Cargo chef not effective with Dioxus

[timakro]

I copied the Dockerfile from the docs and it seems that cargo chef is not fully effective. If I don't touch my dependencies and only make a modification in my main.rs, the dx bundle command still seems to compile most (all?) dependencies.

[LilahTovMoon]

I've experienced the same issue. I'm no expert so someone on the core team might correct things I'm about to write.

It seems like cargo build -r will put things into ./target/release. When I run dx build --platform web -r, it puts things into ./target/web-release, ./target/server-release, and ./target/wasm32-unknown-unknown/web-release.

So, it seems like Dioxus is looking at different locations than where cargo (and presumably chef) are going to put things.

This is what I do instead:

First, I created a build.rs file which is just a dummy file used so we can build dependencies. Since it won't ever be changing, that layer will get cached:

// DO NOT EDIT THIS FILE. IT IS ONLY USED FOR BUILDING DEPENDENCIES IN DOCKER
use dioxus::prelude::*;

fn main() {
    dioxus::launch(App);
}

#[component]
fn App() -> Element {
    rsx! {
        h1 { "Build" }
    }
}

Then I have my Dockerfile:

FROM rust:1 AS builder
WORKDIR /app
ENV PATH="/.cargo/bin:$PATH"
RUN cargo install dioxus-cli --version 0.7.0-alpha.2 --root /.cargo
COPY ./src/build.rs ./src/main.rs
COPY ./Cargo.toml ./Cargo.lock ./
RUN dx build --platform web -r
COPY . .
RUN dx bundle --platform web -r

After installing the dioxus-cli, it copies the build.rs, Cargo.toml, and Cargo.lock over. It then builds the layer with all the dependencies.

Then it copies over everything (the whole app rather than just the dummy build.rs) and runs dx bundle to build the actual application and it seems to find the pre-built dependencies with the time going from around 100 seconds to about 20 seconds for that step (since it already has the dependencies built).

For chef to work (beyond using the same directories as dx), I think you might also need to add a --target wasm32-unknown-unknown --target x86_64-unknown-linux-gnu so that it'd build both targets. But given that dx doesn't seem to be using the target directories that cargo/chef are making, it doesn't really matter at this point.

This is basically adapted from: https://www.lpalmieri.com/posts/fast-rust-docker-builds/#caching-rust-builds (that's by cargo-chef's author). This uses a very basic Dioxus app (the build.rs file) instead of an empty main so that it won't fail on trying to deal with the wasm.

EDIT: I also did a cargo install instead of binstall so the first build will be slow (until that layer is cached), but if binstall is working fine for you, you can simply replace that part of my code.