/median

An experiment in zero-infrastructure charting.

Primary LanguageJavaScript

median

What is this?

An experiment in zero-infrastructure charting.

Assumptions

The following things are assumed to be true in this documentation.

  • You are running OSX.
  • You are using Python 2.7. (Probably the version that came OSX.)
  • You have virtualenv and virtualenvwrapper installed and working.
  • You have NPR's AWS credentials stored as environment variables locally.

For more details on the technology stack used with the app-template, see our development environment blog post.

What's in here?

The project contains the following folders and important files:

  • confs -- Server configuration files for nginx and uwsgi. Edit the templates then fab <ENV> servers.render_confs, don't edit anything in confs/rendered directly.
  • fabfile -- Fabric commands for automating setup, deployment, data processing, etc.
  • jst -- Javascript (Underscore.js) templates.
  • less -- LESS files, will be compiled to CSS and concatenated for deployment.
  • templates -- HTML (Jinja2) templates, to be compiled locally.
  • www -- Static and compiled assets to be deployed. (a.k.a. "the output")
  • app.py -- A Flask app for rendering the project locally.
  • app_config.py -- Global project configuration for scripts, deployment, etc.
  • crontab -- Cron jobs to be installed as part of the project.
  • public_app.py -- A Flask app for running server-side code.
  • render_utils.py -- Code supporting template rendering.
  • requirements.txt -- Python requirements.
  • static.py -- Static Flask views used in both app.py and public_app.py.

Bootstrap the project

Node.js is required for the static asset pipeline. If you don't already have it, get it like this:

brew install node
curl https://npmjs.org/install.sh | sh

Then bootstrap the project:

cd median
mkvirtualenv median
pip install -r requirements.txt
npm install
fab update

Problems installing requirements? You may need to run the pip command as ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-future pip install -r requirements.txt to work around an issue with OSX.

Hide project secrets

Project secrets should never be stored in app_config.py or anywhere else in the repository. They will be leaked to the client if you do. Instead, always store passwords, keys, etc. in environment variables and document that they are needed here in the README.

Any environment variable that starts with $PROJECT_SLUG_ will be automatically loaded when app_config.get_secrets() is called.

Adding a page to the site

A site can have any number of rendered pages, each with a corresponding template and view. To create a new one:

  • Add a template to the templates directory. Ensure it extends _base.html.
  • Add a corresponding view function to app.py. Decorate it with a route to the page name, i.e. @app.route('/filename.html')
  • By convention only views that end with .html and do not start with _ will automatically be rendered when you call fab render.

Run the project

A flask app is used to run the project locally. It will automatically recompile templates and assets on demand.

workon $PROJECT_SLUG
fab app

Visit localhost:8000 in your browser.

Compile static assets

Compile LESS to CSS, compile javascript templates to Javascript and minify all assets:

workon median
fab render

(This is done automatically whenever you deploy to S3.)

Test the rendered app

If you want to test the app once you've rendered it out, just use the Python webserver:

cd www
python -m SimpleHTTPServer

Deploy to S3

fab staging master deploy

Deploy to EC2

You can deploy to EC2 for a variety of reasons. We cover two cases: Running a dynamic web application (public_app.py) and executing cron jobs (crontab).

Servers capable of running the app can be setup using our servers project.

For running a Web application:

  • In app_config.py set DEPLOY_TO_SERVERS to True.
  • Also in app_config.py set DEPLOY_WEB_SERVICES to True.
  • Run fab staging master servers.setup to configure the server.
  • Run fab staging master deploy to deploy the app.

For running cron jobs:

  • In app_config.py set DEPLOY_TO_SERVERS to True.
  • Also in app_config.py, set INSTALL_CRONTAB to True
  • Run fab staging master servers.setup to configure the server.
  • Run fab staging master deploy to deploy the app.

You can configure your EC2 instance to both run Web services and execute cron jobs; just set both environment variables in the fabfile.

Install cron jobs

Cron jobs are defined in the file crontab. Each task should use the cron.sh shim to ensure the project's virtualenv is properly activated prior to execution. For example:

* * * * * ubuntu bash /home/ubuntu/apps/median/repository/cron.sh fab $DEPLOYMENT_TARGET cron_jobs.test

To install your crontab set INSTALL_CRONTAB to True in app_config.py. Cron jobs will be automatically installed each time you deploy to EC2.

The cron jobs themselves should be defined in fabfile/cron_jobs.py whenever possible.

Install web services

Web services are configured in the confs/ folder.

Running fab servers.setup will deploy your confs if you have set DEPLOY_TO_SERVERS and DEPLOY_WEB_SERVICES both to True at the top of app_config.py.

To check that these files are being properly rendered, you can render them locally and see the results in the confs/rendered/ directory.

fab servers.render_confs

You can also deploy only configuration files by running (normally this is invoked by deploy):

fab servers.deploy_confs

Run a remote fab command

Sometimes it makes sense to run a fabric command on the server, for instance, when you need to render using a production database. You can do this with the fabcast fabric command. For example:

fab staging master servers.fabcast:deploy

If any of the commands you run themselves require executing on the server, the server will SSH into itself to run them.