Use native ARM builder for aarch64 image (#251)

* Use native ARM builder for aarch64 image

* Don't pin builder arch, remove unsupported architectures from Dockerfile

Author: sairon

.github/workflows/builder.yml

@@ -46,14 +46,18 @@ jobs:
   build:
     name: Build ${{ matrix.arch }} plugin
     needs: init
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.runs-on }}
     permissions:
       contents: read
       packages: write
       id-token: write
     strategy:
       matrix:
         arch: ${{ fromJson(needs.init.outputs.architectures) }}
+        include:
+          - runs-on: ubuntu-24.04
+          - arch: aarch64
+            runs-on: ubuntu-24.04-arm
     steps:
     - name: Checkout the repository
       uses: actions/checkout@v6.0.2
@@ -73,6 +77,7 @@ jobs:
     - name: Build plugin
       uses: home-assistant/builder@2025.11.0
       with:
+        image: ${{ matrix.arch }}
         args: |
           $BUILD_ARGS \
           --${{ matrix.arch }} \

Dockerfile

@@ -1,6 +1,6 @@
 ARG BUILD_FROM
 
-FROM --platform=amd64 golang:1.24-alpine3.22 AS builder
+FROM golang:1.24-alpine3.22 AS builder
 
 WORKDIR /workspace/observer-plugin
 ARG BUILD_ARCH
@@ -9,14 +9,8 @@ COPY . .
 
 # Build
 RUN \
-        if [ "${BUILD_ARCH}" = "armhf" ]; then \
-            CGO_ENABLED=0 GOARM=6 GOARCH=arm go build -ldflags="-s -w"; \
-        elif [ "${BUILD_ARCH}" = "armv7" ]; then \
-            CGO_ENABLED=0 GOARM=7 GOARCH=arm go build -ldflags="-s -w"; \
-        elif [ "${BUILD_ARCH}" = "aarch64" ]; then \
+        if [ "${BUILD_ARCH}" = "aarch64" ]; then \
             CGO_ENABLED=0 GOARCH=arm64 go build -ldflags="-s -w"; \
-        elif [ "${BUILD_ARCH}" = "i386" ]; then \
-            CGO_ENABLED=0 GOARCH=386 go build -ldflags="-s -w"; \
         elif [ "${BUILD_ARCH}" = "amd64" ]; then \
             CGO_ENABLED=0 GOARCH=amd64 go build -ldflags="-s -w"; \
         else \