Setting up Debian for Gitian building

In this section we will be setting up the Debian 12 installation for Gitian building. We assume that a user gitianuser with sudo privileges was previously added.

First we need to set up dependencies. Type/paste the following in the terminal:

bash sudo apt-get install git ruby apt-cacher-ng qemu-utils debootstrap lxc python3-cheetah parted kpartx bridge-utils make debian-ports-archive-keyring debian-keyring curl firewalld apparmor iptables

Find the device name of your network card. You can list your connections with

bash ip address

Examples: eth0, eno1, ... Save it to the NET_DEV variable:

bash sudo -s NET_DEV=<your device name>

Then set up LXC and the rest with the following, which is a complex jumble of settings and workarounds:

```bash

the version of lxc-start in Debian needs to run as root, so make sure

that the build script can execute it without providing a password

echo "%sudo ALL=NOPASSWD: /usr/bin/lxc-start" > /etc/sudoers.d/gitian-lxc echo "%sudo ALL=NOPASSWD: /usr/bin/lxc-execute" >> /etc/sudoers.d/gitian-lxc

make /etc/rc.local script that sets up bridge between guest and host

echo '#!/bin/sh -e' > /etc/rc.local echo 'brctl addbr br0' >> /etc/rc.local echo 'ip addr add 10.0.3.1/24 broadcast 10.0.3.255 dev br0' >> /etc/rc.local echo 'ip link set br0 up' >> /etc/rc.local echo 'firewall-cmd --zone=trusted --add-interface=br0' >> /etc/rc.local echo "iptables -t nat -A POSTROUTING -o ${NET_DEV} -j MASQUERADE" >> /etc/rc.local echo 'echo 1 > /proc/sys/net/ipv4/ip_forward' >> /etc/rc.local echo 'exit 0' >> /etc/rc.local chmod +x /etc/rc.local

make sure that USE_LXC is always set when logging in as gitianuser,

and configure LXC IP addresses

echo 'export USE_LXC=1' >> /home/gitianuser/.profile echo 'export GITIAN_HOST_IP=10.0.3.1' >> /home/gitianuser/.profile echo 'export LXC_GUEST_IP=10.0.3.5' >> /home/gitianuser/.profile reboot ```

At the end Debian is rebooted to make sure that the changes take effect. The steps in this section only need to be performed once.

Note: When sudo asks for a password, enter the password for the user gitianuser not for root.

Installing Gitian

Re-login as the user gitianuser that was created during installation. The rest of the steps in this guide will be performed as that user.

Clone the git repositories for Bitcoin Cash Node and copy gitian-builder up to the top level.

bash git clone https://gitlab.com/bitcoin-cash-node/bitcoin-cash-node.git cp -fpra bitcoin-cash-node/contrib/gitian-builder .

Setting up the Gitian image

Gitian needs a virtual image of the operating system to build in. Currently this is Ubuntu 22.04 Jammy x86_64. This image will be copied and used every time that a build is started to make sure that the build is deterministic. Creating the image will take a while, but only has to be done once.

Execute the following as user gitianuser:

bash cd gitian-builder bin/make-base-vm --lxc --arch amd64 --distro ubuntu --suite jammy

There will be a lot of warnings printed during the build of the image. These can be ignored.

Note: When sudo asks for a password, enter the password for the user gitianuser not for root.

Downloading dependencies

Gitian may have problems connecting to the internet, which can make the build flaky. In order to avoid this, it is possible to download dependencies ahead of time.

Execute the following as user gitianuser:

bash cd gitian-builder make -C ../bitcoin-cash-node/depends download SOURCES_PATH=`pwd`/cache/common

Resuming the setup

Return to the main Gitian building document and continue at the (optional) steps for installing the MacOS SDK.