krata/DEV.md

Development Guide

Structure

krata is composed of four major executables:

Executable	Runs On	User Interaction	Dev Runner	Code Path
kratad	host	backend daemon	./hack/debug/kratad.sh	crates/daemon
kratanet	host	backend daemon	./hack/debug/kratanet.sh	crates/network
kratactl	host	CLI tool	./hack/debug/kratactl.sh	crates/ctl
kratazone	zone	none, zone init	N/A	crates/zone

You will find the code to each executable available in the bin/ and src/ directories inside it's corresponding code path from the above table.

Environment

Component	Specification	Notes
Architecture	x86_64	aarch64 support is still in development
Memory	At least 6GB	dom0 will need to be configured with lower memory limit to give krata zones room
Xen	4.17+
Debian	stable / sid	Debian is recommended due to the ease of Xen setup
rustup	any	Install Rustup from https://rustup.rs

Setup Guide

1. Install the specified Debian version on a x86_64 host capable of KVM (NOTE: KVM is not used, Xen is a type-1 hypervisor).

2. Install required packages:

$ apt install git xen-system-amd64 build-essential musl-tools \
      protobuf-compiler libprotobuf-dev squashfs-tools erofs-utils

3. Install rustup for managing a Rust environment.

Make sure to install the targets that you need for krata:

$ rustup target add x86_64-unknown-linux-gnu
$ rustup target add x86_64-unknown-linux-musl

4. Configure /etc/default/grub.d/xen.cfg to give krata zones some room:

# Configure dom0_mem to be 4GB, but leave the rest of the RAM for krata zones.
GRUB_CMDLINE_XEN_DEFAULT="dom0_mem=4G,max:4G"

After changing the grub config, update grub: update-grub

Then reboot to boot the system as a Xen dom0.

You can validate that Xen is setup by running dmesg | grep "Hypervisor detected" and ensuring it returns a line like Hypervisor detected: Xen PV, if that is missing, the host is not running under Xen.

5. Clone the krata source code:

$ git clone https://github.com/edera-dev/krata.git krata
$ cd krata

6. Fetch the zone kernel image:

$ ./hack/kernel/fetch.sh -u

7. Copy the zone kernel artifacts to /var/lib/krata/zone/kernel so it is automatically detected by kratad:

$ mkdir -p /var/lib/krata/zone
$ cp target/kernel/kernel-x86_64 /var/lib/krata/zone/kernel
$ cp target/kernel/addons-x86_64.squashfs /var/lib/krata/zone/addons.squashfs

8. Launch ./hack/debug/kratad.sh and keep it running in the foreground.
9. Launch ./hack/debug/kratanet.sh and keep it running in the foreground.
10. Run kratactl to launch a zone:

$ ./hack/debug/kratactl.sh zone launch --attach alpine:latest

To detach from the zone console, use Ctrl + ] on your keyboard.

To list the running zones, run:

$ ./hack/debug/kratactl.sh zone list

To destroy a running zone, copy it's UUID from either the launch command or the zone list and run:

$ ./hack/debug/kratactl.sh zone destroy ZONE_UUID