You have built a great streamlit app. So far, you only ran it locally on your computer on localhost:8501. Now you would like to share your app with others, but wonder how. This blogpost introduces you to one option: Heroku. Heroku is a platform as a service that allows you to deploy your apps (not just streamlit apps, but also jvm apps, ruby apps etc.). This post will guide you through the deployment of a streamlit app on Heroku. It’s free for non-commercial apps smaller than 300 MB. You need

  • a streamlit project with a repo on Github
  • your terminal

First you need to add 3 Files to your project’s repository on Github

A requirements.txt for your environment, setup.sh for creating a config file for your environment and Procfile, which will execute your app. You need to spell all file names correctly:

  • requirements.txt (no caps)
  • setup.sh (no caps)
  • Procfile (first letter cap, no extension)

All three files need to be located directly in the root directory of you project. Let’s look into each file in more detail.

1. Requirements.txt

Heroku will install all the packages needed for your app to run. It will look for requirements.txt. You can create it with

pip freeze > requirements.txt

Make sure you only have the relevant packages to speed up deployment.

2. Setup.sh

Just copypaste the following code in setup.sh. It will create a hidden folder called .streamlit/ and put a config file (config.toml) inside with port and server info.

mkdir -p ~/.streamlit/

echo "\
[server]\n\
headless = true\n\
enableCORS=false\n\
port = $PORT\n\
" > ~/.streamlit/config.toml

3. Procfile

Procfiles list process types. A process type is a named command that can be executed against your built application. Each line in the Procfile declares a process type (e.g. web for a webapp and worker for a worker…) and the command that you want to execute

<process type>: <command>

So have to specify the process type and the commands that should be executed. In our case we have a webapp (web:) and we need to execute setup.sh and run our streamlit app with streamlit run $Appname.py

web: sh setup.sh && streamlit run $Appname.py

One line. That’s it. Heroku will spinn up one web dyno automatically. A “dyno” is Heroku’s name for a lightweight Linux container. Web dynos should be created automatically. But if you get an error, like I did the first time, you can manually start the process with heroku ps:scale web=1.

Brief recap

Up till now, you should have created 3 additional files in your project folder.

  • requirements.txt
  • setup.sh
  • Procfile

Now let’s get your app up and running using your terminal with

Heroku

  1. Create an Account on Heroku and download Heroku Command Line Interface (CLI). This allows you to use your terminal to interact with Heroku.

  2. Log into Heroku. In your terminal, go to your project folder, type

    heroku login

    ` Press any key and it will direct you to the website so you can login.

  3. Create an app

    heroku create $AppName

    Your $AppName` will be in your Heroku url. You should now see your app in the personal section when you log into Heroku website.

  4. Push files to Heroku and automatically start the deployment. You just push the code from your local repository’s master branch to your Heroku remote

    git push heroku master

    ``

If you do not get an error, the deployment probably worked correctly. Double check the logs in your terminal. You should see something like

remote: -----> Discovering process types
remote:        Procfile declares types -> web
remote: 
remote: -----> Compressing...
remote:        Done: 155M
remote: -----> Launching...
remote:        Released v5
remote:        https://your-apps-name.Herokuapp.com/ deployed to heroku
remote: 
remote: Verifying deploy... done.
To https://git.heroku.com/your-apps-name.git

https://your-apps-name.heroku.com/ is the URL to your deployed project on Heroku. Congrats! If you want to redirect to another URL, just click through the Heroku web interface. It is quite intuitive to find your way around.