# Build instructions for Linux

## Environment Setup

### Build dependencies

```
cd <multipass>
sudo apt install devscripts equivs
mk-build-deps -s sudo -i
```

If your local username contains `@`, `mk-build-deps` can generate an invalid
maintainer address and fail. In that case, set maintainer identity explicitly:

```
DEBEMAIL="you@example.com" DEBFULLNAME="Your Name" mk-build-deps -s sudo -i
```

To make this persistent, add `DEBEMAIL` and `DEBFULLNAME` to your shell profile
or `~/.devscripts`.

### Install the Rust compiler

1. Install the `rustup` snap:
```
sudo snap install rustup --classic
```
2. Install the stable version of the Rust toolchain:
```
rustup default stable
```

## Building

First, go into the repository root and get all the submodules:

```
cd <multipass>
git submodule update --init --recursive
```

If building on arm, s390x, ppc64le, or riscv, you will need to set the `VCPKG_FORCE_SYSTEM_BINARIES`  environment
variable:

```
export VCPKG_FORCE_SYSTEM_BINARIES=1
```

Then create a build directory and run CMake.

```
mkdir build
cd build
cmake ../
```

This will fetch all necessary content, build vcpkg dependencies, and initialize the build system. You can also specify
the `-DCMAKE_BUILD_TYPE` option to set the build type (e.g., `Debug`, `Release`, `Coverage`, etc.).

To use a different vcpkg, pass `-DMULTIPASS_VCPKG_LOCATION="path/to/vcpkg"` to CMake.
It should point to the root vcpkg location, where the top bootstrap scripts are located.

Finally, to build the project, run:

```
cmake --build . [--parallel <N>]
```

Tips:
- You may use `--parallel <N>` to speed up the build.
- However, make sure you have enough physical memory and swap space available before doing so (the build step has a very high memory footprint).
- You may install and use `earlyoom` to prevent your computer from freezing if you're reaching the limits.

Please note that if you're working on a forked repository that you created using the "Copy the main branch only" option,
the repository will not include the necessary git tags to determine the Multipass version during CMake configuration. In
this case, you need to manually fetch the tags from the upstream by running
`git fetch --tags https://github.com/canonical/multipass.git` in the `<multipass>` source code directory.

## Run the Multipass daemon and client

First, install Multipass's runtime dependencies. On AMD64 architecture, you can do this with:

```
sudo apt update
sudo apt install libgl1 libpng16-16 libxml2 dnsmasq-base \
    dnsmasq-utils qemu-utils libslang2 iproute2 iptables \
    iputils-ping libatm1 libxtables12 xterm
```

On ARM64 architecture, you can do this by running:

```
sudo apt update
sudo apt install libgl1 libpng16-16 libxml2 dnsmasq-base \
    dnsmasq-utils qemu-efi-aarch64 qemu-utils libslang2 \
    iproute2 iptables iputils-ping libatm1 libxtables12 \
    xterm
```

You will also need to install your CPU architecture's variant of `qemu-system`. For example, you will need

```
sudo apt install qemu-system-x86
```

on x86_64 machines.

Additionally, on ARM64 architecture, there is an extra step to set up the `QEMU_EFI.fd` file:

```
sudo cp /usr/share/qemu-efi-aarch64/QEMU_EFI.fd /usr/share/qemu/QEMU_EFI.fd
```

Then run the Multipass daemon:

```
pkexec <multipass>/build/bin/multipassd &
```

If you want the desktop integration to work for the locally built GUI, you can run `cmake` with `-DMULTIPASS_DESKTOP_INTEGRATION=ON`.
This will make the build process generate an appropriate `.desktop` file and move it to `~/.local/share/applications`.

Optionally, enable auto-complete in Bash:
```
source <multipass>/completions/bash/multipass
```

To be able to use the binaries without specifying their path:

```
export PATH=<multipass>/build/bin
```

Now you can use the `multipass` command from your terminal (for example
`<multipass>/build/bin/multipass launch --name foo`) or launch the GUI client with the command `<multipass>/build/bin/multipass.gui`.