Add Dockerfile

Dockerfile

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+################
+##### Builder
+FROM rust:1.82.0-slim AS builder
+
+WORKDIR /usr/src
+
+COPY . /usr/src
+
+## Install target platform (Cross-Compilation) --> Needed for Alpine
+RUN rustup target add x86_64-unknown-linux-musl
+
+# This is a dummy build to get the dependencies cached.
+RUN cargo build --target x86_64-unknown-linux-musl --release
+
+## Touch main.rs to prevent cached release build
+RUN touch /usr/src/server/src/main.rs
+
+# This is the actual application build.
+RUN cargo build --package server --target x86_64-unknown-linux-musl --release
+
+################
+##### Runtime
+FROM alpine:3.20.3 AS runtime
+
+# Copy application binary from builder image
+COPY --from=builder /usr/src/target/x86_64-unknown-linux-musl/release/saslauthd /usr/local/bin
+
+
+# Run the application
+CMD ["/usr/local/bin/saslauthd"]