203 lines
8.5 KiB
Markdown
203 lines
8.5 KiB
Markdown
---
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title: "Wasmcloud Progress: Rewritten in Rust"
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date: 2020-10-31
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series: olin
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tags:
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- wasm
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- wasmcloud
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- wasmer
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---
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# Wasmcloud Progress: Rewritten in Rust
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It's been a while since I had the [last update for
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Wasmcloud](/blog/wasmcloud-progress-2019-12-08). In that time I have gotten a
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lot done. As the title mentions I have completely rewritten Wasmcloud's entire
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stack in Rust. Part of the reason was for [increased
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speed](/blog/pahi-benchmarks-2020-03-26) and the other part was to get better at
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Rust. I also wanted to experiment with running Rust in production and this has
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been an excellent way to do that.
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Wasmcloud is going to have a few major parts:
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- The API (likely to be hosted at `api.wasmcloud.app`)
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- The Executor (likely to be hosted at `run.wasmcloud.lgbt`)
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- The Panel (likely to be hosted at `panel.wasmcloud.app`)
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- The command line tool `wasmcloud`
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- The Documentation site (likely to be hosted at `docs.wasmcloud.app`)
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These parts will work together to implement a functions as a service platform.
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[The executor is on its own domain to prevent problems like <a
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href="https://github.blog/2013-04-05-new-github-pages-domain-github-io/">this
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GitHub Pages vulnerability</a> from 2013. It is on a `.lgbt` domain because LGBT
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rights are human rights.](conversation://Mara/hacker)
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I have also set up a (slightly sarcastic) landing page at
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[wasmcloud.app](https://wasmcloud.app) and a twitter account at
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[@usewasmcloud](https://twitter.com/usewasmcloud). Right now these are
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placeholders. I wanted to register the domains before they were taken by anyone
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else.
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## Architecture
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My previous attempt at Wasmcloud had more of a four tier webapp setup. The
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overall stack looked something like this:
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- Nginx in front of everything
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- The api server that did about everything
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- The executors that waited on message queues to run code and push results to
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the requester
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- Postgres
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- A message queue to communicate with the executors
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- IPFS to store WebAssembly modules
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In simple testing, this works amazingly. The API server will send execution
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requests to the executors and everything will usually work out. However, the
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message queue I used was very "fire and forget" and had difficulties with
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multiple executors set up to listen on the queue. Additionally, the added
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indirection of needing to send the data around twice means that it would have
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difficulties scaling globally due to ingress and egress data costs. This model
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is solid and _probably would have worked_ with some compression or other
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improvements like that, but overall I was not happy with it and decided to scrap
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it while I was porting the executor component to Rust. If you want to read the
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source code of this iteration of Wasmcloud, take a look
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[here](https://tulpa.dev/within/wasmcloud).
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The new architecture of Wasmcloud looks something like this:
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- Nginx in front of everything
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- An API server that handles login with my gitea instance
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- The executor server that listens over https
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- Postgres
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- Backblaze B2 to store WebAssembly modules
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The main change here is the fact that the executor listens over HTTPS, avoiding
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_a lot_ of the overhead involved in running this on a message queue. It's also
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much simpler to implement and allows me to reuse a vast majority of the
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boilerplate that I developed for the Wasmcloud API server.
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This new version of Wasmcloud is also built on top of
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[Wasmer](https://wasmer.io/). Wasmer is a seriously fantastic library for this
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and getting up and running was absolutely trivial, even though I knew very
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little Rust when I was writing [pa'i](/blog/pahi-hello-world-2020-02-22). I
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cannot recommend it enough if you ever want to execute WebAssembly on a server.
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## Roadmap
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At this point, I can create new functions, upload them to the API server and
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then trigger them to be executed. The output of those functions is not returned
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to the user at this point. I am working on ways to implement that. There is also
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very little accounting for what resources and system calls are used, however it
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does keep track of execution time. The executor also needs to have the request
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body of the client be wired to the standard in of the underlying module, which
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will enable me to parse CGI replies from WebAssembly functions. This will allow
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you to host HTTP endpoints on Wasmcloud using the same code that powers
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[this](https://olin.within.website) and
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[this](http://cetacean.club/cgi-bin/olinfetch.wasm).
