Setting up JWT authentication in a new Django project

This article is an assembly-compilation of several (based on the first) articles, as a result of my studies on the topic of jwt authentication in jang with all that it implies. So it was not possible (at least in runet) to find a normal article, which tells from the stage of creating a project, startproject, screwing jwt authentication.

Having thoroughly investigated, I submit it to human judgment.

Links to used articles are attached:

1. https://thinkster.io/tutorials/django-json-api/authentication

   
   
   
   
   

2. https://simpleisbetterthancomplex.com/tutorial/2018/12/19/how-to-use-jwt-authentication-with-django-rest-framework.html

   
   
   
   
   

3. https://www.django-rest-framework.org/api-guide/authentication/

   
   
   
   
   

4. https://medium.com/django-rest/django-rest-framework-jwt-authentication-94bee36f2af8

   
   
   
   
   

---

Configuring JWT Authentication

Django comes with a session based authentication system and it works out of the box. This includes all models, views and templates that you may need to create and later login users. But here's the catch: Django's default authentication system only works with the traditional HTML request-response loop.

« '-' HTML»? , - (, ), . , «», - , - , , HTML , . , , « ».

, Django '-' HTML? , API, . , , JSON, HTML. JSON, , , . '-' JSON, , ( '-' HTML), . .

, Django , . , , . , . , , Django, , , .

, , :

1. User, Django

   
   
   
   
   

2. JSON HTML

   
   
   
   
   

3. HTML, Django

   
   
   
   
   

,

, Django . , , , , JSON Web Token Authentication (JWT ), .

Django (cookie). , (middlewares) , , . request.user



. , request.user



User



. , request.user



AnonymousUser



. , , request.user .

? , , , , request.user.isauthenticated()



, True



False



. request.user



AnonymousUser



, request.user.isauthenticated()



False. ( :) )

if request.user is not None and request.user.isauthenticated():



if request.user.isauthenticated():

, - !

, . , http://localhost:3000, http://localhost:5000. , , http://www.server.com http://www.clent.com. cookie, , , .

, cookie, (Cross-Origin Resource Sharing, CORS) (Cross-Site Request Forgery, CSRF), :

CORS

CSRF

,

/ .. . . . ( , , , , , , ""). , , . , . , , . , , . , , .

(ID) . , . , . - , . , .

JSON Web Tokens

JSON Web Token (. JWT) - (RFC 7519) , . JWT .

, , ? JWT , .

JSON Web Tokes ?

JWT :

1. JWT - . , JWT , . , , .

   
   
   
   
   

2. JWT , .

   
   
   
   
   

3. . , « » , .

   
   
   
   
   

,

, . , django-admin startproject json_auth_project



( , pip3 install django



).

. cd jsonauthproject



, python3 -m venv venv



. , venv



, . , . ./venv/bin/activate



. requirements.txt



, ( django



pip3 install django



). pip3 freeze > requirements.txt



( , / ). ./manage.py migrate



. , , . - ./manage.py runserver



. localhost



8000. http://localhost:8000. "The install worked successfully! Congratulations!" - :)

, (app) authentication



: ./manage.py startapp authentication



. apps/authentication/models.py



, . , .

User



UserManager



, :

import jwt

from datetime import datetime, timedelta

from django.conf import settings from django.contrib.auth.models import (
	AbstractBaseUser, BaseUserManager, PermissionsMixin
)

from django.db import models
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

Django Manager : createuser()



createsuperuser()



. Django, https://docs.djangoproject.com/en/3.1/topics/auth/customizing/#substituting-a-custom-user-model

UserManager



apps/authentication/models.py



( : https://docs.djangoproject.com/en/3.1/topics/db/managers/):

class UserManager(BaseUserManager):
    """
    Django ,      
     Manager.   BaseUserManager,    
      ,  Django    User ( ).
    """

    def create_user(self, username, email, password=None):
        """      ,   . """
        if username is None:
            raise TypeError('Users must have a username.')

        if email is None:
            raise TypeError('Users must have an email address.')

        user = self.model(username=username, email=self.normalize_email(email))
        user.set_password(password)
        user.save()

        return user

    def create_superuser(self, username, email, password):
        """       . """
        if password is None:
            raise TypeError('Superusers must have a password.')

        user = self.create_user(username, email, password)
        user.is_superuser = True
        user.is_staff = True
        user.save()

        return user
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, , , :

class User(AbstractBaseUser, PermissionsMixin):
    #       ,
    #       User  
    # .          
    #     .
    username = models.CharField(db_index=True, max_length=255, unique=True)

