Add multiplatform image build/push

Author: lystopad

.github/workflows/testing-docker-multiplatform-builds.yml

@@ -1,12 +1,15 @@
 name: Testing docker multiplatform builds
 run-name: Testing docker multiplatform builds
 
+env:
+  DOCKER_URL: "erigontech/dev-erigon:test-oleksandr"
+
 on:
   workflow_dispatch:
 
 jobs:
 
-  build-architecture:
+  build-archs:
     runs-on: ${{ matrix.runner }}
     timeout-minutes: 15
     strategy:
@@ -40,6 +43,27 @@ jobs:
             --attest type=provenance,mode=max \
             --push --platform linux/${{ matrix.arch }} \
             --progress plain \
-            -t erigontech/dev-erigon:test-oleksandr-${{ matrix.docker-tag }} -f Dockerfile-mp .
+            -t ${{ env.DOCKER_URL }}-${{ matrix.docker-tag }} -f Dockerfile-mp .
 
       
+  build-final-image:
+    runs-on: ubuntu-24.04
+    timeout-minutes: 10
+    steps:
+
+    - name: Login to Docker Hub
+      uses: docker/login-action@v3
+      with:
+        username: ${{ secrets.ORG_DOCKERHUB_ERIGONTECH_USERNAME }}
+        password: ${{ secrets.ORG_DOCKERHUB_ERIGONTECH_TOKEN }}
+
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v3
+
+    - name: Build multiplatform image
+      run: |
+        docker manifest create \
+            ${{ env.DOCKER_URL }} \
+            --amend ${{ env.DOCKER_URL }}-amd64-v2 \
+            --amend ${{ env.DOCKER_URL }}-arm64
+        docker manifest push ${{ env.DOCKER_URL }}