makefile: add build-image that more directly wraps build-image script

The build-*{server,ad-server,client,toolbox} rules are good for humans
and discoverability but are a bit too rigid for how we want to work with
matrix builds in automation. Add a new build-image rule that more
directly wraps the build-image tool and so that it becomes fairly easy
to directly pass the four primary inputs to the tool (kind, package
source, distro base (aka OS), and arch).

Signed-off-by: John Mulligan <[email protected]>

Author: phlogistonjohn

Makefile

@@ -37,6 +37,7 @@ BUILDFILE_AD_SERVER=$(shell $(call _BUILD_KP,ad-server,default,--print-buildfile
 BUILDFILE_NIGHTLY_AD_SERVER=$(shell $(call _BUILD_KP,ad-server,nightly,--print-buildfile))
 BUILDFILE_CLIENT=$(shell $(call _BUILD_KP,client,default,--print-buildfile))
 BUILDFILE_TOOLBOX=$(shell $(call _BUILD_KP,toolbox,default,--print-buildfile))
+DYN_BUILDFILE=$(shell $(call _BUILD_KP,$(KIND),$(if $(PACKAGE_SOURCE),$(PACKAGE_SOURCE),default),--print-buildfile) 2>/dev/null || echo invalid)
 
 REPO_BASE=quay.io/samba.org/
 
@@ -77,6 +78,13 @@ debug-vars:
 
 ### Image Build and Push Rules ###
 
+build-image: $(DYN_BUILDFILE)
+.PHONY: build-image
+
+$(DYN_BUILDFILE):
+	@[ "$(KIND)" ] || (echo "KIND must be specfied"; exit 1)
+	$(call _BUILD_KP,$(KIND),$(if $(PACKAGE_SOURCE),$(PACKAGE_SOURCE),default)) $(EXTRA_BUILD_ARGS)
+
 build-server: $(BUILDFILE_SERVER)
 .PHONY: build-server
 $(BUILDFILE_SERVER): Makefile $(SERVER_SRC_FILE) $(SERVER_SOURCES)