Adding Earthfile for CI

Earthfile

@@ -0,0 +1,27 @@
+VERSION 0.7
+FROM rust:alpine
+WORKDIR /rustbuild
+
+prepare-env:
+    RUN apk add --no-cache musl-dev libssl3 openssl-dev
+    RUN cargo search test # Super simple way to cache the cargo index
+
+docker-multi:
+    BUILD --platform linux/amd64 --platform linux/arm64 +docker
+
+build:
+    FROM +prepare-env
+    COPY . .
+    RUN cargo build --release
+    SAVE ARTIFACT target/release/rustocat rustocat
+
+docker:
+    FROM alpine
+    RUN apk add --no-cache libssl3
+    COPY +build/rustocat rustocat
+    ENTRYPOINT ["/bin/sh"]
+    CMD ["-c", "/rustbuild/rustocat"]
+    ARG EARTHLY_TARGET_TAG
+    ARG TAG=$EARTHLY_TARGET_TAG
+    SAVE IMAGE --push docker.hibas123.de/rustocat:latest
+    SAVE IMAGE --push docker.hibas123.de/rustocat:$TAG