dockerfile: add registry to base image specifier & force flag to `rm`; makefile: added "podman-build" target

https://github.com/fphammerle/switchbot-mqtt/commit/82eb01a3d4049a6eac9cd0f4b6b97e2acfec6f90
https://github.com/fphammerle/switchbot-mqtt/commit/1c60b96a53bbbcc11b99fd34f0ecc91cb423b7e7

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.11 as download
+FROM docker.io/alpine:3.11 as download
 RUN apk add --no-cache git
 USER nobody
 # 0.2.200 (update Makefile)
@@ -6,14 +6,14 @@ ARG MONITOR_VERSION=1deec402b9b6323a964381819b199300259bb584
 RUN git clone https://github.com/andrewjfreyer/monitor /tmp/monitor
 WORKDIR /tmp/monitor
 RUN git checkout $MONITOR_VERSION \
-    && rm -r .git .gitignore
+    && rm -rf .git .gitignore
 # workaround for broken multi-stage copy
 # > failed to copy files: failed to copy directory: Error processing tar file(exit status 1): Container ID ... cannot be mapped to a host ID
 USER 0
 RUN chown -R 0:0 . \
     && chmod a+rX -R -c .
 
-FROM alpine:3.11
+FROM docker.io/alpine:3.11
 RUN apk add --no-cache \
         bash \
         bluez-btmon \

Makefile

@@ -12,12 +12,17 @@ DOCKER_TAG_ARCH_SUFFIX_x86_64 := amd64
 DOCKER_TAG_ARCH_SUFFIX = ${DOCKER_TAG_ARCH_SUFFIX_${ARCH}}
 DOCKER_TAG = ${DOCKER_TAG_VERSION}-monitor${MONITOR_VERSION}-${DOCKER_TAG_ARCH_SUFFIX}
 
-.PHONY: docker-build docker-push
+.PHONY: docker-build podman-build docker-push
 
 docker-build:
 	git diff --exit-code
 	git diff --staged --exit-code
-	sudo docker build -t "${DOCKER_IMAGE_NAME}:${DOCKER_TAG}" .
+	sudo docker build --tag="${DOCKER_IMAGE_NAME}:${DOCKER_TAG}" .
+
+podman-build:
+	# --format=oci (default) not fully supported by hub.docker.com
+	# https://github.com/docker/hub-feedback/issues/1871#issuecomment-748924149
+	podman build --format=docker --tag="${DOCKER_IMAGE_NAME}:${DOCKER_TAG}" .
 
 docker-push: docker-build
 	sudo docker push "${DOCKER_IMAGE_NAME}:${DOCKER_TAG}"