Implement docker build

Dockerfile

@@ -0,0 +1,27 @@
+FROM ekidd/rust-musl-builder:stable as builder
+
+# RUN adduser -D hoc
+RUN useradd -U 10001 dummy
+
+# create new cargo project
+RUN USER=rust cargo init --bin
+# copy build config
+COPY --chown=rust ./Cargo.lock ./Cargo.lock
+COPY --chown=rust ./Cargo.toml ./Cargo.toml
+# build to cache dependencies
+RUN cargo build --release
+# delete build cache to prevent caching issues later on
+RUN rm -r ./target/x86_64-unknown-linux-musl/release/.fingerprint/gitache-*
+
+COPY ./src ./src
+# build source code
+RUN cargo build --release
+
+FROM scratch
+
+COPY --from=builder /etc/passwd /etc/passwd
+USER dummy
+
+COPY --from=builder /home/rust/src/target/x86_64-unknown-linux-musl/release/gitache /
+
+ENTRYPOINT ["/gitache"]