Heroku is a platform as a service (PaaS) that enables developers to build, run, and operate applications entirely in the cloud. We have used Heroku to deploy our webapp that is builty using Streamlit. There are various steos involved in the deployment which have been specified below with the necessary code, so that it is easier for anyone else to deploy a similar application.

How to deploy a Streamlit webapp on Heroku??

Make sure that your terminal is in your project folder. When you launch your project into the cloud, you need to create a requirements.txt file so that the server knows what to download to run your code. The library pipreqs can autogenerate requirements.

Use the following command in your terminal to install the pipreqs library :

pip install pipreqs

Then once it’s downloaded, just step out of the folder, run the following command, and in the folder, you should find your requirements.txt file.

pipreqs <directory-path>

The requirements file would contain the names of the libraries and their versions.

Example:

• altair==4.1.0
• streamlit==0.64.0
• matplotlib==3.2.2
• pandas==1.0.5
• plotly==4.9.0
• numpy==1.18.5
• dash==1.17.0

The setup.sh file contains some commands to set the problem on the Heroku side, so create a setup.sh file (you can use the nano command) and save the following in that file (change the email in the middle of the file to your correct email).

Make sure that your terminal is in your project folder.

Type the command

nano setup.sh

Now you will see a setup.sh file has been opened. Copy one of the codes that you like and paste it in the setup.sh file

setup.sh (without email verification - preferrable)

mkdir -p ~/.streamlit/

echo "

[server]\\n

headless = true\\n

enableCORS=false\\n

port = $PORT\\n

\\n

" > ~/.streamlit/config.toml

setup.sh (with email verification - not preferrable)

mkdir -p ~/.streamlit/
echo "\\
[general]\\n\\
email = \\"[email protected]\\"\\n\\
" > ~/.streamlit/credentials.toml
echo "\\
[server]\\n\\
headless = true\\n\\
enableCORS=false\\n\\
port = $PORT\\n\\

Procfile

Again, make sure that your terminal is in your project folder.

Type the command:

nano Procfile  

(Procfile here is case sensitive - type it as it is mentioned)

Now insert the following piece of code in the Procfile file:

web: sh setup.sh && streamlit run [name-of-app].py

Note: [name-of-app] being the name of your project's main.py file

Heroku builds systems using Git and it’s pretty easy to get set up. Git is a version control system and runs as default on a lot of operating systems. Check if you have it (if yes then skip this step). If not, install it.

Open terminal in your project folder and run the following commands :

git init

This initialises a git repository in your project folder and you should see something like the following print out:

Initialized empty Git repository in /Users/…

(If you are doing this for the first time make sure you visit - https://devcenter.heroku.com/articles/heroku-cli and create your account there)

Once you’ve downloaded the Heroku CLI , run the following login command:

heroku login

This opens up a browser window, from which you can log in. Once you’re in, it’s time to create your cloud instance. Run the following command

C:\Users...> heroku create

Now you’ll see that Heroku will create some oddly named instance (don’t worry, it’s just how it is):

Example:

Creating app... done, warm-eyrie-XXXX

So Heroku created an app called ‘warm-eyrie’ for me. Not sure why, but I’ll take it. Now all that’s remaining is to move the code across, so in our project folder we run the following commands:

git add .
git commit -m "Enter your message here"
git push heroku master

Once it’s merged, the Heroku application will start downloading and installing everything on the server side. This takes a couple of minutes but if all is good, then you should something like:

remote: Verifying deploy... done.

Your job is done! If you copy the url it gives you in the command line into your browser, you’ll see that you can now run your application online. You can even check it on your mobile phone, it’s perfect!

If you want to update your code, you can just update it as normal, then do the following again:

git add .
git commit -m "Enter your message here"
git push heroku master
heroku ps:scale web=1

If you use the Heroku CLI to rename an app from inside its associated Git repository, your local Heroku remote is updated automatically. However, other instances of the repository must update the remote’s details manually.

You can run the following commands to update the remote’s details in other repository instances:

$ git remote rm heroku
$ heroku git:remote -a newname

Replace newname with the new name of the app, as specified in the rename command.