# Snapcraft Guide (Linux)

This guide provides information on how to package your Electron application
for any Snapcraft environment, including the Ubuntu Software Center.

## Background and Requirements

Together with the broader Linux community, Canonical aims to fix many of the
common software installation problems with the [`snapcraft`](https://snapcraft.io/)
project. Snaps are containerized software packages that include required
dependencies, auto-update, and work on all major Linux distributions without
system modification.

There are three ways to create a `.snap` file:

1) Using [Electron Forge][electron-forge] or
   [`electron-builder`][electron-builder], both tools that come with `snap`
   support out of the box. This is the easiest option.
2) Using `electron-installer-snap`, which takes `electron-packager`'s output.
3) Using an already created `.deb` package.

In some cases, you will need to have the `snapcraft` tool installed.
Instructions to install `snapcraft` for your particular distribution are
available [here](https://snapcraft.io/docs/installing-snapcraft).

## Using `electron-installer-snap`

The module works like [`electron-winstaller`][electron-winstaller] and similar
modules in that its scope is limited to building snap packages. You can install
it with:

```sh
npm install --save-dev electron-installer-snap
```

### Step 1: Package Your Electron Application

Package the application using [electron-packager][electron-packager] (or a
similar tool). Make sure to remove `node_modules` that you don't need in your
final application, since any module you don't actually need will increase
your application's size.

The output should look roughly like this:

```plaintext
.
└── dist
    └── app-linux-x64
        ├── LICENSE
        ├── LICENSES.chromium.html
        ├── content_shell.pak
        ├── app
        ├── icudtl.dat
        ├── libgcrypt.so.11
        ├── libnode.so
        ├── locales
        ├── resources
        ├── v8_context_snapshot.bin
        └── version
```

### Step 2: Running `electron-installer-snap`

From a terminal that has `snapcraft` in its `PATH`, run `electron-installer-snap`
with the only required parameter `--src`, which is the location of your packaged
Electron application created in the first step.

```sh
npx electron-installer-snap --src=out/myappname-linux-x64
```

If you have an existing build pipeline, you can use `electron-installer-snap`
programmatically. For more information, see the [Snapcraft API docs][snapcraft-syntax].

```js @ts-nocheck
const snap = require('electron-installer-snap')

snap(options)
  .then(snapPath => console.log(`Created snap at ${snapPath}!`))
```

## Using `snapcraft` with `electron-packager`

### Step 1: Create Sample Snapcraft Project

Create your project directory and add the following to `snap/snapcraft.yaml`:

```yaml
name: electron-packager-hello-world
version: '0.1'
summary: Hello World Electron app
description: |
  Simple Hello World Electron app as an example
base: core22
confinement: strict
grade: stable

apps:
  electron-packager-hello-world:
    command: electron-quick-start/electron-quick-start --no-sandbox
    extensions: [gnome]
    plugs:
    - browser-support
    - network
    - network-bind
    environment:
      # Correct the TMPDIR path for Chromium Framework/Electron to ensure
      # libappindicator has readable resources.
      TMPDIR: $XDG_RUNTIME_DIR

parts:
  electron-quick-start:
    plugin: nil
    source: https://github.com/electron/electron-quick-start.git
    override-build: |
        npm install electron electron-packager
        npx electron-packager . --overwrite --platform=linux --output=release-build --prune=true
        cp -rv ./electron-quick-start-linux-* $SNAPCRAFT_PART_INSTALL/electron-quick-start
    build-snaps:
    - node/14/stable
    build-packages:
    - unzip
    stage-packages:
    - libnss3
    - libnspr4
```

If you want to apply this example to an existing project:

- Replace `source: https://github.com/electron/electron-quick-start.git` with `source: .`.
- Replace all instances of `electron-quick-start` with your project's name.

