502 Bad Gateway with Nginx and Django

December 27, 2017 2.8k views
Nginx Django Ubuntu 16.04

Hi, I installed the one click Django app with Ubuntu 16.04, and followed the tutorial here: Link

Getting to the end successfully, I see the "Hello, world! This is our first view." when visiting my VPS IP address. I then got a DNS from freenom and pointed it to DigitalOceans nameservers as per this guide : Link

I can still connect via the IP address, but going to the domain name www.graphflow.tk (my registered DNS) shows a 502 error.

I've tried the following:

  • Adding ALLOWED_HOSTS in the django settins.py
  • Changing/adding the server name in the available sites file
  • turning on/off proxy buffering
  • Changing proxy buffering settings
  • Deleting and rebuilding the droplet
  • Checking UFW settings

Nginx, gunicorn and django all seem to be working fine

The nginx error log is showing:

*16 upstream prematurely closed connection while reading response header from upstream, client:[my IP], server: www.graphflow.tk, request: "GET /HTTP1.1", upstream: "http://unix:/home/django/gunicorn.socket:/", host: "graphflow.tk"

Config files:

user www-data;
worker_processes auto;
pid /run/nginx.pid;

events {
    worker_connections 768;
    # multi_accept on;
}

http {

    ##
    # Basic Settings
    ##

    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 65;
    types_hash_max_size 2048;

        proxy_buffering off;

    # server_tokens off;

    # server_names_hash_bucket_size 64;
    # server_name_in_redirect off;

    include /etc/nginx/mime.types;
    default_type application/octet-stream;

    ##
    # SSL Settings
    ##

    ssl_protocols TLSv1 TLSv1.1 TLSv1.2; # Dropping SSLv3, ref: POODLE
    ssl_prefer_server_ciphers on;

    ##
    # Logging Settings
    ##

    access_log /var/log/nginx/access.log;
    error_log /var/log/nginx/error.log;

    ##
    # Gzip Settings
    ##

    gzip on;
    gzip_disable "msie6";

    # gzip_vary on;
    # gzip_proxied any;
    # gzip_comp_level 6;
    # gzip_buffers 16 8k;
    # gzip_http_version 1.1;
    # gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;

    ##
    # Virtual Host Configs
    ##

    include /etc/nginx/conf.d/*.conf;
    include /etc/nginx/sites-enabled/*;
}


#mail {
#   # See sample authentication script at:
#   # http://wiki.nginx.org/ImapAuthenticateWithApachePhpScript
# 
#   # auth_http localhost/auth.php;
#   # pop3_capabilities "TOP" "USER";
#   # imap_capabilities "IMAP4rev1" "UIDPLUS";
# 
#   server {
#       listen     localhost:110;
#       protocol   pop3;
#       proxy      on;
#   }
# 
#   server {
#       listen     localhost:143;
#       protocol   imap;
#       proxy      on;
#   }
#}

"""
Django settings for django_project project.

Generated by 'django-admin startproject' using Django 1.8.7.

For more information on this file, see
https://docs.djangoproject.com/en/1.8/topics/settings/

For the full list of settings and their values, see
https://docs.djangoproject.com/en/1.8/ref/settings/
"""

# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
import os

BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))


# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/1.8/howto/deployment/checklist/

# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = '[secret key]'

# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True

ALLOWED_HOSTS = ['www.graphflow.tk', 'graphflow.tk', '[Droplet IP address']


# Application definition

INSTALLED_APPS = (
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
)

MIDDLEWARE_CLASSES = (
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
    'django.middleware.security.SecurityMiddleware',
)

ROOT_URLCONF = 'django_project.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [],
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

WSGI_APPLICATION = 'django_project.wsgi.application'


# Database
# https://docs.djangoproject.com/en/1.8/ref/settings/#databases

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    }
}


# Internationalization
# https://docs.djangoproject.com/en/1.8/topics/i18n/

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_L10N = True

USE_TZ = True


# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/1.8/howto/static-files/

STATIC_URL = '/static/'
# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
# Allow Django from all hosts. This snippet is installed from
# /var/lib/digitalocean/allow_hosts.py

import os
import netifaces

# Find out what the IP addresses are at run time
# This is necessary because otherwise Gunicorn will reject the connections
def ip_addresses():
    ip_list = []
    for interface in netifaces.interfaces():
        addrs = netifaces.ifaddresses(interface)
        for x in (netifaces.AF_INET, netifaces.AF_INET6):
            if x in addrs:
                ip_list.append(addrs[x][0]['addr'])
    return ip_list

# Discover our IP address
ALLOWED_HOSTS = ip_addresses()

upstream app_server {
    server unix:/home/django/gunicorn.socket fail_timeout=0;
}

server {
    listen 80 default_server;
    listen [::]:80 default_server ipv6only=on;

    root /usr/share/nginx/html;
    index index.html index.htm;

    client_max_body_size 4G;
    server_name www.graphflow.tk graphflow.tk [droplet IP];

    keepalive_timeout 5;
    proxy_ignore_client_abort on;

    # Your Django project's media files - amend as required
    location /media  {
        alias /home/django/django_project/django_project/media;
    }

    # your Django project's static files - amend as required
    location /static {
        alias /home/django/django_project/django_project/static;
    }

    # Proxy the static assests for the Django Admin panel
    location /static/admin {
       alias /usr/lib/python2.7/dist-packages/django/contrib/admin/static/admin/;
    }

    location / {
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header Host $host;
            proxy_redirect off;
            proxy_buffering off;

            proxy_pass http://app_server;
    }

}

Thanks,

Matt

PS. As default my django settings show SQLite as the database, but it's supposed to use postgreSQL is this correct?

1 Answer

Good morning Matt,

as I had the same problems as you, my solution was:
ALLOWEDHOSTS = [ 'domainname', 'dropelt_IP']

and add the bottom of settings.py

change:
ALLOWEDHOSTS = ipaddresses()

to

ALLOWEDHOSTS += ipaddresses()

Maybe this solution works for you as well, if you haven't solved your problem already.

Kind regards
Moritz

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