Modusfile

# This will act as our base image for building. It contains all the source files.
# It is defined for different rust channels, and will use rustup to switch to the
# correct channel.
build_env(rust_channel) :-
  from("rust:alpine")::set_workdir("/usr/src/app"),
  run("apk add --update --no-cache curl git musl-dev"),
  # install wasm-pack
  run("curl https://rustwasm.github.io/wasm-pack/installer/init.sh -sSf | sh"),
  rust_channel(rust_channel),
  copy(".", ".").

# This function selects the rust channel we want to use.
rust_channel(channel) :-
  # restrict the set of values for channel
  (channel = "stable"; channel = "nightly"; channel = "beta"),
  run(f"rustup default ${channel}").

# cargo_build(profile, out_dir).
# Think of the first argument as an input, and the second (out_dir) as an output.
cargo_build("dev", "target/debug") :- run("cargo build").
cargo_build("release", "target/release") :- run("cargo build --release").

wasm_build("dev") :- run("wasm-pack build --target web").
wasm_build("release") :- run("wasm-pack build --target web --release").

app(profile, channel) :-
  (
    from("alpine")::set_workdir("/usr/src/app"),
    (
      # This is a sub-image which builds the server binary
      build_env(channel)::set_workdir("server"),
      cargo_build(profile, out_dir)
    )::copy(f"${out_dir}/server", "."),
    (
      # Another sub-image which builds the client (frontend), resulting in all the necessary static assets.
      build_env(channel)::set_workdir("client"),
      wasm_build(profile),
      run("mkdir dist && mv index.html pkg dist/")
    )::copy("dist", "./dist")
  )::set_env("STATIC_DIR", "./dist")
   ::set_entrypoint("./server").