Create Dockerfile for tiny webserver image

This will build the WASM binary, generate the JS bindings, and then
copy them and the index.html into a BusyBox image for serving.

.dockerignore

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+.git/
+target/
+Dockerfile

Dockerfile

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+# This is a simple, stand-alone server image for hosting the WASM file.
+# It is not intended to integrate with other webpages, webservers, or sites
+# on an existing server. For that, you must patch the code yourself.
+FROM rust AS builder
+
+# Install build tools
+RUN rustup target add wasm32-unknown-unknown
+RUN cargo install --locked wasm-bindgen-cli
+
+# Build the program
+
+# Copy in only the Rust source so the builder doesn't discard any cached build
+# layers just because the README changed.
+COPY src/ src/
+COPY Cargo.toml Cargo.toml
+COPY Cargo.lock Cargo.lock
+COPY .cargo .cargo
+
+RUN cargo build --locked --target wasm32-unknown-unknown --release
+RUN wasm-bindgen \
+    --no-typescript \
+    --target web \
+    --out-dir out/ \
+    --out-name "chaos-game-rs" \
+    target/wasm32-unknown-unknown/release/chaos-game-rs.wasm
+
+
+# Copy WASM & JS to a new image for use
+FROM busybox:musl
+RUN mkdir -p /var/www
+COPY --from=builder out/ /var/www
+COPY index.html /var/www/index.html
+
+WORKDIR /var/www
+
+EXPOSE 8080/tcp
+
+CMD ["httpd", "-f"]