Add prom/busybox:alpine image

[maxhuebler]

@SuperQ @discordianfish

Fixes #50 #64 #65

Description

This PR introduces a new prom/busybox:alpine image variant based on Alpine Linux's static busybox binary.

Changes

• New Image Variant (alpine):

  • Added alpine/Dockerfile which performs a multi-stage build.
  • Uses alpine:latest as a builder to extract busybox-static, ca-certificates, and tzdata.
  • Constructs a minimal FROM scratch final image containing only the necessary files and symlinks (via busybox --install).
  • This variant uses musl-libc and benefits from Alpine's timely security patches.

• Documentation:

  • Updated README.md to include details about the new prom/busybox:alpine tag.
  • Updated Makefile to include alpine in build, push, and manifest targets for all supported architectures (amd64, armv7, arm64, riscv64, ppc64le, s390x).

Motivation

The addition of the Alpine-based image allows consumers to use a static busybox binary with a smaller footprint and faster security updates compared to the existing glibc/uclibc variants.

Similar pull requests

• Update build #63
• Update images #60
• Use busybox from alpine #51

[SuperQ]

I would prefer to split the alpine work from the CI improvements.

[maxhuebler]

I would prefer to split the alpine work from the CI improvements.

Sure, I removed the CI improvements and only left alpine-specific changes. However, I did leave the fix for the build failure.

[SuperQ]

I meant that I want to just fix the build failure first. The. Do the alpine change separately.

[maxhuebler]

I meant that I want to just fix the build failure first. The. Do the alpine change separately.

Ah okay, sure I'll create a new PR with just the build failure fix first.

Edit: Created PR #67