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I also need to go in and completely refactor the
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[olin](https://github.com/Xe/pahi/tree/main/wasm/olin/src) crate and make the
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APIs much more ergonomic, not to mention make the HTTP client actually work
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again.
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Then comes the documentation. Oh god there will be so much documentation. I will
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be _drowning_ in documentation by the end of this.
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I need to write the panel and command line tool for Wasmcloud. I want to write
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the panel in [Elm](https://elm-lang.org/) and the command line tool in Rust.
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There is basically zero validation for anything submitted to the Wasmcloud API.
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I will need to write validation in order to make it safer.
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I may also explore enabling support for [WASI](https://wasi.dev/) in the future,
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but as I have stated before I do not believe that WASI works very well for the
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futuristic plan-9 inspired model I want to use on Wasmcloud.
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Right now the executor shells out to pa'i, but I want to embed pa'i into the
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executor binary so there are fewer moving parts involved.
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I also need to figure out what I should do with this project in general. It
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feels like it is close to being productizable, but I am in a very bad stage of
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my life to be able to jump in headfirst and build a company around this. Visa
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limitations also don't help here.
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## Things I Learned
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[Rocket](https://rocket.rs) is an absolutely fantastic web framework and I
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cannot recommend it enough. I am able to save _so much time_ with Rocket and its
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slightly magic use of proc-macros. For an example, here is the entire source
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code of the `/whoami` route in the Wasmcloud API:
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```rust
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#[get("/whoami")]
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#[instrument]
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pub fn whoami(user: models::User) -> Json<models::User> {
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Json(user)
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}
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```
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The `FromRequest` instance I have on my database user model allows me to inject
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the user associated with an API token purely based on the (validated against the
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database) claims associated with the JSON Web Token that the user uses for
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authentication. This then allows me to make API routes protected by simply
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putting the user model as an input to the handler function. It's magic and I
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love it.
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Postgres lets you use triggers to automatically update `updated_at` fields for
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free. You just need a function that looks like this:
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```sql
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CREATE OR REPLACE FUNCTION trigger_set_timestamp()
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RETURNS TRIGGER AS $$
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BEGIN
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NEW.updated_at = NOW();
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RETURN NEW;
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END;
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$$ LANGUAGE plpgsql;
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```
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And then you can make triggers for your tables like this:
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```sql
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CREATE TRIGGER set_timestamp_users
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BEFORE UPDATE ON users
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FOR EACH ROW
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EXECUTE PROCEDURE trigger_set_timestamp();
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```
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Every table in Wasmcloud uses this in order to make programming against the
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database easier.
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The symbol/number layer on my Moonlander has been _so good_. It looks something
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like this:
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And it makes using programming sigils _so much easier_. I don't have to stray
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far from the homerow to hit the most common ones. The only one that I still have
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to reach for is `_`, but I think I will bind that to the blank key under the `]`
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key.
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The best programming music is [lofi hip hop radio - beats to study/relax
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to](https://www.youtube.com/watch?v=5qap5aO4i9A). Second best is [Animal
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Crossing music](https://www.youtube.com/watch?v=2nYNJLfktds). They both have
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this upbeat quality that makes the ideas melt into code and flow out of your
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hands.
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---
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Overall I'd say this is pretty good for a week of hacking while learning a new
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keyboard layout. I will do more in the future. I have plans. To read through the
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(admittedly kinda hacky/awful) code I've written this week, check out [this git
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repo](https://tulpa.dev/wasmcloud/wasmcloud). If you have any feedback, please
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[contact me](/contact). I will be happy to answer any questions.
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As far as signups go, I am not accepting any signups at the moment. This is
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pre-alpha software. The abuse story will need to be figured out, but I am fairly
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sure it will end up being some kind of "pay or you can only run the precompiled
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example code in the documentation" with some kind of application process for the
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"free tier" of Wasmcloud. Of course, this is all theoretical and hinges on
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Wasmcloud actually being productizable; so who knows?
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Be well.
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