reiallenramos/gogovsg

The official link shortener of the Singapore government

GoGovSG

The official Singapore government link shortener.

Content

• GoGovSG
  • Content
  • Introduction
  • Getting Started
    • Running Locally
    • Setting up the infrastructure
    • Deploying
  • Pre-release
  • Documentation
    • Folder Structure
    • Babel
    • ESLint
    • Webpack
    • Webpack dev server
    • Nodemon
    • Express
    • Concurrently
    • VSCode + ESLint

Introduction

Go.gov.sg is the official Singapore government link shortener, built by the Open Government Products team in GovTech.

There are multiple reasons why we built an official government link shortener:

• URLs are too long to fit into tweets or SMSes, and difficult to remember
• Email clients might block other commercial link shorteners if they are listed as spam on their site
• Citizens are afraid of phishing when receiving a shortened link and unsure of where it goes

With Go.gov.sg, citizens are safe in the knowledge that the links are official and safe. Any public officer can log in with their government emails and immediately create short links with the official gov.sg domain.

Getting Started

Start by cloning the repository and installing dependencies.

# Clone the repository
git clone [email protected]:opengovsg/GoGovSG.git gogovsg

# Go inside the directory
cd gogovsg

# Install dependencies
npm install

Running Locally

Make sure you have docker-compose version >= 1.23.1 and Docker version >= 18.09.0 installed. Then run:

npm run dev

Docker-compose will spin up a postgresql database and redis container to be connected to the backend server. Once the setup is complete, the local version of GoGovSG can be accessed on your browser via localhost:3000. Note that 3000 is the port number that the webpack dev server listens on; the backend server actually listens on port 8080 instead.

Because redirects are served directly from the backend, shortlinks should be accessed via localhost:8080/shortlink and not localhost:3000/shortlink. Also, given that GoGovSG will attempt to send emails directly from your computer when running on localhost, there is a chance that the email might land in spam or not be sent entirely. To mitigate this, we have set the one-time password for all log-in attempts on localhost to be 111111.

Setting up the infrastructure

Much of this step will involve setting up key infrastructure components since we do not have docker-compose to do that for us. On top of running the server, GoGovSG minimally requires the following infrastructure to be available:

• A PostgreSQL database (for storing short-long URL mappings)
• A Redis server (transient storage of sessions, one-time passwords, click statistics and frequently used shortlinks)

After these have been set up, set the environment variables according to the table below:

Environment Variable	Required	Description/Value
NODE_ENV	Yes	production
DB_URI	Yes	The postgres connection string, e.g. postgres://postgres:postgres@postgres:5432/postgres
OG_URL	Yes	The origin url, used for both google analytics and circular-redirect prevention. E.g. https://go.gov.sg
REDIS_OTP_URI	Yes	Redis connection string, e.g. redis://redis:6379/0
REDIS_SESSION_URI	Yes	Redis connection string, e.g. redis://redis:6379/1
REDIS_REDIRECT_URI	Yes	Redis connection string, e.g. redis://redis:6379/2
REDIS_STAT_URI	Yes	Redis connection string, e.g. redis://redis:6379/3
SESSION_SECRET	Yes	For hashing browser sessions, e.g. change-this
VALID_EMAIL_GLOB_EXPRESSION	Yes	The glob expression used to test if a provided email address is valid. For safety, we have disabled the use of negations, ext-glob, glob stars (**) and braces, e.g. *@youremaildomain.com
GA_TRACKING_ID	No	The Google Analytics tracking ID, e.g. UA-12345678-9
SENTRY_AUTH_TOKEN	No	To get relevant permissions to upload the source maps.
SENTRY_DNS	No	The Sentry DNS used for bug and error tracking. e.g. https://[email protected]/12345
SENTRY_ORG	No	Our Sentry organisation name, e.g. example-org
SENTRY_PROJECT	No	The relevant Sentry project. e.g. project-prod
SENTRY_URL	No	The Sentry url. e.g. https://sentry.io/
LOGIN_MESSAGE	No	A text message that will be displayed on the login page as a snackbar.

Trigger the typescript compilation and webpack bundling process by calling npm run build.

Finally, start the production server by running npm start.

Deploying

GoGovSG uses Travis to deploy to AWS Elastic Beanstalk. We also use Sentry.io to track client-side errors.

