Heroku "Application error" on a Django/React app - reactjs

Question

I'm currently working on a to do list project for my studies and I was able to chose the technologies involved.
I decided to use Django, React, MongoDB for the app and Heroku for the hosting. I had previous experience with React MongoDB and NodeJS and managed to host the app on heroku very easily.
However with this new project I always get an "Application Error" whenever I try to access the website.
I struggled to find up to date information on how to properly host a Django/React app on Heroku and none of the answers I found solved my problem.
What concerns me the most is that the deployment log do not show any major issue during the build process :
> Enumerating objects: 7, done.
Counting objects: 100% (7/7), done.
Delta compression using up to 8 threads
Compressing objects: 100% (4/4), done.
Writing objects: 100% (4/4), 356 bytes | 356.00 KiB/s, done.
Total 4 (delta 3), reused 0 (delta 0)
remote: Compressing source files... done.
remote: Building source:
remote:
remote: -----> Building on the Heroku-20 stack
remote: -----> Using buildpacks:
remote: 1. heroku/nodejs
remote: 2. heroku/python
remote: -----> Node.js app detected
remote:
remote: -----> Creating runtime environment
remote:
remote: NPM_CONFIG_LOGLEVEL=error
remote: NODE_VERBOSE=false
remote: NODE_ENV=production
remote: NODE_MODULES_CACHE=true
remote:
remote: -----> Installing binaries
remote: engines.node (package.json): unspecified
remote: engines.npm (package.json): unspecified (use default)
remote:
remote: Resolving node version 16.x...
remote: Downloading and installing node 16.16.0...
remote: Using default npm version: 8.11.0
remote:
remote: -----> Restoring cache
remote: - npm cache
remote:
remote: -----> Installing dependencies
remote: Installing node modules
remote:
remote: added 1457 packages, and audited 1458 packages in 12s
remote:
remote: 205 packages are looking for funding
remote: run `npm fund` for details
remote:
remote: 6 high severity vulnerabilities
remote:
remote: To address all issues (including breaking changes), run:
remote: npm audit fix --force
remote:
remote: Run `npm audit` for details.
remote:
remote: -----> Build
remote: Running build
remote:
remote: > frontend#0.1.0 build
remote: > react-scripts build
remote:
remote: Creating an optimized production build...
remote: Compiled with warnings.
remote:
remote: [eslint]
remote: src/components/AppNavbar.js
remote: Line 1:10: 'Collapse' is defined but never used no-unused-vars
remote: Line 53:19: The href attribute requires a valid value to be accessible. Provide a valid, navigable address as the href value. If you cannot provide a valid href, but still need the element to resemble a link, use a button and change it with appropriate styles. Learn more: https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/HEAD/docs/rules/anchor-is-valid.md jsx-a11y/anchor-is-valid
remote: Line 57:25: The href attribute is required for an anchor to be keyboard accessible. Provide a valid, navigable address as the href value. If you cannot provide an href, but still need the element to resemble a link, use a button and change it with appropriate styles. Learn more: https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/HEAD/docs/rules/anchor-is-valid.md jsx-a11y/anchor-is-valid
remote: Line 58:25: The href attribute is required for an anchor to be keyboard accessible. Provide a valid, navigable address as the href value. If you cannot provide an href, but still need the element to resemble a link, use a button and change it with appropriate styles. Learn more: https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/HEAD/docs/rules/anchor-is-valid.md jsx-a11y/anchor-is-valid
remote:
remote: src/components/Body.js
remote: Line 13:6: React Hook useEffect has a missing dependency: 'dispatch'. Either include it or remove the dependency array react-hooks/exhaustive-deps
remote:
remote: src/components/TaskElement.js
remote: Line 59:11: The href attribute is required for an anchor to be keyboard accessible. Provide a valid, navigable address as the href value. If you cannot provide an href, but still need the element to resemble a link, use a button and change it with appropriate styles. Learn more: https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/HEAD/docs/rules/anchor-is-valid.md jsx-a11y/anchor-is-valid
remote: Line 65:13: The href attribute is required for an anchor to be keyboard accessible. Provide a valid, navigable address as the href value. If you cannot provide an href, but still need the element to resemble a link, use a button and change it with appropriate styles. Learn more: https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/HEAD/docs/rules/anchor-is-valid.md jsx-a11y/anchor-is-valid
remote:
remote: Search for the keywords to learn more about each warning.