    #      ,      
    #          .
    #        ,   
    #      ,    
    #        (  ).
    email = models.EmailField(db_index=True, unique=True)

    #        ,  
    #    .    ,   
    #    ,       :)   
    #        .
    #  ,      ,     
    #   .
    is_active = models.BooleanField(default=True)

    #   ,       
    # .       .
    is_staff = models.BooleanField(default=False)

    #    .
    created_at = models.DateTimeField(auto_now_add=True)

    #       .
    updated_at = models.DateTimeField(auto_now=True)

    #  ,  Django
    #     .

    #  USERNAME_FIELD  ,     
    #    .       .
    USERNAME_FIELD = 'email'
    REQUIRED_FIELDS = ['username']

    #  Django,     UserManager
    #     .
    objects = UserManager()

    def __str__(self):
        """    (  ) """
        return self.email

    @property
    def token(self):
        """
              user.token, 
        user._generate_jwt_token().  @property   
        . token  " ".
        """
        return self._generate_jwt_token()

    def get_full_name(self):
        """
           Django   ,   
        .     ,    
         ,   username.
        """
        return self.username

    def get_short_name(self):
        """   get_full_name(). """
        return self.username

    def _generate_jwt_token(self):
        """
         - JSON,     
        ,     1   
        """
        dt = datetime.now() + timedelta(days=1)

        token = jwt.encode({
            'id': self.pk,
            'exp': int(dt.strftime('%s'))
        }, settings.SECRET_KEY, algorithm='HS256')

        return token.decode('utf-8')
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, :

1. models.CustomUser
   
   
   
   - , Django User
   
   
   
   https://docs.djangoproject.com/en/3.1/topics/auth/customizing/#django.contrib.auth.models.CustomUser

   
   
   
   
   

2. models.AbstractBaseUser



models.PermissionsMixin
   
   
   
   - https://docs.djangoproject.com/en/3.1/topics/auth/customizing/#django.contrib.auth.models.AbstractBaseUser https://docs.djangoproject.com/en/3.1/topics/auth/customizing/#django.contrib.auth.models.PermissionsMixin

   
   
   
   
   

3. models.BaseUserManager
   
   
   
   - UserManager
   
   
   
   https://docs.djangoproject.com/en/3.1/topics/auth/customizing/#django.contrib.auth.models.BaseUserManager

   
   
   
   
   

4. , Django, , (, db_index



unique
   
   
   
   ) https://docs.djangoproject.com/en/3.1/ref/models/fields/

   
   
   
   
   

AUTH_USER_MODEL

-, Django , - django.contrib.auth.models.User



. , . User



, , Django User



, .

Django: https://docs.djangoproject.com/en/3.1/topics/auth/customizing/#substituting-a-custom-user-model

, User



, .

Django User



, AUTH_USER_MODEL



project/settings.py



. , project/settings.py



:

#  Django      . 
# authentication.User  Django,      User  
# authentication.       INSTALLED_APPS.
AUTH_USER_MODEL = 'authentication.User'
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, , . - , Django , , - . , User.

• : ./manage.py makemigrations



./manage.py migrate
  
  
  
  , , . SQLite , . Django , AUTH_USER_MODEL
  
  
  
  , .

  
  
  
  
  

. . , :

./manage.py makemigrations

Django. , . , , .

authenticate



,

./manage.py makemigrations authentication

authentication



. . ,

./manage.py makemigrations

:

./manage.py migrate

makemigrations



, migrate



.

, User, , . , User. , .

:

./manage.py createsuperuser

Django - , . , . ! :)

, Django, :

./manage.py shell_plus



( ./manage.py shell



)

shell_plus django-extensions, (pip3 install django-extensions), shell_plus. , , INSTALLED_APPS. , .

, :

user = User.objects.first()
user.username
user.token
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, username



token



.

, . .

RegistrationSerializer

apps/authentication/serializers.py



:

from rest_framework import serializers

from .models import User


class RegistrationSerializer(serializers.ModelSerializer):
    """      . """

    # ,      8 ,   128,
    #           
    password = serializers.CharField(
        max_length=128,
        min_length=8,
        write_only=True
    )

    #          
    #   .      .
    token = serializers.CharField(max_length=255, read_only=True)

    class Meta:
        model = User
        #   ,      
        #  ,  ,   .
        fields = ['email', 'username', 'password', 'token']

    def create(self, validated_data):
        #   create_user,  
        #  ,    .
        return User.objects.create_user(**validated_data)
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, , .

ModelSerializer

RegistrationSerializer



, serializers.ModelSerializer



. serializers.ModelSerializer



- serializers.Serializer,



Django REST Framework (DFR). ModelSerializer



, Django. , : . create()



User.objects.create_user()



, . DRF .

