Add docker-localnet.yml workflow

Author: Roman

.github/workflows/docker-localnet.yml

@@ -0,0 +1,71 @@
+name: Publish Localnet Docker Image
+
+on:
+  release:
+    types: [published]
+  workflow_dispatch:
+    inputs:
+      branch-or-tag:
+        description: "Branch or tag to use for the Docker image tag and ref to checkout (optional)"
+        required: false
+        default: ""
+  push:
+    branches:
+      - devnet-ready
+      - devnet
+      - testnet
+
+permissions:
+  contents: read
+  packages: write
+  actions: read
+  security-events: write
+
+jobs:
+  publish:
+    runs-on: SubtensorCI
+
+    steps:
+      - name: Determine Docker tag and ref
+        id: tag
+        run: |
+          branch_or_tag="${{ github.event.inputs.branch-or-tag || github.ref_name }}"
+          echo "Determined branch or tag: $branch_or_tag"
+          echo "tag=$branch_or_tag" >> $GITHUB_ENV
+          echo "ref=$branch_or_tag" >> $GITHUB_ENV
+
+          # Check if this is a tagged release (not devnet-ready/devnet/testnet)
+          if [[ "$branch_or_tag" != "devnet-ready" ]]; then
+            echo "latest_tag=true" >> $GITHUB_ENV
+          else
+            echo "latest_tag=false" >> $GITHUB_ENV
+          fi
+
+      - name: Checkout code
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ env.ref }}
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
+      - name: Login to GHCR
+        uses: docker/login-action@v2
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v4
+        with:
+          context: .
+          file: Docker-localnet
+          push: true
+          platforms: linux/amd64,linux/arm64
+          tags: |
+            ghcr.io/${{ github.repository }}-localnet:${{ env.tag }}
+            ${{ env.latest_tag == 'true' && format('ghcr.io/{0}-localnet:latest', github.repository) || '' }}