feat(users/flokli): add NixCon 2023 presentation r/6829

This adds the materials for the talk held at NixCon 2023, Darmstadt.

It seems it's not really possible to export a PDF out of this,
at least I couldn't get reveal-md to do it properly.

The video recordings live on
https://media.ccc.de/v/nixcon-2023-35254-tvix and
https://www.youtube.com/watch?v=j67prAPYScY .

Change-Id: Id27dc8c8637ffd455981141383c54d8d1484679e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9750
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

1 files changed, 294 insertions, 0 deletions

diff --git a/users/flokli/presentations/2023-09-09-nixcon-tvix/presentation.md b/users/flokli/presentations/2023-09-09-nixcon-tvix/presentation.md
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+---
+author:
+- Florian Klink
+date: 2023-09-09
+title: "Tvix: Status update"
+theme: moon
+revealOptions:
+  transition: 'fade'
+---
+
+# Tvix: Status update
+
+![Tvix Logo](tvix-logo.png)
+
+2023-09-09
+
+Florian Klink
+
+---
+
+## Whoami
+
+- flokli
+- nixpkgs contributor since 2018, maintaining systemd, nsncd and some
+  more stuff
+- Freelance Nix/DevOps consultant
+- I spend too much time on computers :-)
+
+---
+
+## What is Tvix?
+
+- A new implementation of Nix
+- modular
+- written in Rust
+- developed in the [TVL](https://tvl.fyi) monorepo
+- subtree exported to [github:tvlfyi/tvix](https://github.com/tvlfyi/tvix)
+
+---
+
+## Structure
+
+- strong separation between **Evaluator**, **Store** and **Builder**
+- Defined interfaces between different components (Protobuf/gRPC) <!-- .element: class="fragment" -->
+  - Allows adding to/combining with your own components <!-- .element: class="fragment" -->
+- <!-- .element: class="fragment" --> A lot of helper code for some of the Nix internals in the `nix-compat` crate
+
+Note: Derivation types, serializers. NAR writers, nixbase32 enc/dec, Nix Hash function, stringparsing etc.
+
+----
+
+![crate-deps.svg](crate-deps.svg)
+
+---
+
+## Evaluator: Design
+
+- <!-- .element: class="fragment" --> 
+  Nix code is parsed via [rnix](https://github.com/nix-community/rnix-parser)
+- <!-- .element: class="fragment" -->
+  AST traversal, generate bytecode (with some transformations)
+- <!-- .element: class="fragment" -->
+  Bytecode is executed by an abstract machine with a Nix-specific instruction set
+
+----
+
+## Evaluator: Design
+
+- <!-- .element: class="fragment" -->
+  Builtins are separate from the "evaluator core"
+  - <!-- .element: class="fragment" -->
+    inject your own builtins
+  - <!-- .element: class="fragment" -->
+    this includes `builtins.derivation`!
+- <!-- .element: class="fragment" -->
+  IO is nicely abstracted away
+  - <!-- .element: class="fragment" -->
+    We can run a Nixlang subset without IO in wasm (see [tvixbolt](https://tvixbolt.tvl.su/)),
+    or parse Nix into a config struct with `tvix-serde`
+
+----
+
+<!-- <video class="r-stretch" src="./tvixbolt.webm"></video> -->
+<a href="./tvixbolt.webm">Tvixbolt Demo</a>
+
+----
+
+### Evaluator: Current Work
+
+- <!-- .element: class="fragment" -->
+  Current goal: **evaluate nixpkgs the same way as Nix does**
+- <!-- .element: class="fragment" -->
+  Checked by comparing the calculated output paths, which checks correctness of all \"parent\" output paths too.
+- <!-- .element: class="fragment" -->
+  Required implementing a lot of Nix internals in `nix-compat`, and `tvix-store` (A-Term, hash modulo, NAR writer/hasher)
+
+Note: Getting output hashing correct, and exposing this in a re-usable fashion took quite some iterations to get right.
+
+----
+
+### Evaluator: Current Work (cont.)
+- <!-- .element: class="fragment" -->
+  🎉 Already correct for (and continously checked by CI on every commit):
+  - <!-- .element: class="fragment" -->
+  `stdenv`, `hello`
+  - <!-- .element: class="fragment" -->
+  `pkgsCross.aarch64-multiplatform.stdenv`, `pkgsCross.aarch64-multiplatform.hello`
+- <!-- .element: class="fragment" -->
+  Some work left for more complicated expressions
+  - <!-- .element: class="fragment" -->
+    infinite recursion [when inheriting from a `builtins.tryEval` multiple times](https://b.tvl.fyi/281)
+  - <!-- .element: class="fragment" -->
+    small details around file imports
+- <!-- .element: class="fragment" -->
+  Not too much performance finetuning until we're correct first.
+
+----
+
+### Evaluator: Demo
+
+[![asciicast](https://asciinema.org/a/MH4tuVPLsKewJSGJUYEyIKUpj.svg)](https://asciinema.org/a/MH4tuVPLsKewJSGJUYEyIKUpj)
+
+---
+
+## Store: Design
+
+- <!-- .element: class="fragment" -->
+  Uses a very different underlying data model:
+  - <!-- .element: class="fragment" -->
+    Nix stores on a per- `StorePath` granularity
+  - <!-- .element: class="fragment" -->
+    tvix-store uses a Merkle DAG of directories, similar to git trees, but with [BLAKE3](https://github.com/BLAKE3-team/BLAKE3) digests as pointers.
+  - <!-- .element: class="fragment" -->
+    Compat layer in front to still render/calculate NAR on demand where needed
+  - <!-- .element: class="fragment" -->
+    Substitution, caching, ... possible to describe via composition/layering
+
+----
+
+![tvix-store graph](tvix-store-graph.svg)
+
+----
+
+### Store: Advantages
