Heroku¶

Heroku is a “platform as a service (PaaS) that enables developers to build, run, and operate applications entirely in the cloud.” Heroku even offers a free plan.

Here’s how to deploy your implementation of, say, C$50 Finance to Heroku from GitHub.

Watch Brian’s seminar to learn about git and GitHub, if not already familiar.
Sign up for free, private GitHub repositories at https://education.github.com/discount_requests/new, if you haven’t already.
Create a new private repository at https://github.com/new (called, e.g., finance).
Take note of the HTTPS URL of the repository (e.g., https://github.com/username/finance.git, where username is your own GitHub username).
Change to your finance directory in CS50 IDE, as via cd.
Create a git repo therein.
```
git init
```
Add the GitHub repository as a “remote,” where username is your own GitHub username.
```
git remote add origin https://github.com/username/finance.git
```
In the requirements.txt file inside of your finance directory, add gunicorn and psycopg2, each on separate lines.
Push your code to GitHub.
```
git add -A
git commit -m "first commit"
git push -u origin master
```
If you visit https://github.com/username/finance, where username is your own GitHub username, you should see your code in the repository.
Sign up for a free Heroku account at https://signup.heroku.com/, if you don’t have one already.
Create a new app at https://dashboard.heroku.com/new-app.
Configure your app at https://dashboard.heroku.com/apps/app-name/deploy/github, where app-name is your Heroku app’s name.
- Add this app to a pipeline: No need to configure; leave as is.
- Deployment method: Select GitHub, then click Connect to GitHub. If prompted to log into GitHub, click Authorize heroku.
- App connected to GitHub: Search for your app’s repository (e.g., username/finance, where username is your own GitHub username), then click Connect.
- Automatic deploys: Click Enable Automatic Deploys.
Configure your app at https://dashboard.heroku.com/apps/app-name/settings, where app-name is your Heroku app’s name.
1. Click Reveal Config Vars.
2. Add a new variable called API_KEY, the value of which is your API token for IEX. Recall that, after registering for a developer account at https://iexcloud.io/, you can obtain your API token under API Tokens. Be sure to use your PUBLISHABLE token as the value for API_KEY, not your SECRET token.
Search for and provision Heroku Postgres at https://dashboard.heroku.com/apps/app-name/resources, where app-name is your Heroku app’s name; select a Plan name of Hobby Dev — Free.
At https://dashboard.heroku.com/apps/app-name/resources, where app-name is your Heroku app’s name, click Heroku Postgres :: Database. In the tab that opens, click Settings, then click View Credentials…. Highlight and copy the URI that appears.
In CS50 IDE, open application.py in finance/ and replace
```
db = SQL("sqlite:///finance.db")
```
with
```
db = SQL(os.getenv("DATABASE_URL"))
```
so that the CS50 Library will connect to your PostgreSQL database instead of your SQLite database. Be sure to add
```
import os
```
atop application.py, if not there already.
In CS50 IDE, execute the below to import finance.db into your PostgreSQL database, where URI is that same URI. Be sure to append ?sslmode=require to the URI. Note that disabling SSL’s certification verification with --no-ssl-cert-verification is not recommended in general but seems to be a temporary workaround.
```
pgloader --no-ssl-cert-verification finance.db URI?sslmode=require
```
Thereafter, if you’d like to browse or edit your PostgreSQL database, you can use Adminer (a tool like phpLiteAdmin for PostgreSQL databases), at adminer.cs50.net. Log in using your database’s credentials: at https://dashboard.heroku.com/apps/app-name/resources, where app-name is your Heroku app’s name, click Heroku Postgres :: Database. In the tab that opens, click Settings, then click View Credentials….
Create a new file in CS50 IDE called Procfile in finance/ whose contents are:
```
web: gunicorn application:app
```
That file will tell Heroku to look in a file called application.py for a variable called app and serve it with Gunicorn, a production-quality web server. (Flask’s built-in web server is “good enough for testing but probably not what you want to use in production.”)
Add that file to your repository and push it to GitHub.
```
git add -A
git commit -m "added Procfile"
git push
```
If you visit https://app-name.herokuapp.com/, where app-name is your Heroku app’s name, you should see your app! If you instead see some error, visit https://dashboard.heroku.com/apps/app-name/logs, where app-name is your app’s name, to diagnose! Each time you add (new or changed) files to your repository and push to GitHub hereafter, your app will be re-deployed to Heroku.