decoded']['secret'])

This outputs to -
'Something to encode'

If you try to decode using some other secret key, the data won't be decoded correctly

decoded_data = decode_token(encoded_data, 'some-other-secret')
print(decoded_data)

This output as -

{'auth': False, 'error': 'Invalid token'}

Hope these simple functions help you :)

You can follow me on Twitter — @kravigupta . You can also connect on LinkedIn — kravigupta.

Setting up Python Development Environment on Apple M1

Ravi Kumar Gupta — Sun, 25 Jul 2021 05:57:07 +0000

I recently moved to Apple M1. It was an awesome experience for my NodeJs, Java projects.

But a poor experience for python projects. I could not even install numpy properly.

I did not want to use Rosetta much. So, I had to install numpy using source. But then pandas did not install, then scipy has problems… Tired.

If you’ve reached here, you would have got a lot of articles where people tried to install by source or other ways. In this story, I am jumping straight to the solution which worked for me using miniforge

Install miniforge

brew install miniforge

Setup conda with your shell(zsh or bash, whatever you use)

conda init zsh

Create your venv using desired python version

conda create -n .venv python=3.9.2

This will create a virtual env for python 3.9.2. All the packages you install will go inside this environment.

Now you can just go your python code directory and activate virtual env.

cd /path/to/my/python/source/dir
conda activate .venv

Install the packages. Few packages I was not able to find in conda so if I install using pip that worked fine.

conda install numpy
conda install pandas

Or using Pip

pip install celery

That’s it, now you can simply run your app.

Hope this helps you. :)

You can follow me on Twitter — @kravigupta . You can also connect on LinkedIn — kravigupta.

Cheers!!

MongoDB Start with no-indexing

Ravi Kumar Gupta — Sun, 25 Jul 2021 05:53:44 +0000

Using MongoDB?

Ever faced this problem when your app is collecting huge data every day that any moment it may completely fill your storage and leave you with zero bytes.

After that, you can’t even login to the machine to fix the problem.

In your app, you can keep monitoring the free space and delete the old MongoDB data. But.. what if -

You have free space left, and MongoDB is re-building or building indexes and before your app checks again, the free space goes to zero?

But, you’re lucky to observe this before it happens. You go to MongoDB prompt and try to delete the data, but alas, MongoDB is building the indexes on the same collection you want to delete data from.

You won’t be able to do that.

You restart MongoDB hoping it would stop indexing and you would be able to delete.

That, doesn’t work either.

Okay, so you need to do this — start MongoDB with —-noIndexBuildRetry flag.

Edit the /etc/init.d/mongod file and replace the line —

- OPTIONS=" -f $CONFIGFILE"

with

- OPTIONS=" -f $CONFIGFILE --noIndexBuildRetry"

Restart MongoDB after the update. MongoDB will not attempt to fix or rebuild indexes.

Delete what you want from MongoDB prompt. Ensure to keep safe free space considering the indexes size.

Edit the /etc/init.d/mongod file again to remove the --noIndexBuildRetry and save.

Restart MongoDB.

Did it save your time? Let me know in the comments.

You can follow me on Twitter — @kravigupta . You can also connect on LinkedIn — kravigupta.