feat: adds rust example (#2)

.gitignore

@@ -0,0 +1,2 @@
+# Rust
+target/

examples/rust/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "hello"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+clap = "4.5.17"

examples/rust/Earthfile

@@ -0,0 +1,68 @@
+VERSION 0.8
+
+IMPORT github.com/earthly/lib/rust:3.0.3 AS rust
+
+deps:
+  FROM rust:1.81
+
+  WORKDIR /work
+
+  COPY Cargo.lock Cargo.toml .
+  COPY cross.sh .
+
+  DO rust+INIT
+
+src:
+  FROM +deps
+
+  COPY --keep-ts --dir src .
+
+build:
+  FROM +src
+
+  ARG USEROS
+  ARG USERARCH
+
+  ARG OS=$USEROS
+  ARG ARCH=$USERARCH
+  ARG TARGET=$(./cross.sh ${OS}/${ARCH})
+
+  DO rust+CROSS --target ${TARGET}
+  DO rust+COPY_OUTPUT --output=".*?/release/[^\./]+"
+
+  SAVE ARTIFACT ./target/${TARGET}/release/hello hello
+
+release:
+  FROM scratch
+
+  ARG TARGETOS
+  ARG TARGETARCH
+  ARG USERPLATFORM
+
+  COPY \
+      --platform=$USERPLATFORM \
+      (+build/hello \
+      --OS=$TARGETOS \
+      --ARCH=$TARGETARCH) bin/hello
+
+  SAVE ARTIFACT bin/hello hello
+
+publish:
+  FROM debian:bookworm-slim
+  WORKDIR /workspace
+
+  ARG container="rust"
+  ARG tag="latest"
+
+  ARG TARGETOS
+  ARG TARGETARCH
+  ARG USERPLATFORM
+
+  COPY \
+      --platform=$USERPLATFORM \
+      (+build/hello \
+      --OS=$TARGETOS \
+      --ARCH=$TARGETARCH) /usr/local/bin/hello
+
+  ENTRYPOINT ["/usr/local/bin/hello"]
+  SAVE IMAGE ${container}:${tag}

examples/rust/blueprint.cue

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+version: "1.0.0"
+project: {
+	name: "rust"
+	ci: targets: {
+		build: {
+			privileged: true
+		}
+		release: {
+			platforms: [
+				"linux/amd64",
+				"linux/arm64",
+			]
+			privileged: true
+		}
+		publish: {
+			platforms: [
+				"linux/amd64",
+				"linux/arm64",
+			]
+			privileged: true
+		}
+	}
+}

examples/rust/cross.sh

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+#!/usr/bin/env bash
+
+# Function to map Go-style platform to Rust target triple
+map_go_to_rust() {
+    local go_os=$1
+    local go_arch=$2
+
+    case "$go_os/$go_arch" in
+    linux/amd64)
+        echo "x86_64-unknown-linux-gnu"
+        ;;
+    linux/386)
+        echo "i686-unknown-linux-gnu"
+        ;;
+    linux/arm64)
+        echo "aarch64-unknown-linux-gnu"
+        ;;
+    linux/arm)
+        echo "armv7-unknown-linux-gnueabihf"
+        ;;
+    darwin/amd64)
+        echo "x86_64-apple-darwin"
+        ;;
+    darwin/arm64)
+        echo "aarch64-apple-darwin"
+        ;;
+    windows/amd64)
+        echo "x86_64-pc-windows-msvc"
+        ;;
+    windows/386)
+        echo "i686-pc-windows-msvc"
+        ;;
+    windows/arm64)
+        echo "aarch64-pc-windows-msvc"
+        ;;
+    *)
+        echo "Unsupported GOOS/GOARCH combination: $go_os/$go_arch"
+        exit 1
+        ;;
+    esac
+}
+
+# Check for correct number of arguments
+if [ "$#" -ne 1 ]; then
+    echo "Usage: $0 <GOOS/GOARCH>"
+    echo "Example: $0 linux/amd64"
+    exit 1
+fi
+
+# Split the input argument into GOOS and GOARCH
+input="$1"
+IFS='/' read -r go_os go_arch <<<"$input"
+
+# Call the function to get the Rust target triple
+map_go_to_rust "$go_os" "$go_arch"

examples/rust/src/main.rs

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+use clap::{Arg, Command};
+
+fn hello(name: &str) -> String {
+    format!("Hello, {}!", name)
+}
+
+fn main() {
+    // Define the version dynamically using an environment variable set at compile time
+    let version = env!("CARGO_PKG_VERSION");
+
+    // Initialize Clap Command
+    let matches = Command::new("Hello CLI")
+        .version(version)
+        .about("A simple CLI to greet users")
+        .arg(
+            Arg::new("input")
+                .help("The name to greet")
+                .index(1)
+                .required(false),
+        )
+        .get_matches();
+
+    // Get the input or default to "World"
+    let input = matches.get_one::<String>("input").map(|s| s.as_str()).unwrap_or("World");
+
+    // Output the greeting
+    println!("{}", hello(input));
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    // Test for the hello function
+    #[test]
+    fn test_hello() {
+        assert_eq!(hello("Alice"), "Hello, Alice!");
+        assert_eq!(hello("World"), "Hello, World!");
+        assert_eq!(hello(""), "Hello, !");
+    }
+}