remote: To ignore, add // eslint-disable-next-line to the line before.
remote:
remote: File sizes after gzip:
remote:
remote: 89.81 kB build/static/js/main.67b777d4.js
remote: 27.94 kB build/static/css/main.fc8229bc.css
remote: 1.78 kB build/static/js/787.cda612ba.chunk.js
remote:
remote: The project was built assuming it is hosted at /.
remote: You can control this with the homepage field in your package.json.
remote:
remote: The build folder is ready to be deployed.
remote: You may serve it with a static server:
remote:
remote: npm install -g serve
remote: serve -s build
remote:
remote: Find out more about deployment here:
remote:
remote: https://cra.link/deployment
remote:
remote:
remote: -----> Caching build
remote: - npm cache
remote:
remote: -----> Pruning devDependencies
remote:
remote: up to date, audited 1458 packages in 3s
remote:
remote: 205 packages are looking for funding
remote: run `npm fund` for details
remote:
remote: 6 high severity vulnerabilities
remote:
remote: To address all issues (including breaking changes), run:
remote: npm audit fix --force
remote:
remote: Run `npm audit` for details.
remote:
remote: -----> Build succeeded!
remote: -----> Python app detected
remote: -----> Using Python version specified in runtime.txt
remote: ! Python has released a security update! Please consider upgrading to python-3.8.13
remote: Learn More: https://devcenter.heroku.com/articles/python-runtimes
remote: -----> No change in requirements detected, installing from cache
remote: -----> Using cached install of python-3.8.10
remote: -----> Installing pip 22.1.2, setuptools 60.10.0 and wheel 0.37.1
remote: -----> Installing dependencies with Pipenv 2020.11.15
remote: Installing dependencies from Pipfile...
remote: -----> Installing SQLite3
remote: -----> Discovering process types
remote: Procfile declares types -> web
remote:
remote: -----> Compressing...
remote: Done: 153M
remote: -----> Launching...
remote: Released v11
remote: https://task-list-manager-gf.herokuapp.com/ deployed to Heroku
remote:
remote: This app is using the Heroku-20 stack, however a newer stack is available.
remote: To upgrade to Heroku-22, see:
remote: https://devcenter.heroku.com/articles/upgrading-to-the-latest-stack
remote:
remote: Verifying deploy... done.
To https://git.heroku.com/task-list-manager-gf.git
15c029d..a5e2c42 master -> master
The only errors displayed in this log are related to react and they do not prevent the app from working perfectly fine locally.
I figured the problem might reside in my settings.py file:
from pathlib import Path
import os
# Build paths inside the project like this: BASE_DIR / 'subdir'.
BASE_DIR = Path(__file__).resolve().parent.parent
# Quick-start development settings - unsuitable for production
# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = '#######################################################""'
DEBUG = False
ALLOWED_HOSTS = ['localhost:3000/', '127.0.0.1', 'task-list-manager-gf.herokuapp.com/']
# Application definition
INSTALLED_APPS = [
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'api.apps.ApiConfig',
'corsheaders',
'pymongo'
]
CORS_ORIGIN_ALLOW_ALL = True
MIDDLEWARE = [
'corsheaders.middleware.CorsMiddleware',
'django.middleware.security.SecurityMiddleware',
'whitenoise.middleware.WhiteNoiseMiddleware',
'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',
]
STATICFILES_STORAGE = 'whitenoise.storage.CompressedManifestStaticFilesStorage'
ROOT_URLCONF = 'backend.urls'
TEMPLATES = [
{
'BACKEND': 'django.template.backends.django.DjangoTemplates',
'DIRS': [os.path.join(BASE_DIR, 'build')],
'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 = 'backend.wsgi.application'
# Database
DATABASES = {
'default': {
'ENGINE': '',
'NAME': '',
}
}
# Password validation
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
LANGUAGE_CODE = 'en-us'
TIME_ZONE = 'UTC'
USE_I18N = True
USE_TZ = True
# Static files (CSS, JavaScript, Images)
STATIC_URL = 'static/'
STATICFILES_DIRS = [
os.path.join(BASE_DIR, 'build/static')
]
STATIC_ROOT = os.path.join(BASE_DIR, 'staticfiles')
# Default primary key field type
DEFAULT_AUTO_FIELD = 'django.db.models.BigAutoField'
The current file structure of my app looks like this :
Main project directory
There is a 'build' and 'staticfile' folder because I tried to use the python manage.py collectstatic command to see if the problem came from python not being able to access React files.
