How to install Lemmy from Scratch (Ubuntu 22.04 LTS)

The following tutorial provides step-by-step instructions to install Lemmy, a link aggregator for the fediverse, on Ubuntu 22.04. It includes the installation of Lemmy backend, Lemmy UI (web frontend), and the configuration of a reverse proxy with TLS using Nginx.

You should be able to install Lemmy without any errors. If you have any, please let me know. I intend to extend this tutorial to Lemmy upgrades, migration and deletion, and thus update the official documentation.

Installation

Lemmy Backend

Install Rust by following the instructions on Rustup.

Install the dependencies required for image hosting with Pict-rs:

apt install ffmpeg exiftool libgexiv2-dev --no-install-recommends
wget https://download.imagemagick.org/ImageMagick/download/binaries/magick
sha256sum magick  # Compare hash with the "message digest" on the official page
mv magick /usr/bin/
chmod 755 /usr/bin/magick

Compile and install Lemmy, and set up the database:

apt install pkg-config libssl-dev libpq-dev postgresql-15 postgresql-contrib-15 protobuf-compiler

# Install the latest release. You can specify a version with --version.
# The --locked argument uses the exact versions of dependencies specified in `cargo.lock` at release time.
# Running it without the flag will use newer minor release versions of those dependencies, which are not always guaranteed to compile.
# Remove the parameter `--features embed-pictrs` if you don't require image hosting.
cargo install lemmy_server --root /usr/ --locked --features embed-pictrs

# Replace db-passwd with a randomly generated password
sudo -iu postgres psql -c "CREATE USER lemmy WITH PASSWORD 'db-passwd';"
sudo -iu postgres psql -c "CREATE DATABASE lemmy WITH OWNER lemmy;"
sudo -iu postgres psql -c "ALTER USER lemmy WITH SUPERUSER;"

adduser lemmy --system --disabled-login --no-create-home --group

Configure the Lemmy backend by creating the minimal Lemmy config file at /etc/lemmy/lemmy.hjson

# Put your db-passwd from above
{
  database: {
    password: "db-passwd"
  },
  # Replace with your domain
  hostname: "example.com",
  bind: "127.0.0.1",
  federation: {
    enabled: true
  },
  # Remove this block if you don't require image hosting
  pictrs: {
    url: "http://localhost:8080/"
  }
}

Run chown lemmy:lemmy /etc/lemmy/ -R to set the correct owner.

Create a systemd unit file for Lemmy to automatically start and stop:

# Create /etc/systemd/system/lemmy.service
[Unit]
Description=Lemmy - A link aggregator for the fediverse
After=network.target

[Service]
User=lemmy
ExecStart=/usr/bin/lemmy_server
Environment=LEMMY_CONFIG_LOCATION=/etc/lemmy/lemmy.hjson
# Remove these two lines if you don't need Pict-rs
Environment=PICTRS_PATH=/var/lib/pictrs
Environment=PICTRS_ADDR=127.0.0.1:8080
Restart=on-failure

# Hardening
ProtectSystem=yes
PrivateTmp=true
MemoryDenyWriteExecute=true
NoNewPrivileges=true

[Install]
WantedBy=multi-user.target

Run systemctl enable lemmy and systemctl start lemmy to enable and start the service.

Verify the Lemmy installation by checking the logs:
```
journalctl -u lemmy
```
The logs should show “Starting http server at 127.0.0.1:8536”. You can also run curl localhost:8536/api/{version}/site to check the response.
For Pict-rs, run curl 127.0.0.1:8080 and ensure that it outputs nothing, particularly no errors.

Install Lemmy UI (Web Frontend)

Install dependencies:

# Install Node.js and Yarn from external repositories
curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
curl -fsSL https://deb.nodesource.com/setup_14.x | sudo -E bash -
sudo apt install nodejs yarn

Clone the Lemmy UI Git repository, checkout the desired version, and compile it:

mkdir /var/lib/lemmy-ui
cd /var/lib/lemmy-ui
chown lemmy:lemmy .
sudo -u lemmy bash
git clone https://github.com/LemmyNet/lemmy-ui.git --recursive .
git checkout 0.17.4  # Replace with the version you want to install
yarn install --pure-lockfile
yarn build:prod
exit

Create a systemd unit file for Lemmy UI:

# Create /etc/systemd/system/lemmy-ui.service
[Unit]
Description=Lemmy UI - Web frontend for Lemmy
After=lemmy.service
Before=nginx.service

[Service]
User=lemmy
WorkingDirectory=/var/lib/lemmy-ui
ExecStart=/usr/bin/node dist/js/server.js
Environment=LEMMY_INTERNAL_HOST=localhost:8536
Environment=LEMMY_EXTERNAL_HOST=example.com
Environment=LEMMY_HTTPS=true
Restart=on-failure

# Hardening
ProtectSystem=full
PrivateTmp=true
NoNewPrivileges=true

[Install]
WantedBy=multi-user.target

Run systemctl enable lemmy-ui and systemctl start lemmy-ui to enable and start the service.

Verify the Lemmy UI installation by running curl -I localhost:1234 and checking for a 200 OK response.

Configure Reverse Proxy and TLS

Install Nginx and Certbot:

apt install nginx certbot python3-certbot-nginx

Request a Let’s Encrypt TLS certificate:
```
certbot certonly --nginx
```
Follow the instructions provided by Certbot to complete the process.
Set up automatic certificate renewal by adding a crontab entry:
```
sudo crontab -e
```
Add the following line, replacing example.com with your actual domain:
```
@daily certbot certonly --nginx --cert-name example.com -d example.com --deploy-hook 'nginx -s reload'
```

Download the Nginx configuration file for Lemmy:

curl https://raw.githubusercontent.com/LemmyNet/lemmy-ansible/main/templates/nginx.conf \
    --output /etc/nginx/sites-enabled/lemmy.conf

Replace the variables in the Nginx configuration file:

sed -i -e 's/{{domain}}/example.com/g' /etc/nginx/sites-enabled/lemmy.conf
sed -i -e 's/{{lemmy_port}}/8536/g' /etc/nginx/sites-enabled/lemmy.conf
sed -i -e 's/{{lemmy_ui_port}}/1234/g' /etc/nginx/sites-enabled/lemmy.conf

Reload the Nginx configuration:
```
nginx -s reload
```
Open your Lemmy domain in the browser. It should display a configuration screen. Use this screen to create the first admin user and the default community.