How to set up a test bench

This guide shows how to set up simple test bench that automatically test your code you’re about to push. It is written especially for core3 branch of core-admin.git repo, but some ideas are universal.

We will set up a spare machine (bare metal, not a virtual) that will be hosting our experimental Dom0. We will communicate with it via Ethernet and SSH. This tutorial assumes you are familiar with QubesBuilder and you have it set up and running flawlessly.

Notice: This setup intentionally weakens some security properties in the testing system. So make sure you understand the risks and use exclusively for testing.

Setting up the Machine

Install ISO

First, do a clean install from the .iso you built or grabbed elsewhere (for example here).

Enabling Network Access in Dom0

Internet access is intentionally disabled by default in dom0. But to ease the deployment process we will give it access. The following steps should be done in dom0.

Note: the following assume you have only one network card. If you have two, pick one and leave the other attached to sys-net.

  1. Remove the network card (PCI device) from sys-net
  2. Restart your computer (for the removal to take effect)
  3. Install dhcp-client and openssh-server on your testbench’s dom0.
  4. Save the following script in /home/user/bin/dom0_network.sh and make it executable. It should enable your network card in dom0. Be sure to adjust the script’s variables to suit your needs.

    #!/bin/sh
    
    # adjust this for your NIC (run lspci)
    BDF=0000:02:00.0
    
    # adjust this for your network driver
    DRIVER=e1000e
    
    prog=$(basename $0)
    
    pciunbind() {
        local path
        path=/sys/bus/pci/devices/${1}/driver/unbind
        if ! [ -w ${path} ]; then
            echo "${prog}: Device ${1} not bound"
            return 1
        fi
        echo -n ${1} >${path}
    }
    
    pcibind() {
        local path
        path=/sys/bus/pci/drivers/${2}/bind
        if ! [ -w ${path} ]; then
            echo "${prog}: Driver ${2} not found"
            return 1
        fi
        echo ${1} >${path}
    }
    
    pciunbind ${BDF}
    pcibind ${BDF} ${DRIVER}
        
    sleep 1
    dhclient
    
  5. Configure your DHCP server so your testbench gets static IP and connect your machine to your local network. You should ensure that your testbench can reach the Internet.

  6. You’ll need to run the above script on every startup. To automate this save the following systemd service /etc/systemd/system/dom0-network-direct.service

    [Unit]
    Description=Connect network to dom0
    
    [Service]
    Type=oneshot
    ExecStart=/home/user/bin/dom0_network.sh
    
    [Install]
    WantedBy=multi-user.target
    
  7. Then, enable and start the SSH Server and the script on boot:

    sudo systemctl enable sshd
    sudo systemctl start sshd
       
    sudo systemctl enable dom0-network-direct
    sudo systemctl start dom0-network-direct
    

Note: If you want to install additional software in dom0 and your only network card was assigned to dom0, then instead of the usual sudo qubes-dom0-update <PACKAGE> now you run sudo dnf --setopt=reposdir=/etc/yum.repos.d install <PACKAGE>.

Development VM

SSH

Arrange firewall so you can reach the testbench from your qubes-dev VM. Generate SSH key in qubes-dev:

ssh-keygen -t ecdsa -b 521

Add the following section in .ssh/config in qubes-dev:

Host testbench
    # substitute username in testbench
    User user
    # substitute address of your testbench
    HostName 192.168.123.45

Passwordless SSH Login

To log to your testbench without entering password every time, copy your newly generated public key (id_ecdsa.pub) to ~/.ssh/authorized_keys on your testbench. You can do this easily by running this command on qubes-dev: ssh-copy-id -i ~/.ssh/id_ecdsa.pub user@192.168.123.45 (substituting with the actual username address of your testbench).

Scripting

This step is optional, but very helpful. Put these scripts somewhere in your ${PATH}, like /usr/local/bin.

qtb-runtests:

#!/bin/sh

ssh testbench python -m qubes.tests.run

qtb-install:

#!/bin/sh

TMPDIR=/tmp/qtb-rpms

if [ $# -eq 0 ]; then
        echo "usage: $(basename $0) <rpmfile> ..."
        exit 2
fi

set -e

ssh testbench mkdir -p "${TMPDIR}"
scp "${@}" testbench:"${TMPDIR}" || echo "check if you have 'scp' installed on your testbench"

while [ $# -gt 0 ]; do
        ssh testbench sudo rpm -i --replacepkgs --replacefiles "${TMPDIR}/$(basename ${1})"
        shift
done

qtb-iterate:

#!/bin/sh

set -e

# substitute path to your builder installation
pushd ${HOME}/builder >/dev/null

# the following are needed only if you have sources outside builder
#rm -rf qubes-src/core-admin
#make COMPONENTS=core-admin get-sources

make core-admin
qtb-install qubes-src/core-admin/rpm/x86_64/qubes-core-dom0-*.rpm
qtb-runtests

Hooking git

I (woju) have those two git hooks. They ensure tests are passing (or are marked as expected failure) when committing and pushing. For committing it is only possible to run tests that may be executed from git repo (even if the rest were available, I probably wouldn’t want to do that). For pushing, I also install RPM and run tests on testbench.

core-admin/.git/hooks/pre-commit: (you may retain also the default hook, here omitted for readability)

#!/bin/sh

set -e

python -c "import sys, qubes.tests.run; sys.exit(not qubes.tests.run.main())"

core-admin/.git/hooks/pre-push:

#!/bin/sh

exec qtb-iterate