docker: add static build examples

Signed-off-by: deadprogram <[email protected]>

Dockerfile-static

@@ -1,19 +1,20 @@
 # to build this docker image:
-#   docker build -f Dockerfile-static -t gocv-static .
+#   docker buildx build -f Dockerfile-static -t gocv-static --platform=linux/amd64,linux/arm64 .
 #
-FROM ghcr.io/hybridgroup/opencv:4.10.0-static AS gocv-build
+FROM --platform=$BUILDPLATFORM ghcr.io/hybridgroup/opencv:4.10.0-static AS gocv-build
 
 ENV GOPATH /go
 
 COPY . /go/src/gocv.io/x/gocv/
 
 WORKDIR /go/src/gocv.io/x/gocv
 
-RUN ls -la /usr/local/lib/opencv4/3rdparty/
+RUN --mount=target=. \
+    --mount=type=cache,target=/root/.cache/go-build \
+    --mount=type=cache,target=/go/pkg/mod \
+    go build -tags static -o /build/gocv_version ./cmd/version/
 
-RUN go build -tags static -o /build/gocv_version ./cmd/version/
-
-FROM ubuntu:latest AS final
+FROM debian:bullseye AS final
 
 COPY --from=gocv-build /build/gocv_version /run/gocv_version
 

Dockerfile-static-builder

@@ -1,9 +1,11 @@
 # to build this docker image:
 #   docker build -f Dockerfile-static-builder -t gocv-static-builder .
+# or for multi-arch builds:
+#   docker buildx build -f Dockerfile-static-builder -t gocv-static-builder --platform=linux/amd64,linux/arm64 .
 #
 # to use this docker image:
 #   cd /path/to/my/project
-#   docker run --rm -e "BINARYNAME=myapp" -e "SRCPATH=./cmd/mycmd" -v $(pwd):/src -v $(pwd)/build:/build -a stdout -a stderr gocv-static-builder
+#   docker run --rm -e "BINARYNAME=myapp" -e "SRCPATH=./cmd/mycmd" -v $(pwd):/src -v $(pwd)/build:/build -a stdout -a stderr --platform=linux/arm64 gocv-static-builder
 #
 # NOTE that you cannot use highgui from the static build!
 #