+
+- <!-- .element: class="fragment" -->
+  Less downloading of data that didn't change
+- <!-- .element: class="fragment" -->
+  Less duplicate data on disk/storage
+- <!-- .element: class="fragment" -->
+  Inherently content-addressed, so P2P substitution possible
+- <!-- .element: class="fragment" -->
+  Allows doing verified blob streaming ([BAO](https://github.com/oconnor663/bao), [bao-tree](https://github.com/n0-computer/bao-tree))
+- <!-- .element: class="fragment" -->
+  Protocol has some \"smarter\" methods to avoid roundtrips, but could all be statically pre-rendered
+- <!-- .element: class="fragment" -->
+  Very little data that needs to be fetched from a trusted party (or be signed)
+
+Note: Our way of addressing blobs by their raw blake3 digest is natively compatible with iroh, the IPFS Re-implementation in Rust
+
+----
+
+### Store: Status
+
+- <!-- .element: class="fragment" -->
+  Whole Merkle-based store implementation (and Nix NAR compat layer) is there
+  - <!-- .element: class="fragment" -->
+    exercised by the output path CI tests, and a test suite.
+  - <!-- .element: class="fragment" -->
+    three backends (Sled, in-memory, gRPC client)
+  - <!-- .element: class="fragment" -->
+    more backends and more test suites planned.
+- <!-- .element: class="fragment" -->
+  FUSE filesystem to expose the store (to Tvix Builders, \"appliances\") <!-- .element: class="fragment" -->
+
+Note: backends: RocksDB, sqlite, s3. fuse: lazy fetching of build input files | think about a minimal initrd to bring up network and mount the store, then run any closure.
+
+----
+
+### Store: Demo
+
+[![asciicast](https://asciinema.org/a/YFB9yycHdx0OUH9N0WdAkIYua.svg)](https://asciinema.org/a/YFB9yycHdx0OUH9N0WdAkIYua)
+
+----
+
+### Store: Status (cont.)
+- <!-- .element: class="fragment" -->
+  More work on store composition needed (necessary for substition and caching)
+- <!-- .element: class="fragment" -->
+  More work on more granular blob substititon needed.
+- <!-- .element: class="fragment" -->
+  More work on bridges with Nix needed
+  - <!-- .element: class="fragment" -->
+    Get Nix to talk to a tvix-store
+  - <!-- .element: class="fragment" -->
+    Expose existing binary caches to tvix-store
+
+---
+
+### Builder: Design
+
+- <!-- .element: class="fragment" -->
+  Build requests/Build protocol is less Nix-specific
+  - <!-- .element: class="fragment" -->
+    allows reusing builders for other usages (non-sandboxed builds, other build systems, playing with other addressing mechanisms)
+- <!-- .element: class="fragment" -->
+  Distinction between a **specific build attempt** and the **general build recipe**
+  - <!-- .element: class="fragment" -->
+    allows keeping metadata about failed builds
+  - <!-- .element: class="fragment" -->
+    stats (memory/cpu consumption)
+  - <!-- .element: class="fragment" -->
+    comparing different produced binary outputs (r11y)
+
+----
+
+### Builder: Design
+
+- <!-- .element: class="fragment" -->
+  Invididual builds can be run in your desired container/virt engine/scheduler, as long as it speaks the same Build API
+- <!-- .element: class="fragment" -->
+  Build API composition/proxying, similar to Store composition
+- <!-- .element: class="fragment" -->
+  allows "unattended building" (evaluate nixpkgs locally and send all build requests to a remote builder)
+- <!-- .element: class="fragment" -->
+  allows tailing logs from currently/already running builds
+
+----
+
+### Builder: Status
+
+- <!-- .element: class="fragment" -->
+  Dummy Builder implementation in `go-nix` (using OCI)
+- <!-- .element: class="fragment" -->
+  Some scribble notes on the Build Protocol
+- <!-- .element: class="fragment" -->
+  Glue code to trigger builds from inside `builtins.derivation` needs to be written
+- <!-- .element: class="fragment" -->
+  Builder implementation (using `systemd-nspwan` or some container engine needs to be written.
+- <!-- .element: class="fragment" -->
+  Web interface to visualize store contents and build graphs/builds/logs
+
+---
+
+## Contributing
+
+- <!-- .element: class="fragment" -->
+  Join the IRC channel (`#tvl` on `hackint`), bridged to Matrix and XMPP
+- <!-- .element: class="fragment" -->
+  Check our issue tracker
+- <!-- .element: class="fragment" -->
+  Try to use it and tell us how you broke it!
+- <!-- .element: class="fragment" -->
+  Add various Nix bits to `nix-compat`
+
+Note: or if you like what you seeing and want to sponsor parts, that's also cool :-)
+
+---
+
+# Thanks to...
+
+- <!-- .element: class="fragment" -->
+  all TVL contributors (some drive-by, some long-term contributors)
+- <!-- .element: class="fragment" -->
+  countless Nix community members for their input on the architecture and rubberducking
+- <!-- .element: class="fragment" -->
+  NLNET and others to sponsor parts of this
+
+----
+
+# Questions?
+
+<style>
+.container{
+    display: flex;
+}
+.col{
+    flex: 1;
+}
+</style>
+
+<div class="container">
+
+<div class="col">
+Florian Klink / <a href="https://flokli.de">flokli.de</a><br />
+<img src="qrcode-flokli.svg" />
+</div>
+
+<div class="col">
+Tvix / <a href="https://tvix.dev">tvix.dev</a><br />
+<img src="qrcode-tvix.svg" />
+</div>
+
+</div>