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Development Setup

These instructions covers three platforms: macOS 12, Ubuntu (22.04), and Windows 11 (WSL, with Ubuntu 22.04). Instructions for Ubuntu also apply to Windows (WSL), except where special instructions are noted.

Install and configure dependencies

Install third-party software

On macOS

We'll use Homebrew to fetch most of the packages on macOS:

  • libvips - brew install vips
  • nginx - brew install nginx. Start Nginx server after installation.
  • postgresql - Install and follow its instructions, including the part about setting up command-line tools.

Important: Make sure that you start Nginx after you install them. Instructions on how to do that will be printed to the command-line after it's successfully installed.

On Ubuntu

The following command should install all required dependencies on Ubuntu. If you're using another flavour of Linux, adapt the command to work with the package manager available with your distribution.

sudo apt-get install libvips postgresql postgresql-contrib autoconf libtool nginx libpq-dev

Install Ruby & Node.js

Use asdf to install Ruby and Node.js. Simply run asdf install from the project directory. It'll read the required versions from the .tool-versions file and install them.

Install Rubygems

Once Ruby is installed, fetch all gems using Bundler:

bundle install

You may need to install the bundler gem if the version of Ruby you have installed comes with a different bundler version. Simply follow the instructions in the error message, if this occurs.

On macOS, if installation of the pg gem crashes, asking for libpq-fe.h, run the following commands, and then run bundle install again:

# Find the exact path to pg_config.
find /Applications -name pg_config

# Use the path returned by the above command in the following one. Replace X.Y.Z with the same version that failed to install.
gem install pg -v 'X.Y.Z' -- --with-pg-config=/path/to/pg_config

Fetch JS & ReScript dependencies

  1. Install Yarn following offical instructions.
  2. From the root of the repository, run the yarn command to install all node modules; this will also install ReScript.

Set credentials for local database

Let's make sure that PostgreSQL server is up and running using the following command:

# macOS
brew services start postgresql

# Ubuntu
sudo service postgresql start

Note for WSL users: You'll need to run the above command each time you restart Windows, and open up Ubuntu for the first time.

If you're setting up Postgres for the first time, we'll now set a password for the postgres database username.

Once PostgreSQL server is running, we'll set a password for the default database user. Open the psql CLI:

# macOS
psql -U postgres

# Ubuntu
sudo -u postgres psql

Then, in the PostgreSQL CLI, set a new password and quit.

# Set a password for this username.
\password postgres

# Quit.

Configure application environment variables

  1. Copy example.env to .env.

    cp example.env .env
  2. Update the values of DB_USERNAME and DB_PASSWORD in the new .env file.

    Use the same values from the previous step. The username should be postgres, and the password will be whatever value you've set.

  3. Set up push notifications by generating and setting VAPID keys to enable push notifications:

    # In the Rails console...
    vapid_key = WebPush.generate_key

    # Save the printed string in your .env file.
    puts "VAPID_PUBLIC_KEY=#{vapid_key.public_key}\nVAPID_PRIVATE_KEY=#{vapid_key.private_key}"

    Paste the output into .env, replacing the existing lines for these two keys.

The .env file contains environment variables that are used to configure the application. The file contains documentation explaining where you should source its values from. If you're just starting out, you shouldn't have to change any variables other than the ones listed above.

Setup Overcommit

Overcommit adds automatic checks that prevents us from making silly mistakes when committing changes.

bundle exec overcommit --install
bundle exec overcommit --sign

Note: You may need to run asdf reshim to update paths, if you've just finished running Ruby's bundle install command.

Seed local database

bundle exec rails db:setup

This will also seed data into the database that will be useful for testing during development.

Compile ReScript code

If you've used the yarn command to install JS dependencies, then ReScript code should already be compiled at this point. To compile ReScript code again (if you've made changes), you can either do a one-time build, or set up a watcher:

# One-time compilation.
yarn run re:build

# Compile, and then watch for changes.
yarn run re:watch

Start the Rails server

bundle exec rails server

Run Vite dev server

Optional: Start the Vite development server with:

bin/vite dev

Keeping the Vite development server running makes working on the frontend much faster since it serves native JavaScript modules, avoiding a lengthy rebuild process.

