Gitian buids for bitcoin-like blockchains.md

Using gitian to create multi-OS, multi-arch builds of bitcoin-like blockchains

Warning

This steps in this guide will leave your machine highly insecure. Hence, the guide should be used on a temporary VPS not an actual machine/server.

Setting up Ubuntu for gitian building

In this section we will be setting up the Ubuntu installation for Gitian building. We are using the user builder to do the setup. You can use any non-root user.

First we need to log in as root to set up dependencies and make sure that our user can use the sudo command. Type/paste the following in the terminal:

apt-get install make git ruby sudo apt-cacher-ng qemu-utils debootstrap lxc python-cheetah parted kpartx bridge-utils python-vm-builder
adduser builder sudo

When you get a colorful screen with a question about the 'LXC directory', just go with the default (/var/lib/lxc).

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

# lxc-start in Ubuntu needs to run as root, so make sure
# that the build script can exectute it without providing a password
echo "%sudo ALL=NOPASSWD: /usr/bin/lxc-start" > /etc/sudoers.d/builder

# also add the following line if you want to run the gitian-build.py
# script in the background using nohup.
# Note: it will give 'builder' a __password-less sudo__ capability
echo "builder ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers.d/builder

# add cgroup for LXC
echo "cgroup  /sys/fs/cgroup  cgroup  defaults  0   0" >> /etc/fstab

# 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 'ifconfig br0 10.0.3.2/24 up' >> /etc/rc.local
echo 'exit 0' >> /etc/rc.local

# make sure that USE_LXC is always set when logging in as gitian,
# and configure LXC IP addresses
echo 'export USE_LXC=1' >> /home/builder/.profile
echo 'export GITIAN_HOST_IP=10.0.3.2' >> /home/builder/.profile
echo 'export LXC_GUEST_IP=10.0.3.5' >> /home/builder/.profile
reboot

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

Running the gitian python script.

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

If you don't have one, create a GPG key. The script will stop if it doesn't find a key in your keychain.

gpg --gen-key

Copy the gitian-build.py script from your blockchain's /contrib/' directory to builder`'s home directory. Then, run

./gitian-build.py --setup "GPG Key Name" "1.0.0"

If you don't pass --commit (completely unrelated to the option --no-commit), the script will assume the version to be a tag and automaticall prepend v to it.

Create the dir inputs inside gitian-builder and copy MacOSX10.11.sdk.tar.gz to it. (See README_osx.md)

./gitian-build.py --build --jobs $(nproc) --os lwm --no-commit "GPG Key Name" "1.0.0"

The building phase of the gitian job is going to take an extremely long time because, by default binaries for the following architectures are built: "i686-pc-linux-gnu x86_64-linux-gnu arm-linux-gnueabihf aarch64-linux-gnu riscv64-linux-gnu". AFAIK, the only way to change this is remove hosts(archs) directly from the .yml file.

You can use nohup if you enabled password-less sudo in the previous step.

Lastly

Once the build is over, you should find all the packaged binaries in $HOME/blockchain-binaries/1.0.0/ diretory. scp that directory over to your machine and delete the VPS