RegistrationAPIView

. , (views) (endpoint), URL .

apps/authentication/views.py



:

from rest_framework import status
from rest_framework.permissions import AllowAny
from rest_framework.response import Response
from rest_framework.views import APIView

from .serializers import RegistrationSerializer


class RegistrationAPIView(APIView):
    """
       (  )    .
    """
    permission_classes = (AllowAny,)
    serializer_class = RegistrationSerializer

    def post(self, request):
        user = request.data.get('user', {})

        #   ,    - 
        # ,        .
        serializer = self.serializer_class(data=user)
        serializer.is_valid(raise_exception=True)
        serializer.save()

        return Response(serializer.data, status=status.HTTP_201_CREATED)
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

:

1. permission_classes
   
   
   
   - , , . .. ..

   
   
   
   
   

2. , , post - , . .

   
   
   
   
   

Django REST Framework (DRF) Permissions https://www.django-rest-framework.org/api-guide/permissions/

. Django 1.x => 2.x URL (path). URL- URL's, . , Django , .

apps/authentication/urls.py



:

from django.urls import path

from .views import RegistrationAPIView

app_name = 'authentication'
urlpatterns = [
    path('users/', RegistrationAPIView.as_view()),
]
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

Django . . . app_name = 'authentication'



, (including) . URL-.

project/urls.py



:

from django.urls import path

, , include()



django.urls

from django.urls import path, include

include()



, , .

:

urlpatterns = [
    path('admin/', admin.site.urls),
]
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, urls.py



:

urlpatterns = [
    path('admin/', admin.site.urls),
    path('api/', include('apps.authentication.urls', namespace='authentication')),
]
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

Postman

, User , , , . ( ) Postman ( https://learning.postman.com/docs/getting-started/introduction/).

POST localhost:8000/api/users/ :

{
    "user": {
        "username": "user1",
        "email": "user1@user.user",
        "password": "qweasdzxc"
    }
}

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

. ! , , . , "user". ( , ), DRF (renderer).

User

apps/authentication/renderers.py



:

import json

from rest_framework.renderers import JSONRenderer


class UserJSONRenderer(JSONRenderer):
    charset = 'utf-8'

    def render(self, data, media_type=None, renderer_context=None):
        #     token   ,   
        # .    ,   
        #      User.
        token = data.get('token', None)

        if token is not None and isinstance(token, bytes):
            #   ,  token     bytes.
            data['token'] = token.decode('utf-8')

        # ,         'user'.
        return json.dumps({
            'user': data
        })
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, .

, apps/auhentication/views.py



UserJSONRenderer



, :

from .renderers import UserJSONRenderer

, renderer_classes



RegistrationAPIView



:

renderer_classes = (UserJSONRenderer,)
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, UserJSONRenderer



, Postman'e . , "user".

, . , , . , API .

LoginSerializer

apps/authentication/serializers.py



:

from django.contrib.auth import authenticate
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, :

class LoginSerializer(serializers.Serializer):
    email = serializers.CharField(max_length=255)
    username = serializers.CharField(max_length=255, read_only=True)
    password = serializers.CharField(max_length=128, write_only=True)
    token = serializers.CharField(max_length=255, read_only=True)

    def validate(self, data):
        #   validate  ,   
        # LoginSerializer  valid.      
        #    ,    
        #   ,       .
        email = data.get('email', None)
        password = data.get('password', None)

        #  ,    .
        if email is None:
            raise serializers.ValidationError(
                'An email address is required to log in.'
            )

        #  ,    .
        if password is None:
            raise serializers.ValidationError(
                'A password is required to log in.'
            )

        #  authenticate  Django   , 
        #      -  
        #   .   email  username,    
        #  USERNAME_FIELD = email.
        user = authenticate(username=email, password=password)

        #     /  ,  authenticate
        #  None.     .
        if user is None:
            raise serializers.ValidationError(
                'A user with this email and password was not found.'
            )

        # Django   is_active   User.  
        # ,      .
        #  ,     True.
        if not user.is_active:
            raise serializers.ValidationError(
                'This user has been deactivated.'
            )

        #  validate     . 
        # ,    ..   create  update.
        return {
            'email': user.email,
            'username': user.username,
            'token': user.token
        }
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, .

