图像从部署到 heroku 的 django web 应用程序消失

Question

I am working on a django project, writing rest APIs with django rest framework to use them in android application, my main idea is develop back end in django and front end in android, project is deployed on heroku. My application contains some inventory with the item pictures, issue is while i am uploading the image it successfully upload the image but after some time or more specifically after some hours the image disappears by it self.

Here is my setting.py file

"""
Django settings for forBirds project.

Generated by 'django-admin startproject' using Django 3.0.6.

For more information on this file, see
https://docs.djangoproject.com/en/3.0/topics/settings/

For the full list of settings and their values, see
https://docs.djangoproject.com/en/3.0/ref/settings/
"""

import os
import dj_database_url

# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
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/3.0/howto/deployment/checklist/

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

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

ALLOWED_HOSTS = ['*']

# Application definition

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'account',
    'rest_framework',
    'rest_framework.authtoken',
    'Birds',
]

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
    'whitenoise.middleware.WhiteNoiseMiddleware',
]

ROOT_URLCONF = 'forBirds.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 = 'forBirds.wsgi.application'

# Database
# https://docs.djangoproject.com/en/3.0/ref/settings/#databases

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': '',
        "USER": "",
        "PASSWORD": "",
        "HOST": "",
        "PORT": "",
    }
}

# Password validation
# https://docs.djangoproject.com/en/3.0/ref/settings/#auth-password-validators


REST_FRAMEWORK = {
    "DEFAULT_AUTHENTICATION_CLASSES": (
        "rest_framework.authentication.BasicAuthentication",
        "rest_framework.authentication.SessionAuthentication",
        "rest_framework.authentication.TokenAuthentication"
    ),
    "DEFAULT_PERMISSIONS_CLASSES": (
        "rest_framework.permissions.IsAuthenticated"
    ),
    "DEFAULT_PAGINATION_CLASS": "rest_framework.pagination.PageNumberPagination",
    "PAGE_SIZE": 1,
}
AUTH_USER_MODEL = 'account.Account'

AUTH_PASSWORD_VALIDATORS = [
    {
        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]

# Internationalization
# https://docs.djangoproject.com/en/3.0/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/1.11/howto/static-files/
PROJECT_ROOT = os.path.join(os.path.abspath(__file__))
STATIC_ROOT = os.path.join(BASE_DIR, 'staticfiles')
STATIC_URL = '/static/'

MEDIA_URL = '/media/'
MEDIA_ROOT = os.path.join(BASE_DIR, 'media')

# Extra lookup directories for collectstatic to find static files
STATICFILES_DIRS = (
    os.path.join(PROJECT_ROOT, 'static'),
)

#  Add configuration for static files storage using whitenoise
STATICFILES_STORAGE = 'whitenoise.storage.CompressedManifestStaticFilesStorage'

prod_db = dj_database_url.config(conn_max_age=500)
DATABASES['default'].update(prod_db)

Answer 1

The Heroku filesystem is ephemeral - that means that any changes to the filesystem whilst the dyno is running only last until that dyno is shut down or restarted. Each dyno boots with a clean copy of the filesystem from the most recent deploy.

Instead of storing uploaded files to disk, the best practice is to leverage a cloud file storage service such as Amazon's S3.

Answer 2

When you upload a file to the Django admin, it looks at the DEFAULT_FILE_STORAGE settings configuration to determine how to store that file. By default , it uses django.core.files.storage.FileSystemStorage , which means that it is writing those uploaded files to the dyno's filesystem at the location defined by MEDIA_ROOT .

The issue is, dynos are ephemeral, and they can be destroyed, restarted, and moved without any warning, which replaces your filesystem . This means that those uploaded files are just deleted without a trace, but the ImageField reference still thinks they are there.

The solution to this issue is to update the project's DEFAULT_FILE_STORAGE to use something permanent, such as an s3-compatible object store . In Heroku & Django land, a common solution is to use django-storages alongside Heroku's Bucketeer add-on . This solution uploads your files to a persistent data store that survives dyno restarts, instead of writing to the dyno file system which gets deleted frequently.

I know that this can be daunting, so I wrote up this article with a pretty good write-up of the Heroku + Bucketeer process.