Parsing the command line.

Author: dkorolev

.github/workflows/run.yml

@@ -10,5 +10,7 @@ jobs:
     steps:
       - name: clone
         uses: actions/checkout@v3
-      - name: run
+      - name: step00
         run: (cd step00_hw; ./run.sh)
+      - name: step01
+        run: (cd step01_cmdline; ./run.sh)

step00_hw/run.sh

@@ -3,4 +3,4 @@
 set -e
 
 docker build . -t demo
-docker run -t demo
+docker run --rm -t demo

step01_cmdline/Dockerfile

@@ -0,0 +1,22 @@
+# Build the binaries statically, and then run them from a separate container.
+FROM alpine AS build
+
+# Intentionally not installing `cargo`, etc. But it does need `clang`.
+RUN apk add rustup clang musl
+
+# Init local rust via `rustup`, including static targets builder.
+RUN rustup-init -y -t x86_64-unknown-linux-musl --no-modify-path
+RUN mv /root/.cargo/bin/* /usr/local/bin/
+
+# Build the project.
+COPY ./code /code
+WORKDIR /code
+RUN cargo build --release --target x86_64-unknown-linux-musl
+
+# Prepare the static binary.
+RUN cp ./target/x86_64-unknown-linux-musl/release/add /
+
+# The resulting container with the static binary only.
+FROM scratch
+COPY --from=build /add /add
+ENTRYPOINT ["/add"]

step01_cmdline/code/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "add"
+edition = "2021"
+
+[dependencies]
+clap = { version = "4.0", features = ["derive"] }

step01_cmdline/code/src/main.rs

@@ -0,0 +1,14 @@
+use clap::Parser;
+
+#[derive(Parser)]
+struct Args {
+  #[arg(long)]
+  a: u32,
+  #[arg(long)]
+  b: u32,
+}
+
+fn main() {
+  let args = Args::parse();
+  println!("{} + {} = {}", args.a, args.b, args.a + args.b);
+}

step01_cmdline/run.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+set -e
+
+docker build . -t demo
+docker run --rm -t demo --a 1 --b 2
+docker run --rm -t demo --a 3 --b 4