chore: Use cargo chef to speed up docker build [load test: warn] (#561)

Dockerfile

@@ -1,51 +1,41 @@
-# Docker 17.05 or higher required for multi-stage builds
+# !!!NOTE!!!: Ensure Rust version matches CI's in .circleci/config.yml
+FROM lukemathwalker/cargo-chef:latest-rust-1.68-bullseye AS chef
+WORKDIR /app
+
+FROM chef AS planner
+COPY . .
+RUN cargo chef prepare --recipe-path recipe.json
+
+FROM chef AS builder
+COPY --from=planner /app/recipe.json recipe.json
+# Build dependencies - this is the caching Docker layer!
+RUN cargo chef cook --release --recipe-path recipe.json
 
-# Change this to be your application's name
-ARG APPNAME=contile
+# Build application
+COPY . .
 # This build arg is used to pass the version (e.g. the commit SHA1 hash) from CI
-# when building the application.
+# when building the application. Bring it into scope here for better caching for
+# Cargo Chef.
 ARG VERSION=unset
+RUN CONTILE_VERSION=${VERSION} cargo build --release
 
-# NOTE: Ensure builder's Rust version matches CI's in .circleci/config.yml
-FROM rust:1.68-slim-bullseye as builder
-ARG APPNAME
-ARG VERSION
-ADD . /app
+FROM debian:bullseye-slim AS runtime
 WORKDIR /app
 
-# Make sure that this matches in .travis.yml
-# ARG RUST_TOOLCHAIN=nightly
-RUN \
-    apt-get -qq update && \
-    apt-get install libssl-dev pkg-config -y && \
-    \
-    rustup default ${RUST_TOOLCHAIN} && \
-    cargo --version && \
-    rustc --version && \
-    mkdir -m 755 bin && \
-    CONTILE_VERSION=${VERSION} cargo build --release && \
-    cp /app/target/release/${APPNAME} /app/bin
-
-
-FROM debian:bullseye-slim
-ARG APPNAME
-
-# FROM debian:buster  # for debugging docker build
 RUN \
     groupadd --gid 10001 app && \
     useradd --uid 10001 --gid 10001 --home /app --create-home app && \
     \
     apt-get -qq update && \
     apt-get -qq install -y libssl-dev pkg-config ca-certificates && \
-    rm -rf /var/lib/apt/lists
+    rm -rf /var/lib/apt/lists && \
+    mkdir -m 755 bin
 
-COPY --from=builder /app/bin /app/bin
+COPY --from=builder /app/target/release/contile /app/bin
 COPY --from=builder /app/version.json /app
 COPY --from=builder /app/entrypoint.sh /app
 
-WORKDIR /app
 USER app
 
-# ARG variables aren't available at runtime
-ENV BINARY=/app/bin/${APPNAME}
+ENV BINARY=/app/bin/contile
 ENTRYPOINT ["/app/entrypoint.sh"]