Environment Variable	Required	Description/Value
AWS_ACCESS_KEY_ID	Yes	AWS credential ID used to deploy to Elastic Beanstalk
AWS_SECRET_ACCESS_KEY	Yes	AWS credential secret used to deploy to Elastic Beanstalk
AWS_EB_ENV_PRODUCTION, AWS_EB_ENV_STAGING	Yes	Elastic Beanstalk environment name
AWS_EB_APP_PRODUCTION, AWS_EB_APP_STAGING	Yes	Elastic Beanstalk application name
AWS_EB_BUCKET_PRODUCTION, AWS_EB_BUCKET_STAGING	Yes	S3 bucket used to store the application bundle
AWS_EB_REGION	Yes	AWS region to deploy to, e.g. ap-southeast-1
EMAIL_RECIPIENT	Yes	Email for Travis notifications
PRODUCTION_BRANCH, STAGING_BRANCH	Yes	Name of Git branches for triggerring deployments to production/staging respectively
REPO	Yes	Docker container registry URI to push built images to
SENTRY_ORG	No	Sentry.io organisation name
SENTRY_PROJECT	No	Sentry.io project name
SENTRY_URL	No	Sentry.io URL e.g. https://sentry.io/
SENTRY_DNS	No	Sentry.io endpoint to post client-side errors to

Pre-release

We have yet to setup travis to automate these steps:

• Update package version
• Update credits opengovsg/credits-generator
• Upload pdf to S3 bucket

Documentation

Folder Structure

All source code resides in the src directory. Inside src, there is client and server directory. Frontend code (react, css, js and other assets) will be in client directory. Backend Node.js/Express code will be in the server directory.

Babel

Babel helps us to write code in the latest version of JavaScript. If an environment does not support certain features natively, Babel will help us to compile those features down to a supported version. It also helps us to convert JSX to Javascript. .babelrc file is used describe the configurations required for Babel. Below is the .babelrc file which I am using.

{
    "presets": ["env", "react"]
}

Babel requires plugins to do the transformation. Presets are the set of plugins defined by Babel. Preset env allows to use babel-preset-es2015, babel-preset-es2016, and babel-preset-es2017 and it will transform them to ES5. Preset react allows us to use JSX syntax and it will transform JSX to Javascript.

ESLint

ESLint is a pluggable and configurable linter tool for identifying and reporting on patterns in JavaScript.

.eslintrc.json file (alternatively configurations can we written in Javascript or YAML as well) is used describe the configurations required for ESLint.

I am using Airbnb's Javascript Style Guide which is used by many JavaScript developers worldwide. Since we are going to write both client (browser) and server side (Node.js) code, I am setting the env to browser and node. Optionally, we can override the Airbnb's configurations to suit our needs. I have turned off no-console, comma-dangle and react/jsx-filename-extension rules.

Webpack

Webpack is a module bundler. Its main purpose is to bundle JavaScript files for usage in a browser.

webpack.config.js file is used to describe the configurations required for webpack.

1. entry: entry: ./src/client/index.js is where the application starts executing and webpack starts bundling. Note: babel-polyfill is added to support async/await. Read more here.
2. output path and filename: the target directory and the filename for the bundled output
3. module loaders: Module loaders are transformations that are applied on the source code of a module. We pass all the js file through babel-loader to transform JSX to Javascript. CSS files are passed through css-loaders and style-loaders to load and bundle CSS files. Fonts and images are loaded through url-loader.
4. Dev Server: Configurations for the webpack-dev-server which will be described in coming section.
5. plugins: clean-webpack-plugin is a webpack plugin to remove the build folder(s) before building. html-webpack-plugin simplifies creation of HTML files to serve your webpack bundles. It loads the template (public/index.html) and injects the output bundle.

Webpack dev server

Webpack dev server is used along with webpack. It provides a development server that provides live reloading for the client side code. This should be used for development only.

The devServer section of webpack.config.js contains the configuration required to run webpack-dev-server which is given below.

devServer: {
    port: 3000,
    open: true,
    proxy: {
        "/api": "http://localhost:8080"
    }
}

Port specifies the Webpack dev server to listen on this particular port (3000 in this case). When open is set to true, it will automatically open the home page on startup. Proxying URLs can be useful when we have a separate API backend development server and we want to send API requests on the same domain. In our case, we have a Node.js/Express backend where we want to send the API requests to.

Nodemon

Nodemon is a utility that will monitor for any changes in the server source code and it automatically restart the server. This is used in development only.

nodemon.json file is used to describe the configurations for Nodemon.

{
  "watch": ["src/server/"]
}

Here, we tell nodemon to watch the files in the directory src/server where out server side code resides. Nodemon will restart the node server whenever a file under src/server directory is modified.

Express

Express is a web application framework for Node.js. It is used to build our backend API's.

src/server/index.js is the entry point to the server application. This starts a server and listens on port 8080 for connections. It is also configured to serve the static files from dist directory.

Concurrently

Concurrently is used to run multiple commands concurrently. I am using it to run the webpack dev server and the backend node server concurrently in the development environment. Below are the npm/yarn script commands used.

"client": "webpack-dev-server --mode development --devtool inline-source-map --hot",
"server": "nodemon src/server/index.js",
"dev": "concurrently \"npm run server\" \"npm run client\""

VSCode + ESLint

VSCode is a lightweight but powerful source code editor. ESLint takes care of the code-quality.