krata/DEV.md
2024-03-22 23:59:02 +00:00

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# 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/kratad |
| kratanet | host | backend daemon | ./hack/debug/kratanet.sh | crates/kratanet |
| kratactl | host | CLI tool | ./hack/debug/kratactl.sh | crates/kratactl |
| krataguest | guest | none, guest init | N/A | crates/krataguest |
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 will lower memory limit to give krata guests room |
| Xen | 4.17 | Temporary due to hardcoded interface version constants |
| 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 flex bison libelf-dev libssl-dev bc`
3. Install [rustup](https://rustup.rs) for managing a Rust environment.
4. Configure `/etc/default/grub.d/xen.cfg` to give krata guests some room:
```sh
# Configure dom0_mem to be 4GB, but leave the rest of the RAM for krata guests.
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 `xl info` and ensuring it returns useful information about the Xen hypervisor.
5. Clone the krata source code:
```sh
$ git clone https://github.com/edera-dev/krata.git krata
$ cd krata
```
6. Build a guest kernel image:
```sh
$ ./hack/kernel/build.sh
```
7. Copy the guest kernel image at `target/kernel/kernel-x86_64` to `/var/lib/krata/guest/kernel` to have it automatically detected by kratad.
8. Launch `./hack/debug/kratanet.sh` and keep it running in the foreground.
9. Launch `./hack/debug/kratad.sh` and keep it running in the foreground.
10. Run kratactl to launch a guest:
```sh
$ ./hack/debug/kratactl.sh launch --attach alpine:latest
```
To detach from the guest console, use `Ctrl + ]` on your keyboard.
To list the running guests, run:
```sh
$ ./hack/debug/kratactl.sh list
```
To destroy a running guest, copy it's UUID from either the launch command or the guest list and run:
```sh
$ ./hack/debug/kratactl.sh destroy GUEST_UUID
```