Installation.md

May 23, 2026 · View on GitHub

Security

Running a Lean instance on a server is always a potential security risk.

Therefore, this project uses Bubblewrap to run the instance in a container.

You can avoid using bubblewrap by using development mode or by providing NO_BWRAP=true to production mode. In that case, the Lean server will run without any container on your server.

Legal information

Depending on the GDPR and laws applying to your server, you will need to provide the following information:

client/config/config.tsx, serverCountry: where your server is located.
client/config/config.tsx, contactDetails: used in privacy policy & impressum
client/config/config.tsx, impressum: further legal notes

if contactDetails or impressum are not null, you will see an item Impressum in the dropdown menu containing that information.

Further, you might need to add the impressum manually to index.html for people with javascript disabled!

Build Instructions

The project is initially designed to run on Ubuntu 22 LTS.

Other OS or distributions have not been tested. PRs to the repo to improve the installation on other distributions are always welcome!

Prerequisites

On a running system, you might already have these installed, if not:

Install NPM: official instructions
Install Git: sudo apt-get install git
(optional) Install Bubblewrap: sudo apt-get install bubblewrap

Installation

Clone this repo:
```
git clone --recurse-submodules https://github.com/leanprover-community/lean4web.git
```
note that --recurse-submodules is needed to load the predefined projects in Projects/. (on an existing clone, you can call git submodule init and git submodule update)
Navigate into the cloned repository
```
cd lean4web
```
Install dependencies
```
npm install
```

Development mode

Start the project in development mode
```
npm start
```
Go to http://localhost:3000

Production mode

Compile the project
```
npm run build
```
Start the server
```
npm run prod
```
To disable the bubblewrap containers, start the server with
```
NO_BWRAP=true npm run prod
```
Start the client seperately, for example with
```
npm run start:client
```
and open http://localhost:3000

To set the locations of SSL certificates, use the following environment variables:

SSL_CRT_FILE=/path/to/crt_file.cer SSL_KEY_FILE=/path/to/private_ssl_key.pem npm run prod

name	values	default	description
`VITE_COLLAB`	`true`, `false`	`true`	Enable the collaboration feature

Server

For example for npm start, npm run production, npm run start:server.

name	values	default	description
`NO_BWRAP`	`true`, `false`	`false`	to disable to use of `bubblewrap` in production mode. This means `Lean` runs without any container on your system, which imposes a security risk!
`VITE_COLLAB`	`true`, `false`	`true`	Enable the collaboration feature
`GITHUB_ACTIONS`	`true` ,`false`	`false`	is set by github actions to change the verbosity of some server output
`NODE_ENV`	`development`, `production`
`PROJECTS_BASE_PATH`	string	`Projects`	relative path from the root of this repo to the folder where the Lean projects are located.
`PORT`	number	`8080` or `443`	sets the port for the backend server
`SSL_CRT_FILE`	string	`""`	recuired to serve https
`SSL_KEY_FILE`	string	`""`	recuired to serve https

Others

See Server Maintenance Notes.