Fix Dockerfile warnings (#574)

Dockerfile

@@ -1,5 +1,5 @@
 # Build the manager binary
-FROM golang:1.23rc2-bookworm as builder
+FROM golang:1.23rc2-bookworm AS builder
 
 WORKDIR /workspace
 # Copy the Go Modules manifests
@@ -20,14 +20,14 @@ COPY hack/ hack/
 ARG TARGETOS
 ARG TARGETARCH
 
-FROM builder as ceph-bucket-provider-builder
+FROM builder AS ceph-bucket-provider-builder
 RUN --mount=type=cache,target=/root/.cache/go-build \
     --mount=type=cache,target=/go/pkg \
     CGO_ENABLED=0 GOOS=$TARGETOS GOARCH=$TARGETARCH GO111MODULE=on go build -ldflags="-s -w" -a -o bin/ceph-bucket-provider ./cmd/bucketprovider/main.go
 
 
 # Start from Kubernetes Debian base.
-FROM builder as ceph-volume-provider-builder
+FROM builder AS ceph-volume-provider-builder
 # Install necessary dependencies
 
 RUN apt update  && apt install -y libcephfs-dev librbd-dev librados-dev libc-bin
@@ -40,7 +40,7 @@ RUN --mount=type=cache,target=/root/.cache/go-build \
 
 # Use distroless as minimal base image to package the manager binary
 # Refer to https://github.com/GoogleContainerTools/distroless for more details
-FROM gcr.io/distroless/static:nonroot as manager
+FROM gcr.io/distroless/static:nonroot AS manager
 WORKDIR /
 COPY --from=controller /workspace/bin/manager .
 USER 65532:65532
@@ -50,21 +50,21 @@ ENTRYPOINT ["/manager"]
 
 
 # Since we're leveraging apt to pull in dependencies, we use `gcr.io/distroless/base` because it includes glibc.
-FROM gcr.io/distroless/base-debian11 as distroless-base
+FROM gcr.io/distroless/base-debian11 AS distroless-base
 
 # The distroless amd64 image has a target triplet of x86_64
 FROM distroless-base AS distroless-amd64
-ENV LIB_DIR_PREFIX x86_64
-ENV LIB_DIR_PREFIX_MINUS x86-64
+ENV LIB_DIR_PREFIX=x86_64
+ENV LIB_DIR_PREFIX_MINUS=x86-64
 
 # The distroless arm64 image has a target triplet of aarch64
 FROM distroless-base AS distroless-arm64
-ENV LIB_DIR_PREFIX aarch64
-ENV LIB_DIR_PREFIX_MINUS aarch64
+ENV LIB_DIR_PREFIX=aarch64
+ENV LIB_DIR_PREFIX_MINUS=aarch64
 
 
-FROM busybox:1.36.1-uclibc as busybox
-FROM distroless-$TARGETARCH as ceph-volume-provider-image
+FROM busybox:1.36.1-uclibc AS busybox
+FROM distroless-$TARGETARCH AS ceph-volume-provider-image
 WORKDIR /
 COPY --from=busybox /bin/sh /bin/sh
 COPY --from=busybox /bin/mkdir /bin/mkdir
@@ -97,7 +97,7 @@ COPY --from=ceph-volume-provider-builder /lib/${LIB_DIR_PREFIX}-linux-gnu/librad
 /lib/${LIB_DIR_PREFIX}-linux-gnu/libnl-3.so.200 \
 /lib/${LIB_DIR_PREFIX}-linux-gnu/libselinux.so.1 \
 /lib/${LIB_DIR_PREFIX}-linux-gnu/libpthread.so.0 \
-/lib/${LIB_DIR_PREFIX}-linux-gnu/libpcre2-8.so.0 /lib/${LIB_DIR_PREFIX}-linux-gnu
+/lib/${LIB_DIR_PREFIX}-linux-gnu/libpcre2-8.so.0 /lib/${LIB_DIR_PREFIX}-linux-gnu/
 RUN mkdir -p /lib64
 COPY --from=ceph-volume-provider-builder /lib64/ld-linux-${LIB_DIR_PREFIX_MINUS}.so.2 /lib64/
 RUN mkdir -p /usr/lib/${LIB_DIR_PREFIX}-linux-gnu/ceph/
@@ -107,7 +107,7 @@ COPY --from=ceph-volume-provider-builder /workspace/bin/ceph-volume-provider /ce
 
 # Build stage used for validation of the output-image
 # See validate-container-linux-* targets in Makefile
-FROM ceph-volume-provider-image as validation-image
+FROM ceph-volume-provider-image AS validation-image
 
 COPY --from=busybox /usr/bin/ldd /usr/bin/find /usr/bin/xargs /usr/bin/
 COPY --from=builder /workspace/hack/print-missing-deps.sh /print-missing-deps.sh
@@ -116,14 +116,14 @@ RUN /print-missing-deps.sh
 
 
 # Final build stage, create the real Docker image with ENTRYPOINT
-FROM ceph-volume-provider-image as ceph-volume-provider
+FROM ceph-volume-provider-image AS ceph-volume-provider
 USER 65532:65532
 
 ENTRYPOINT ["/ceph-volume-provider"]
 
 
 
-FROM distroless-base  as ceph-bucket-provider
+FROM distroless-base  AS ceph-bucket-provider
 COPY --from=ceph-bucket-provider-builder /workspace/bin/ceph-bucket-provider /ceph-bucket-provider
 USER 65532:65532
 ENTRYPOINT ["/ceph-bucket-provider"]