LoginAPIView

apps/authentication/views.py



:

from .serializers import LoginSerializer, RegistrationSerializer
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, :

class LoginAPIView(APIView):
    permission_classes = (AllowAny,)
    renderer_classes = (UserJSONRenderer,)
    serializer_class = LoginSerializer

    def post(self, request):
        user = request.data.get('user', {})

        #  ,      save() , 
        #    .   ,     
        #  .  ,  validate()   .
        serializer = self.serializer_class(data=user)
        serializer.is_valid(raise_exception=True)

        return Response(serializer.data, status=status.HTTP_200_OK)
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, apps/authentication/urls.py



:

from .views import LoginAPIView, RegistrationAPIView
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

urlpatterns



:

urlpatterns = [
    path('users/', RegistrationAPIView.as_view()),
    path('users/login/', LoginAPIView.as_view()),
]
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

Postman

, , . :) Postman, http://localhost:8000/api/users/login/



, . , :

{
    "user": {
        "email": "email@email.email",
        "username": "admin",
        "token": "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpZCI6MSwiZXhwIjoxNjA1MTE3MjkwfQ.W8B6RY-jGO9PYDTzDWxhrkSHsTe1p3jlzq1BL7Tbwcs"
    }
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, token



, , .

-, . , , . - . -, non_field_errors



. , . , , , validate_email



, Django REST Framework , . , nonfield_errors



, , . -, , JSON ( ). , Django REST Framework.

EXCEPTION_HANDLER NON_FIELD_ERRORS_KEY

DRF EXCEPTION_HANDLER



. , , EXCEPTION_HANDLER



. NON_FIELD_ERRORS_KEY



, .

project/exceptions.py



, :

from rest_framework.views import exception_handler


def core_exception_handler(exc, context):
    #   ,      , 
    #      -, 
    # DRF.   ,      ,  
    #    DRF -    .
    response = exception_handler(exc, context)
    handlers = {
        'ValidationError': _handle_generic_error
    }
    #    .     ,
    #  ,         DRF.
    exception_class = exc.__class__.__name__

    if exception_class in handlers:
        #      -  :)  
        # ,      
        return handlers[exception_class](exc, context, response)

    return response


def _handle_generic_error(exc, context, response):
    #     ,    . 
    #    DRF      'errors'.
    response.data = {
        'errors': response.data
    }

    return response
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, project/settings.py



REST_FRAMEWORK



:

REST_FRAMEWORK = {
    'EXCEPTION_HANDLER': 'project.exceptions.core_exception_handler',
    'NON_FIELD_ERRORS_KEY': 'error',
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

DFR. , , , . ( / ) Postman - .

UserJSONRenderer

, / , . , "error", "user", . UserJSONRenderer



"error" . apps/authenticate/renderers.py



:

import json

from rest_framework.renderers import JSONRenderer


class UserJSONRenderer(JSONRenderer):
    charset = 'utf-8'

    def render(self, data, media_type=None, renderer_context=None):
        #     (,   
        #  ), data    error.  ,
        #   JSONRenderer   , 
        #    .
        errors = data.get('errors', None)

        #     token   ,   
        # .    ,   
        #      User.
        token = data.get('token', None)

        if errors is not None:
            #   JSONRenderer  .
            return super(UserJSONRenderer, self).render(data)

        if token is not None and isinstance(token, bytes):
            #   ,  token     bytes.
            data['token'] = token.decode('utf-8')

        # ,         'user'.
        return json.dumps({
            'user': data
        })
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, ( /) Postman - .

.

, . . .

UserSerializer

. , .

apps/authentication/serializers.py



:

class UserSerializer(serializers.ModelSerializer):
    """      User. """

    #     8  128 .   . 
    #     -,      
    # ,    ,     .
    password = serializers.CharField(
        max_length=128,
        min_length=8,
        write_only=True
    )

    class Meta:
        model = User
        fields = ('email', 'username', 'password', 'token',)

        #  read_only_fields     
        #   read_only = True,       .
        # ,       'read_only_fields'
        #   ,        .  
        #    min_length  max_length,
        #       .
        read_only_fields = ('token',)

    def update(self, instance, validated_data):
        """   User. """

        #     ,      
        # setattr. Django  ,   
        #   ''.  ,     
        #    'validated_data'    .
        password = validated_data.pop('password', None)

        for key, value in validated_data.items():
            #  ,   validated_data   
            #    User  .
            setattr(instance, key, value)

        if password is not None:
            # 'set_password()'   ,   
            #   ,       .
            instance.set_password(password)

        #  ,    ,     
        # User.  ,  set_password()   .
        instance.save()

        return instance
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, create , DRF serializers.ModelSerializer



. , , RegistrationSerializer



.

