Update to Alpine Linux 3.19 and improved README to show size differences for alpine versions.

Dockerfile

@@ -1,5 +1,5 @@
 # Start with a rust alpine image
-FROM rust:1-alpine3.16
+FROM rust:1-alpine3.19
 # This is important, see https://github.com/rust-lang/docker-rust/issues/85
 ENV RUSTFLAGS="-C target-feature=-crt-static"
 # if needed, add additional dependencies here
@@ -12,7 +12,7 @@ RUN cargo build --release
 RUN strip target/release/mini-docker-rust
 
 # use a plain alpine image, the alpine version needs to match the builder
-FROM alpine:3.16
+FROM alpine:3.19
 # if needed, install additional dependencies here
 RUN apk add --no-cache libgcc
 # copy the binary into the final image

README.md

@@ -2,7 +2,16 @@
 
 Very small rust docker image.
 
-This is an example project on how to build very small docker images for a rust project. The resulting image for a working hello world was about 6.01MB during my tests.
+This is an example project on how to build very small docker images for a rust project. The resulting image for a working `hello world` was 5.69MB in the case of Alpine 3.16. Alpine versions have changed in size with past releases (see below a table with historic sizes of the docker images). Using end-of-life Alpine/Rust releases is not advised (even if they might be slightly smaller). Checked sizes with `docker system df -v`
+
+| Alpine      | Size   |
+| ----------- | ------ |
+| alpine:3.19 | 8.22MB |
+| alpine:3.18 | 8.22MB | 
+| alpine:3.17 | 7.95MB | 
+| alpine:3.16 | 5.69MB | 
+| alpine:3.15 | 5.74MB |
+| alpine:3.14 | 5.73MB |
 
 This repo is trying to keep the docker overhead to a minimum without sacrificing performance or the usability implications of using `FROM scratch`. If you want to reduce the binary size further you might be interested in [johnthagen/min-sized-rust](https://github.com/johnthagen/min-sized-rust).