### Step 2: Build the snap

```sh
$ snapcraft

<output snipped>
Snapped electron-packager-hello-world_0.1_amd64.snap
```

### Step 3: Install the snap

```sh
sudo snap install electron-packager-hello-world_0.1_amd64.snap --dangerous
```

### Step 4: Run the snap

```sh
electron-packager-hello-world
```

## Using an Existing Debian Package

Snapcraft is capable of taking an existing `.deb` file and turning it into
a `.snap` file. The creation of a snap is configured using a `snapcraft.yaml`
file that describes the sources, dependencies, description, and other core
building blocks.

### Step 1: Create a Debian Package

If you do not already have a `.deb` package, using `electron-installer-snap`
might be an easier path to create snap packages. However, multiple solutions
for creating Debian packages exist, including [Electron Forge][electron-forge],
[`electron-builder`][electron-builder] or
[`electron-installer-debian`][electron-installer-debian].

### Step 2: Create a snapcraft.yaml

For more information on the available configuration options, see the
[documentation on the snapcraft syntax][snapcraft-syntax].
Let's look at an example:

```yaml
name: myApp
version: '2.0.0'
summary: A little description for the app.
description: |
 You know what? This app is amazing! It does all the things
 for you. Some say it keeps you young, maybe even happy.

grade: stable
confinement: classic

parts:
  slack:
    plugin: dump
    source: my-deb.deb
    source-type: deb
    after:
      - desktop-gtk3
    stage-packages:
      - libasound2
      - libnotify4
      - libnspr4
      - libnss3
      - libpcre3
      - libpulse0
      - libxss1
      - libxtst6
  electron-launch:
    plugin: dump
    source: files/
    prepare: |
      chmod +x bin/electron-launch

apps:
  myApp:
    command: bin/electron-launch $SNAP/usr/lib/myApp/myApp
    desktop: usr/share/applications/myApp.desktop
    # Correct the TMPDIR path for Chromium Framework/Electron to ensure
    # libappindicator has readable resources.
    environment:
      TMPDIR: $XDG_RUNTIME_DIR
```

As you can see, the `snapcraft.yaml` instructs the system to launch a file
called `electron-launch`. In this example, it passes information on to the
app's binary:

```sh
#!/bin/sh

exec "$@" --executed-from="$(pwd)" --pid=$$ > /dev/null 2>&1 &
```

Alternatively, if you're building your `snap` with `strict` confinement, you
can use the `desktop-launch` command:

```yaml
apps:
  myApp:
    # Correct the TMPDIR path for Chromium Framework/Electron to ensure
    # libappindicator has readable resources.
    command: env TMPDIR=$XDG_RUNTIME_DIR PATH=/usr/local/bin:${PATH} ${SNAP}/bin/desktop-launch $SNAP/myApp/desktop
    desktop: usr/share/applications/desktop.desktop
```

## Optional: Enabling desktop capture

Capturing the desktop requires PipeWire library in some Linux configurations that use
the Wayland protocol. To bundle PipeWire with your application, ensure that the base
snap is set to `core22` or newer. Next, create a part called `pipewire` and add it to
the `after` section of your application:

```yaml
  pipewire:
    plugin: nil
    build-packages: [libpipewire-0.3-dev]
    stage-packages: [pipewire]
    prime:
      - usr/lib/*/pipewire-*
      - usr/lib/*/spa-*
      - usr/lib/*/libpipewire*.so*
      - usr/share/pipewire
```

Finally, configure your application's environment for PipeWire:

```yaml
    environment:
      SPA_PLUGIN_DIR: $SNAP/usr/lib/$CRAFT_ARCH_TRIPLET/spa-0.2
      PIPEWIRE_CONFIG_NAME: $SNAP/usr/share/pipewire/pipewire.conf
      PIPEWIRE_MODULE_DIR: $SNAP/usr/lib/$CRAFT_ARCH_TRIPLET/pipewire-0.3
```

[snapcraft-syntax]: https://docs.snapcraft.io/build-snaps/syntax
[electron-packager]: https://github.com/electron/electron-packager
[electron-forge]: https://github.com/electron/forge
[electron-builder]: https://github.com/electron-userland/electron-builder
[electron-installer-debian]: https://github.com/electron-userland/electron-installer-debian
[electron-winstaller]: https://github.com/electron/windows-installer
