add sharing=locked

Dockerfile

@@ -1,3 +1,13 @@
+# syntax=docker/dockerfile:1.3
+
+# testing with https://github.com/moby/buildkit/issues/1673#issuecomment-698361687
+# docker rm -f buildx_buildkit_localbuild0 ; docker buildx create --use --name localbuild  && docker buildx inspect localbuild --bootstrap && docker rm -f buildx_buildkit_localbuild0 && docker run --privileged -d --name=buildx_buildkit_localbuild0 -v=/dev/shm/buildkit:/var/lib/buildkit moby/buildkit:buildx-stable-1
+## docker buildx create --use --name localbuild
+## docker buildx inspect localbuild --bootstrap
+# recreate buildkit with host path
+## docker rm -f buildx_buildkit_localbuild0
+## docker run --privileged -d --name=buildx_buildkit_localbuild0 -v=/tmp/buildkit:/var/lib/buildkit moby/buildkit:buildx-stable-1
+
 
 # build it with: docker build . -t vodafone-station-exporter
 # run it with: docker run --rm -d --restart unless-stopped -p 9420:9420 -e VF_STATION_PASS=<password> -e VF_STATION_URL=http://192.168.0.1 vodafone-station-exporter
@@ -6,13 +16,23 @@
 FROM golang:1.18-alpine as builder
 ADD . /go/vodafone-station-exporter
 WORKDIR /go/vodafone-station-exporter
+
+RUN apk add file #
+
 # -ldflags="-s -w" for Shrinking Go executables, https://itnext.io/shrinking-go-executable-9e9c17b47a41
-RUN --mount=type=cache,id=gomod,target=/go/pkg/mod \
-    --mount=type=cache,id=gobuild,target=/root/.cache/go-build \
-    go mod download
-RUN --mount=type=cache,id=gomod,target=/go/pkg/mod \
-    --mount=type=cache,id=gobuild,target=/root/.cache/go-build \
-    go build -ldflags="-s -w"
+RUN --mount=type=cache,id=gomod,sharing=locked,mode=0775,target=/go/pkg/mod \
+    --mount=type=cache,id=gobuild,sharing=locked,mode=0775,target=/root/.cache/go-build \
+    go env GOCACHE && \
+    du -hd0 $(go env GOCACHE) && \
+    go mod download && \
+    du -hd0 $(go env GOCACHE)
+RUN --mount=type=cache,id=gomod,sharing=locked,mode=0775,target=/go/pkg/mod \
+    --mount=type=cache,id=gobuild,sharing=locked,mode=0775,target=/root/.cache/go-build \
+    go env GOCACHE && \
+    du -hd0 $(go env GOCACHE) && \
+    GODEBUG=gocachehash=1 go build -v -ldflags="-s -w" && \
+    du -hd0 $(go env GOCACHE)
+   # go build -ldflags="-s -w"
 
 FROM alpine:3.16
 WORKDIR /app