Continuous Integration with: GitHub, TravisCI and Heroku

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Today we’ll learn how to setup a simple project in order to use the Continuous Integration system TravisCI with Heroku and GitHub

1) Creating a new repository on GitHub

Follow the original documentation to create a new repository. Once it’s done. Let’s write a simple Flask application with a unit test to test it.

2) Cloning the repository into our machine

Once the repository is created, we need to clone it into our local machine. To clone, we need to execute:

git clone https://github.com/<git-user>/<repo-name>.git

3) Creating a virtualenv for our project

Assuming that you have virtualenv installed, now we have to create a new virtualenv in order to keep the dependencies isolated from our root system. So, to create it we need to execute:

virtualenv <virtualenv-name>

Once it’s created, to activate it we execute:

source <virtualenv-name>/bin/activate

• Obs: we don’t need to keep track of the virtualenv files, so, add the virtualenv directory on .gitignore.

4) Installing Flask into virtualenv

Now that we’re into the virtualenv, we need to install the libraries that we’ll use in this project: Flask.

pip install Flask pip freeze > requirements.txt

5) Creating the Flask app

We’ll create a very simple Flask app. The code is written below and it’s in the api.py file.

from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello, World!'

6) Creating the unit test file

The unit test file can be named as test.py and it will test the api.py.

import unittest
import api

class TestApp(unittest.TestCase):

    def setUp(self):
        self.app = api.app.test_client()

    def test_index(self):
        return_value = self.app.get('/')
        assert b'Hello, World' in return_value.data

if __name__ == '__main__':
    unittest.main()

Now that we have the api.py and the test.py we’ll create the TravisCI integration.

7) Creating the TravisCI integration

• In the profile page, click on Activate
• On Repository Acces, check the ‘Only select repositories’ and select the repository that you created above.
• Click in ‘Approve and install’
• Refresh the ‘Profile’ page and the new repository will be shown.

8) Configuring TravisCI

To configure TravisCI we need to create a file called .travis.yml and insert the following informations in it:

language: python
python:
  - "3.6"
install:
  - pip install -r requirements.txt
script:
  - pytest

and then, commit everything that we’ve done so far and check out the TravisCI console to see if everything’s ok.

9) Integrating with Heroku

Now that’s everything’s done with GitHub and TravisCI, we need to integrate it with Heroku. So:

• Create a new Heroku app
• Set the Deployment Method as GitHub, syncing with our repository created above.
• Check the box where is written Wait for CI to pass before deploy
• Then click in Enable Automatic Deploys.
• Create a new file called Procfile and insert the informations below in it:

web: FLASK_APP=api.py python -m flask run --host=0.0.0.0 --port=$PORT

Now we’ve done! Make some changes in the project and commit it to check if the TravisCI and the Heroku is working well together!