GitHub Actions cross

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

.github/workflows/build.yml

@@ -14,6 +14,7 @@ on:
 env:
   REPO_SLUG_ORIGIN: "moby/buildkit:master"
   CACHEKEY_BINARIES: "binaries"
+  PLATFORMS: "linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64,linux/s390x,linux/ppc64le"
 
 jobs:
   base:
@@ -82,9 +83,40 @@ jobs:
         env:
           TEST_COVERAGE: 1
           TESTFLAGS: -v --parallel=6 --timeout=20m
-          CACHEDIR_FROM: /tmp/.buildkit-cache/${{ env.CACHEKEY_BINARIES }}
+          CACHEDIR_FROM: /tmp/.buildx-cache/${{ env.CACHEKEY_BINARIES }}
       -
         name: Send to Codecov
         uses: codecov/codecov-action@v1
         with:
           file: ./coverage/coverage.txt
+
+  cross:
+    runs-on: ubuntu-latest
+    needs: [base]
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v2
+      -
+        name: Cache ${{ env.CACHEKEY_BINARIES }}
+        uses: actions/cache@v2
+        with:
+          path: /tmp/.buildx-cache/${{ env.CACHEKEY_BINARIES }}
+          key: ${{ runner.os }}-buildx-${{ env.CACHEKEY_BINARIES }}-${{ github.sha }}
+          restore-keys: |
+            ${{ runner.os }}-buildx-${{ env.CACHEKEY_BINARIES }}-
+      -
+        name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+      -
+        name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+        with:
+          driver-opts: image=${{ env.REPO_SLUG_ORIGIN }}
+      -
+        name: Cross
+        run: |
+          make cross
+        env:
+          TARGETPLATFORM: ${{ env.PLATFORMS }},darwin/amd64,windows/amd64
+          CACHEDIR_FROM: /tmp/.buildx-cache/${{ env.CACHEKEY_BINARIES }}