UserRetrieveUpdateAPIView

apps/authentication/views.py



:

from rest_framework import status
from rest_framework.generics import RetrieveUpdateAPIView
from rest_framework.permissions import AllowAny, IsAuthenticated
from rest_framework.response import Response
from rest_framework.views import APIView

from .renderers import UserJSONRenderer
from .serializers import (
    LoginSerializer, RegistrationSerializer, UserSerializer,
)
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, UserRetrieveUpdateView



:

class UserRetrieveUpdateAPIView(RetrieveUpdateAPIView):
    permission_classes = (IsAuthenticated,)
    renderer_classes = (UserJSONRenderer,)
    serializer_class = UserSerializer

    def retrieve(self, request, *args, **kwargs):
        #     .   , 
        #     User  -, 
        #    json   .
        serializer = self.serializer_class(request.user)

        return Response(serializer.data, status=status.HTTP_200_OK)

    def update(self, request, *args, **kwargs):
        serializer_data = request.data.get('user', {})

        #  ,    - ,   
        serializer = self.serializer_class(
            request.user, data=serializer_data, partial=True
        )
        serializer.is_valid(raise_exception=True)
        serializer.save()

        return Response(serializer.data, status=status.HTTP_200_OK)
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

apps/authentication/urls.py



, UserRetrieveUpdateView



:

from .views import (
    LoginAPIView, RegistrationAPIView, UserRetrieveUpdateAPIView
)
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

urlpatterns



:

urlpatterns = [
    path('user', UserRetrieveUpdateAPIView.as_view()),
    path('users/', RegistrationAPIView.as_view()),
    path('users/login/', LoginAPIView.as_view()),
]
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

Postman (GET localhost:8000/api/user/). , :

{
    "user": {
        "detail": "Authentication credentials were not provided."
    }
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

Django . , - , , , . JWT, Django, Django REST Framework (DRF).

apps/authentication/backends.py



:

import jwt

from django.conf import settings

from rest_framework import authentication, exceptions

from .models import User


class JWTAuthentication(authentication.BaseAuthentication):
    authentication_header_prefix = 'Token'

    def authenticate(self, request):
        """
         authenticate   ,   , 
           . 'authenticate'   
         :
            1) None -   None    .
              ,   ,    .
              , , ,     
            .
            2) (user, token) -    /
            ,    .    
              ,  ,   ,  
              .       
            AuthenticationFailed   DRF   .
        """
        request.user = None

        # 'auth_header'      :
        # 1)    (Token   )
        # 2)  JWT,      
        auth_header = authentication.get_authorization_header(request).split()
        auth_header_prefix = self.authentication_header_prefix.lower()

        if not auth_header:
            return None

        if len(auth_header) == 1:
            #   ,     
            return None

        elif len(auth_header) > 2:
            #   , -   
            return None

        # JWT    ,   
        #  bytes,     
        # Python3 (HINT:  PyJWT).    ,  
        #  prefix  token.     ,   
        # ,    ,    .
        prefix = auth_header[0].decode('utf-8')
        token = auth_header[1].decode('utf-8')

        if prefix.lower() != auth_header_prefix:
            #    ,    - .
            return None

        #     "",    .
        #        .
        return self._authenticate_credentials(request, token)

    def _authenticate_credentials(self, request, token):
        """
            .   -
           ,  -  .
        """
        try:
            payload = jwt.decode(token, settings.SECRET_KEY)
        except Exception:
            msg = ' .   '
            raise exceptions.AuthenticationFailed(msg)

        try:
            user = User.objects.get(pk=payload['id'])
        except User.DoesNotExist:
            msg = '     .'
            raise exceptions.AuthenticationFailed(msg)

        if not user.is_active:
            msg = '  .'
            raise exceptions.AuthenticationFailed(msg)

        return (user, token)
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, . , , , , , , - .

DRF

Django REST Framework, , , Django .

project/settings.py



REST_FRAMEWORK



:

REST_FRAMEWORK = {
    ...
    'DEFAULT_AUTHENTICATION_CLASSES': (
        'apps.authentication.backends.JWTAuthentication',
    ),
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

Postman

, , , , . , Postman (GET localhost:8000/api/user/). , . , ? . (PATCH localhost:8000/api/user/), . , , .

Let's summarize what we have done in this article. We have created a flexible user model (in the future, you can expand it as you like, adding different fields, additional models, etc.), three serializers, each of which perform its own clearly defined function. Created four endpoints that allow users to register, log in, receive and update information about their account. In my opinion, this is a very pleasant foundation, a basis on which you can build some new lamp project at your discretion :) (however, there are a bunch of areas that you can talk about for hours, for example, the next stage is spinning in the language about how wrap it all up in docker containers by screwing in postgres, radishes and celery).