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How to deploy a Node.js application with a child process (python) in Heroku?

I'm trying to deploy a Node.js application with a child process that runs a machine learning algorithm. I can use this locally, but when I try to run at the Heroku server I recive some messages calling that are some libraries missing, like bellow:
ModuleNotFoundError: No module named 'pandas'
I tried to create manually the requirements.txt and put the necessary libraries there:
pandas
pymongo
dnspython
scikit-learn
scipy
selenium
webdriver-manager
textblob
But it doesn't work. Do I need to do some extra configuration?
Thank you so much for your help!

The way your Heroku dynos run your software is through something called a buildpack.
When you deploy an application to Heroku, it looks at your code and tries to figure out which programming language you are using, then based on that, will run your app using the corresponding buildpack.
For example, if you deploy an app to Heroku and the app has a package.json file in the root of your project directory, Heroku will assume your app is a JavaScript app and use the Node.js buildpack.
Buildpacks contain a number of pre-installed dependencies. For example, the Node.js buildpack contains node (so you can run your JavaScript code) as well as a number of Linux dependencies so that your app will be able to install common libraries/tools that might rely on them.
But... One downside of this buildpack strategy is that if you're deploying a Node.js app, for example, the default Node.js building will NOT come with Python and the various Python library dependencies installed. This is because Heroku supports a lot of different programming environments, and it would be slow/complex if there was just a single buildpack that had EVERYTHING installed. It'd be crazy!
So what you need to do, in your case, is use multiple buildpacks! Heroku has a way for you to enable multiple buildpacks for your app so that your app can have the Node.js dependencies as well as the Python dependencies, for example!
This article on Heroku's documentation site explains how to use multiple buildpacks for a given app.
Here are the specific instructions for simplicity's sake:
# This command will set your default buildpack to Node.js
$ heroku buildpacks:set heroku/nodejs
# This command will set it up so that the Heroku Python buildpack will run first
$ heroku buildpacks:add --index 1 heroku/python
By doing the above, you'll be able to have Heroku install your Python dependencies via a traditional requirements.txt file like you would with any normal Python application.

How can you change your python code after you deploy it to heroku using git , without downloading and reinstalling requirements everytime? [duplicate]

Im using django 3 and Python 3.7.4
I don't have any issues with the deployment and the project is working, it's just the first time I face this issue.
Normally when deploying to Heroku all packages in the requirements file get installed during the first deployment process, and any further deployment will only update or install the new packages the get added.
In my case, everytime I deploy, heroku is installing the whole packages again.
Please advise if there is a way to handle this issue.
thanks

This looks like a current issue with the Heroku python buildpack. As long as the issue persists the cache is cleared on every build, since the sqlite3 check is broken. Suggest upvoting the issue on GitHub.

heroku keeps installing django packages during each deployment

Im using django 3 and Python 3.7.4
I don't have any issues with the deployment and the project is working, it's just the first time I face this issue.
Normally when deploying to Heroku all packages in the requirements file get installed during the first deployment process, and any further deployment will only update or install the new packages the get added.
In my case, everytime I deploy, heroku is installing the whole packages again.
Please advise if there is a way to handle this issue.
thanks

This looks like a current issue with the Heroku python buildpack. As long as the issue persists the cache is cleared on every build, since the sqlite3 check is broken. Suggest upvoting the issue on GitHub.

"ModuleNotFoundError: No module named 'django'" when trying to deploy Django server on Azure

After I tried to deploy my Django website on Azure, I got an error saying:
ModuleNotFoundError: No module named 'django'
I added a requirements.txt in the root directory of my Django project, am I missing anything else? I've tried to install Django from Kudu BASH but it gets stuck on "Cleaning Up".
Here is the full error: https://pastebin.com/z5xxqM08
I built the site using Django-2.2 and Python 3.6.8.

Just summarized as an answer for other people. According to your error information, I can see that you tried to deploy your Django app to Azure WebApp on Linux based on Docker. So there are two offical documents will help as below.
Quickstart: Create a Python app in Azure App Service on Linux
Configure a Linux Python app for Azure App Service
The error ModuleNotFoundError: No module named 'django' indicated that there is not django package installed on the container of Azure Linux WebApp.
Due to the content of Container characteristics of #2 document above as below,
To install additional packages, such as Django, create a requirements.txt file in the root of your project using pip freeze > requirements.txt. Then, publish your project to App Service using Git deployment, which automatically runs pip install -r requirements.txt in the container to install your app's dependencies.
So the possible reason is the requirements.txt file not in the corrent path of your project or container after deployed, which path should be /home/site/wwwroot/requirements.txt on the container or the root of your project like the offical sample Azure-Samples/djangoapp on GitHub.

I had the same problem. requirements.txt was in my repository, but randomly I started getting the same error ModuleNotFoundError: No module named 'django' after changing a setting or restarting the service or something. Nothing I could do, change the setting, or reboot repeatedly fixed it. Finally what worked for me was this:
Make a small change to the code and commit it, and push it up to the app service.
This fixed it for me. It has happened a couple times now and every time this solution has worked for me. It seems like the App Service sometimes gets in this state and needs to be jostled with this trick?

How do you add a third party reusable app to django and deploy in openshift?

I've built a web app using django deployed on openshift. I'm trying to add the third party reusable app markdown-deux. I've followed the install instructions (used pip) and it works fine on the localhost development server.
I've added 'markdown_deux' to my settings.py and tried it with and without a requirements.txt. However, I still get a 500 error and from rhc tail the error "Import error: no module named markdown_deux".
I've tried restarting my app and resyncing the db but I'm still getting the same errors. I've RTFM but to no avail.

Openshift has mechanisms to automatically check and add dependencies after each git push, depending on your application type. So you don't need to install dependencies manually.
For python applications modify the projects setup.py.
Python application owners should modify setup.py in the root of the git repository with the list of dependencies that will be installed using easy_install. The setup.py should look something like this:
from setuptools import setup
setup(name='YourAppName',
version='1.0',
description='OpenShift App',
author='Your Name',
author_email='example#example.com',
url='http://www.python.org/sigs/distutils-sig/',
install_requires=['Django>=1.3', 'CloudMade'],
)
Read all details at the Openshift Help Center.

You've used pip to install it locally, but you actually need to install it on your server as well. Usually you would do that by adding it to the requirements.txt file and ensuring that your deployment process includes running pip install -r requirements.txt on the server.