build: Pre-pull FROM images with DOCKER_BUIDKIT

[ upstream commit ae5d7c1 ]

Docker buildkit often fails to actaully pull the FROM image and then
fails wit errors like:

 > [builder 4/4] RUN make ... clean-container build-container install-container:
#13 0.344 /bin/sh: 1: make: not found

Fix this by pulling all FROM images before docker build. This depends
on the FROM image names not be based on build ARGs, which is the case
for all the current Dockerfiles in the repo.

Fixes: #11513
Signed-off-by: Jarno Rajahalme <jarno@covalent.io>
Signed-off-by: André Martins <andre@cilium.io>

Makefile.buildkit

@@ -64,6 +64,7 @@ _build/context/BPF_SRCFILES: BPF_SRCFILES _build/context
 _build/%ockerfile: %ockerfile force
 	@-mkdir -p $(dir $@)
 	@cat $< $(BUILDKIT_DOCKERFILE_FILTER) > $@
+	@-grep "^FROM " $@ | cut -d ' ' -f2 | grep -v "scratch" | xargs -P4 -n1 docker pull
 
 check-status:
 	@if [ -n "`git status --porcelain`" ] ; then git status && echo "These changes will not be included in build, aborting. Define IGNORE_GIT_STATUS to build anyway." && test $(IGNORE_GIT_STATUS); fi