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Ryll Documentation

What is Ryll?

Ryll is a multi-modal SPICE VDI client, written in Rust. It began life as a purpose-built test client for performance testing of the Kerbside SPICE proxy, and has since grown into a client suitable for day-to-day interactive use — while keeping the instrumentation that made it useful for testing.

Background

Kerbside is a SPICE protocol native proxy that sits between SPICE clients and servers. Unlike layer 4 proxies that simply pass through unparsed traffic, Kerbside understands the SPICE protocol itself, allowing it to make intelligent routing and optimization decisions.

Getting Kerbside integrated into OpenStack has been a long process (see kerbside-patches), and now the focus has started to shift to performance validation.

What's With The Name?

Honestly, I am not super into Star Wars or anything, but "ryll" was the first good spice pun I came across. To quote the excellently named Wookieepedia:

Ryll was a precious ore harvested from the mines of Ryloth, and could also be found in the Krost Mountains on Aaloth. It had military and scientific applications, but could also be used as a drug in the form of refined spice, which was less effective than glitterstim.

https://starwars.fandom.com/wiki/Ryll

I guess I should think of a project to name "glitterstim" now too.

Why Build a Custom Client?

Existing SPICE clients like remote-viewer (spice-gtk) are designed for end-user use. They work well for connecting to VMs, but they're not designed to be instrumented for performance testing.

Ryll was originally built to:

  1. Generate controlled traffic - Predictable workloads for benchmarking
  2. Measure latency precisely - Track time from keystroke to display update
  3. Run headless - Automated testing without GUI overhead
  4. Be fully instrumented - Every metric needed for proxy performance analysis

Those goals still stand, but along the way ryll grew broad enough protocol coverage (display, cursor, inputs, audio, USB redirection, WebDAV folder sharing) and enough delivery modes (desktop GUI, headless, web browser) that it is now a practical client for real workloads, not just test ones.

The Testing Setup

┌─────────┐         ┌───────────┐         ┌─────────────┐
│  ryll   │────────▶│ kerbside  │────────▶│ SPICE server│
│ (client)│         │  (proxy)  │         │   (QEMU)    │
└─────────┘         └───────────┘         └─────────────┘
     │                    │                      │
     │                    │                      │
     ▼                    ▼                      ▼
  Metrics:            Metrics:              Metrics:
  - Latency           - Throughput          - Server-side
  - Frame rate        - Connection time       processing
  - Bytes in/out      - Protocol overhead

With ryll, we can:

  • Measure end-to-end latency through the proxy
  • Compare performance with and without the proxy
  • Identify bottlenecks in the proxy implementation
  • Validate that the proxy doesn't degrade user experience

Future Direction

It's likely that a custom SPICE server will also be needed, to control both ends of the traffic through the proxy. This would allow:

  • Generating specific display patterns (gradients, text, video-like content)
  • Precise timing of server-side events
  • Controlled latency injection for testing
  • Complete instrumentation of the entire path

Documentation Index

Project Files

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