Update Alpine to 3.21.3 (#51)

* Update Alpine to 3.21.3

* Address review comments (update README.md)

Author: reta

Dockerfile

@@ -9,7 +9,7 @@
 # When updating, update the README and the alpine_version ARG
 #  * Use current version from https://alpinelinux.org/downloads/
 #  * ARGs repeat because Dockerfile ARGs are layer specific but will reuse the value defined here.
-ARG alpine_version=3.21.2
+ARG alpine_version=3.21.3
 
 # We copy files from the context into a scratch container first to avoid a problem where docker and
 # docker-compose don't share layer hashes https://github.com/docker/compose/issues/883 normally.

README.md

@@ -20,15 +20,15 @@ docker run -ti --rm ghcr.io/openzipkin/alpine:3.21.2
 ## Release process
 Build the `Dockerfile` using the current version from https://alpinelinux.org/downloads/:
 ```bash
-# Note 3.21.2 not 3.21!
-./build-bin/build 3.21.2
+# Note 3.21.3 not 3.21!
+./build-bin/build 3.21.3
 ```
 
 Next, verify the built image matches that version:
 ```bash
 docker run --rm openzipkin/alpine:test -c 'cat /etc/alpine-release'
-3.21.2
+3.21.3
 ```
 
-To release the image, push a tag matching the arg to `build-bin/build` (ex `3.21.2`).
+To release the image, push a tag matching the arg to `build-bin/build` (ex `3.21.3`).
 This triggers a [GitHub Actions](https://github.com/openzipkin/docker-alpine/actions) job to push the image.