my requirement.txt is the following :
asgiref==3.5.2
backports.zoneinfo==0.2.1
Django==4.0.6
django-cors-headers==3.13.0
dnspython==2.2.1
gunicorn==20.1.0
pymongo==4.2.0
sqlparse==0.4.2
whitenoise==6.2.0
and my package.json file :
{
"name": "frontend",
"proxy": "http://localhost:8000",
"version": "0.1.0",
"private": true,
"dependencies": {
"#primer/octicons-react": "^17.3.0",
"#reduxjs/toolkit": "^1.8.3",
"#testing-library/jest-dom": "^5.16.4",
"#testing-library/react": "^13.3.0",
"#testing-library/user-event": "^13.5.0",
"bootstrap": "^5.2.0",
"react": "^18.2.0",
"react-dom": "^18.2.0",
"react-redux": "^8.0.2",
"react-scripts": "5.0.1",
"web-vitals": "^2.1.4"
},
"scripts": {
"start": "react-scripts start",
"build": "react-scripts build",
"test": "react-scripts test",
"eject": "react-scripts eject"
},
"eslintConfig": {
"extends": [
"react-app",
"react-app/jest"
]
},
"browserslist": {
"production": [
">0.2%",
"not dead",
"not op_mini all"
],
"development": [
"last 1 chrome version",
"last 1 firefox version",
"last 1 safari version"
]
}
}
After looking into the app log I found the error below. Heroku cannot find the gunicorn despite the package being referenced in the requirement.txt file.
2022-07-26T17:47:34.919084+00:00 heroku[web.1]: State changed from crashed to starting2022-07-26T17:47:44.388599+00:00 heroku[web.1]: Starting process with command `gunicorn backend.wsgi --log-file -`2022-07-26T17:47:45.219051+00:00 app[web.1]: bash: gunicorn: command not found2022-07-26T17:47:45.331605+00:00 heroku[web.1]: Process exited with status 1272022-07-26T17:47:45.370368+00:00 heroku[web.1]: State changed from starting to crashed2022-07-26T18:49:00.301044+00:00 heroku[web.1]: State changed from crashed to starting2022-07-26T18:49:10.354539+00:00 heroku[web.1]: Starting process with command `gunicorn backend.wsgi --log-file -`2022-07-26T18:49:11.240683+00:00 app[web.1]: bash: gunicorn: command not found2022-07-26T18:49:11.362628+00:00 heroku[web.1]: Process exited with status 1272022-07-26T18:49:11.551249+00:00 heroku[web.1]: State changed from starting to crashed2022-07-26T22:33:39.008533+00:00 heroku[web.1]: State changed from crashed to starting2022-07-26T22:33:51.671289+00:00 heroku[web.1]: Starting process with command `gunicorn backend.wsgi --log-file -`2022-07-26T22:33:52.841248+00:00 app[web.1]: bash: gunicorn: command not found2022-07-26T22:33:54.073693+00:00 heroku[web.1]: State changed from starting to crashed2022-07-26T22:33:52.982851+00:00 heroku[web.1]: Process exited with status 127
272022-07-26T17:47:45.370368+00:00 heroku[web.1]: State changed from starting to crashed
All the source code is available on my git : https://github.com/GuillaumeFavrot/TaskListManager.live
I'm running out of ideas so if you see something I'm missing that'd be great and let me know if more information is required.
Thanks!

Answer 1

Try setting allowed host in your settings.py to *