With the Rails server running, visit the school using your browser at http://localhost:3000.

You should be able to sign in as (use the Continue as Developer option on the sign-in page), to test access to all interfaces. Test data has been seeded to the development database to make this process easier.

Test new features without the dev server running

All pages should work with or without bin/vite dev server running. If you're planning to change any JS code, leaving it running is the best option. However, we need to make sure that we manually test whether all pages function without the dev server running. This is because the dev server builds browser-native ESM with esbuild, but the full build process uses rollup.js. There are subtle differences in the way these two tools interact with old non-ESM JS packages. Use of newer JS packages should not cause any issues.

Debugging when not running the Vite dev server

If you encounter issues when running sans dev server, you can disable code obfuscation by setting build: { minify: false } in the vite.config.ts file.

Code formatting

If you're planning to edit the LMS's code and send pull requests, please make sure that your code is properly formatted.

We recommend using Visual Studio Code with the following extensions...

...with the following settings:

"editor.formatOnSave": true,
"editor.tabSize": 2,
"files.associations": {
"*.css": "tailwindcss"
"files.autoSave": "onFocusChange",
"files.insertFinalNewline": true,
"files.trimFinalNewlines": true,
"files.trimTrailingWhitespace": true,
"ruby.format": false,
"ruby.useLanguageServer": true,
"vscode-yaml-sort.quotingType": "\"",
"vscode-yaml-sort.useLeadingDashes": false,
"[css]": {
"editor.defaultFormatter": "esbenp.prettier-vscode"
"[erb]": {
"editor.defaultFormatter": "aliariff.vscode-erb-beautify"
"[html]": {
"editor.defaultFormatter": "esbenp.prettier-vscode"
"[javascript]": {
"editor.defaultFormatter": "esbenp.prettier-vscode"
"[jsonc]": {
"editor.defaultFormatter": "esbenp.prettier-vscode"
"[ruby]": {
"editor.defaultFormatter": "esbenp.prettier-vscode"

YAML files

When editing YAML files (especially translations) please use the YAML Sort extension to sort keys.


The version number for the LMS is stored in env.PF_VERSION in the .github/workflows/ci.yml file.

The version number must be bumped when a breaking change is introduced. A breaking change is classified as any change that a LMS instance maintainer should be aware of when upgrading. Such changes should also be documented in the Upgrading Guide.

Enabling multitenancy

Optional: If you'd like to enable multitenancy in your development environment, a few additional steps are required.

Add environment variables

  1. Turn on the multitenancy mode by additing the following environment variable.
  1. Update the SSO domain.

Set up a reverse-proxy using Nginx

Use Nginx to set up a reverse proxy on a .localhost domain to point it to your web application running on port 3000 (the default Rails server port). Use following server configuration as an example:

  1. Create a new Nginx server configuration file...

    • /opt/homebrew/etc/nginx/servers/pupilfirst (macOS)
    • /etc/nginx/sites-enabled/pupilfirst (Linux)

    ...and save the following configuration inside it:

    server {
    listen 80;
    server_name school.localhost;

    location / {
    proxy_pass http://localhost:3000/;
    proxy_set_header Host $host;
  2. Restart nginx so that it picks up the new configuration.

    # macOS
    brew services restart nginx

    # Ubuntu
    sudo service nginx restart

    On Debian/Ubuntu, NGINX comes with a sites-enabled/default file which may need to be removed before the LMS will begin responding to requests.

  3. You may also need to point the local school domain school.localhost, and the www and sso subdomains, to in the /etc/hosts file (on macOS and Ubuntu), and the C:\Windows\System32\Drivers\etc\hosts file on Windows:

    # Append to the /etc/hosts file. school.localhost

If your Nginx reverse-proxy has been set up correctly, then visit the school using your browser at http://school.localhost.

Set up schools and domains

Make sure that the domains table is populated with FQDNs that you're going to use locally, and that they are all linked to the correct schools table entry. These will be verified on each request; verification failure will cause a redirect to<UNVERIFIABLE_FQDN>. So if this happens to you, check your schools and domains table entries.