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Elsa Quickstart

This document will help you to set up an elsa powered website on your domain. It assumes you are already familiar with git.

Overview

In this tutorial, we will:

  1. create a GitHub repository with a simple Flask website
  2. set up a domain to serve the website from
  3. set up Travis CI to run elsa and deploy the website to GitHub pages

Step 1: Create a repository on GitHub

Before you start, you'll need a GitHub repository. Note that elsa is meant to be run on Travis CI and Travis CI only supports GitHub. Other uses might be possible but are not covered in this tutorial.

If you already know how to create repositories on GitHub, feel free to skip this part of the tutorial and continue with the next step.

Follow the GitHub documentation to set up a new repository, then clone it.

You can use both public and private repositories with elsa. This tutorial assumes a public repository, but will give you a heads up if you use a private one.

Step 2: Create a Flask website powered by Elsa

In this tutorial we'll just create a very simple Flask website that says hello world. You are of course encouraged to create more sophisticated websites. Please read the excellent Flask's own Qucikstart to learn more about creating websites in this popular Python web framework.

Our simple website will be defined in just one file, although it is of course possible to have it spread across several files or even create a module. The name of that file is not important, but it is generally not advised to use names colliding with stuff you are going to import from Python, such as elsa.py or flask.py. In this tutorial, we'll name it website.py.

Our simple Flask website may look like this:

from flask import Flask


app = Flask('website')


@app.route('/')
def index():
    return '<html><body>Hello world!</body></html>'

When you'll create more sophisticated websites, read trough the Frozen-Flask documentation about finding URLs and filenames and MIME types.

Once you have your Flask-powered website, add elsa at the bottom of that file:

if __name__ == '__main__':
    from elsa import cli
    cli(app, base_url='https://example.com')

Make sure to add your own base URL instead of https://example.com. The base URL consists of https:// and your domain name. (You can also use http:// with Elsa, but we don't recommend that.)

To test your new website, you'll need to install elsa. The best way is to use the Python virtual environment:

$ python3 -m venv __env__
$ . __env__/bin/activate
(__env__)$ python -m pip install elsa

The above snippet assumes you are running Linux or Mac OS X, consult the virtual environment documentation if you happen to use Windows. If you are not yet familiar with virtual environments, note that they do not belong in git and make sure you add __env__ to your .gitignore file.

Now run your website on your own computer like this:

(__env__)$ python website.py serve
 * Running on http://127.0.0.1:8003/ (Press CTRL+C to quit)
 * Restarting with stat
 * Debugger is active!
 * Debugger pin code: 237-729-566

You can use your web browser to open http://localhost:8003/ and you should see your website. You can terminate the local server by pressing Ctrl+C in the terminal as said in the output.

If it worked, you can freeze your website and test if it works frozen:

(__env__)$ python website.py freeze --serve
Generating HTML...
 * Running on http://127.0.0.1:8003/ (Press CTRL+C to quit)

The website should be available on http://localhost:8003/ once again, this time served from static HTML pages. Press Ctrl+C to terminate the server once again and you are ready to set up a deployment of the website using Travis CI.

Step 3: Change your DNS settings

In order to host your website on GitHub pages on your own domain, you'll need to change your DNS settings. GitHub pages documentation covers that for:

Note that the documentation talks about adding a custom domain to your GitHub Pages site and about a CNAME file. You don't have to worry about either, elsa will do that for you.

It should be possible to use elsa without a custom domain, but it is not covered by this tutorial.

Step 4: Setting up Travis CI

If you have never used Travis CI before, head in there and log in with your GitHub account. If your GitHub repo is private, you have to use the paid version on travis-ci.com, otherwise use travis-ci.org for free. This tutorial assumes your repo is public and will use travis-ci.org.

Go to your profile page and enable Travis CI for your repository.

Create a .travis.yml file in the repository with the following content:

language: python
python:
- 3.6
script:
- python website.py freeze
deploy:
  provider: script
  skip_cleanup: true
  script: python website.py deploy --no-freeze --push
  on:
    branch: master
    repo: username/reponame

Change username/reponame for your own repository slug, for example anna/mywebsite. Also change all occurrences of website.py with your own filename if named differently.

This file tells Travis CI what to do. Let's describe it a little bit more so you know what it does. If you are familiar enough with Travis CI, feel free to skip this part (ended by the first horizontal rule). If you want to know more about .travis.yml, read the documentation.

language: python
python:
- 3.6

This part makes sure we'll have Python 3.6 available on Travis CI. Travis CI allows to run different version of Python at the same time, but that would bring us no benefit in this situation. Elsa currently supports both Python 3.5 and Python 3.6, so we'll use the never version, but 3.5 would be fine as well.

script:
- python website.py freeze

The script section tells Travis CI what to run. This section will be run from all branches and also Pull Requests, so we let elsa freeze the website to see if it works. If it does not, Travis will indicate that in the Pull Request or next to a commit message in the list of commits on GitHub. You'll also get notified by e-mail.

deploy:
  provider: script
  skip_cleanup: true
  script: python website.py deploy --no-freeze --push
  on:
    branch: master
    repo: username/reponame

The deploy section is only run when the script section succeeds. We also limit it to master branch and your own repo to make sure only the right version of the website gets deployed. The skip_cleanup tells Travis CI not to clean the repository before deploying, so we can use the --no-freeze flag (Elsa already froze the website in the script section).

We've not used the python website.py deploy command in this tutorial yet, but you could run it locally to deploy your site as well. It pushes the frozen website to gh-pages branch of your repo, thus publishing it on GitHub pages.

On your own machine, you can push to the repository as usual, but Travis CI cannot, it does not have write access. In order to provide one, you'll have to create a personal access token on GitHub (repo scope needed) and provide it to Travis CI.

You cannot just add the token to .travis.yml, as anyone could read it, so you'll add it encrypted. Don't worry, it's not complicated, the easiest way is to use the travis command line tool that can be installed by gem install travis:

travis encrypt GITHUB_TOKEN=YOUR_TOKEN_GOES_HERE --add

Travis CI will not decrypt the token when running on different repositories (for example forks) or when running on Pull Requests. If you want to know more, read the documentation about encrypted environment variables.

The .travis.yml should now look similarly to this:

language: python
python:
- 3.6
script:
- python website.py freeze
deploy:
  provider: script
  skip_cleanup: true
  script: python website.py deploy --no-freeze --push
  on:
    branch: master
    repo: username/reponame
env:
  global:
    secure: IvsctOgRA/...snip.../moJ5qM=

On your machine you've installed elsa. You need to get it installed on Travis CI as well. To do that, add elsa to a file called requirements.txt in the root directory of your repository:

elsa

If you happen to have more dependencies, add them on separate lines. You don't need to add Flask, because elsa already depends on it, but if you add it, it will work as well.

Now you can push to the master branch. Note that at least the following files should be in git, but it is not necessary to push them all at once:

  • website.py (or your equivalent) and any other files needed for your Flask app
  • requirements.txt with elsa in it
  • .travis.yml

When you push, you can go to https://travis-ci.org/username/reponame (replacing the username and reponame with your own) to see how the build goes. If everything goes right, your website should be alive on your domain. And it will be updated anytime you push changes to the master branch.

Feel free to open an issue if something goes wrong or if you have questions.