Enable check for presence of carvel toolset

The packaging make targets depend on the carvel tools to be present.
This enables the check to make sure they are there before running some
of the targets that attempt to use them.

Signed-off-by: Sean McGinnis <smcginnis@vmware.com>

Makefile

@@ -10,7 +10,7 @@ else
 	NUL = /dev/null
 endif
 
-#REQUIRED_BINARIES := imgpkg kbld ytt
+REQUIRED_BINARIES := imgpkg kbld ytt
 
 TOOLS_DIR := hack/tools
 TOOLS_BIN_DIR := $(TOOLS_DIR)/bin
@@ -158,10 +158,6 @@ release-docker: release-env-check ## builds and produces the release packaging/t
 
 clean: clean-release clean-plugin clean-core
 
-#check-carvel:
-#	K := $(foreach exec,$(REQUIRED_BINARIES),\
-#		$(if $(shell which $(exec)),placeholder,$(error "No $(exec) See instructions at https://carvel.dev\#install")))
-
 release-env-check:
 ifndef GH_ACCESS_TOKEN
 	$(error GH_ACCESS_TOKEN is undefined)
@@ -265,33 +261,37 @@ create-channel: # Stub out new channel values file. Usage: make create-channel N
 
 ##### PACKAGE OPERATIONS #####
 
-vendir-sync-all: # Performs a `vendir sync` for each package
+check-carvel:
+	$(foreach exec,$(REQUIRED_BINARIES),\
+		$(if $(shell which $(exec)),placeholder,$(error "'$(exec)' not found. Carvel toolset is required. See instructions at https://carvel.dev/#install")))
+
+vendir-sync-all: check-carvel # Performs a `vendir sync` for each package
 	@cd addons/packages && for package in *; do\
 		printf "\n===> syncing $${package}\n";\
 		pushd $${package}/bundle;\
 		vendir sync >> /dev/null;\
 		popd;\
 	done
 
-vendir-sync-package: # Performs a `vendir sync` for a package. Usage: make vendir-package-sync PACKAGE=foobar
+vendir-sync-package: check-carvel # Performs a `vendir sync` for a package. Usage: make vendir-package-sync PACKAGE=foobar
 	@printf "\n===> syncing $${PACKAGE}\n";\
 	cd addons/packages/$${PACKAGE}/bundle && vendir sync >> /dev/null;\
 
-lock-images-all: # Updates the image lock file in each package.
+lock-images-all: check-carvel # Updates the image lock file in each package.
 	@cd addons/packages && for package in *; do\
 		printf "\n===> Updating image lockfile for package $${package}\n";\
 		kbld --file $${package}/bundle --imgpkg-lock-output $${package}/bundle/.imgpkg/images.yml >> /dev/null;\
 	done
 
-lock-package-images: # Updates the image lock file for a package. Usage: make lock-package-images PACKAGE=foobar
+lock-package-images: check-carvel # Updates the image lock file for a package. Usage: make lock-package-images PACKAGE=foobar
 	@printf "\n===> Updating image lockfile for package $${PACKAGE}\n";\
 	cd addons/packages/$${PACKAGE} && kbld --file bundle --imgpkg-lock-output bundle/.imgpkg/images.yml >> /dev/null;\
 
-push-package: # Build and push a package template. Tag will default to `latest`. Usage: make push-package PACKAGE=foobar TAG=baz
+push-package: check-carvel # Build and push a package template. Tag will default to `latest`. Usage: make push-package PACKAGE=foobar TAG=baz
 	@printf "\n===> pushing $${PACKAGE}\n";\
 	cd addons/packages/$${PACKAGE} && imgpkg push --bundle $(OCI_REGISTRY)/$${PACKAGE}:$${TAG} --file bundle/;\
 
-push-package-all: # Build and push all package templates. Tag will default to `latest`. Usage: make push-package-all TAG=baz
+push-package-all: check-carvel # Build and push all package templates. Tag will default to `latest`. Usage: make push-package-all TAG=baz
 	@cd addons/packages && for package in *; do\
 		printf "\n===> pushing $${package}\n";\
 		imgpkg push --bundle $(OCI_REGISTRY)/$${package}:$${TAG} --file $${package}/bundle/;\
@@ -303,11 +303,11 @@ update-package: vendir-sync-package lock-package-images push-package # Perform a
 update-package-all: vendir-sync-all lock-images push-package-all # Perform all the steps to update all packages. Tag will default to `latest`. Usage: make update-package-all TAG=baz
 	@printf "\n===> updated packages\n";\
 
-update-package-repo: # Update the repository metadata. CHANNEL will default to `alpha`. REPO_TAG will default to `stable` Usage: make update-package-repo OCI_REGISTRY=repo.example.com/foo CHANNEL=beta REPO_TAG=0.3.5
+update-package-repo: check-carvel # Update the repository metadata. CHANNEL will default to `alpha`. REPO_TAG will default to `stable` Usage: make update-package-repo OCI_REGISTRY=repo.example.com/foo CHANNEL=beta REPO_TAG=0.3.5
 	@printf "\n===> updating repository metadata\n";\
 	imgpkg push -i ${OCI_REGISTRY}/${CHANNEL}:$${REPO_TAG} -f addons/repos/generated/${CHANNEL};\
 
-generate-package-metadata: # Usage: make generate-package-metadata OCI_REGISTRY=repo.example.com/foo CHANNEL=alpha REPO_TAG=0.4.1
+generate-package-metadata: check-carvel # Usage: make generate-package-metadata OCI_REGISTRY=repo.example.com/foo CHANNEL=alpha REPO_TAG=0.4.1
 	@printf "\n===> Generating package metadata for $${CHANNEL}\n";\
     stat addons/repos/$${CHANNEL}.yaml &&\
 	CHANNEL_DIR=addons/repos/generated/$${CHANNEL} &&\
@@ -318,7 +318,7 @@ generate-package-metadata: # Usage: make generate-package-metadata OCI_REGISTRY=
 	echo "\nRun the following command to push this imgpkgBundle to your OCI registry:\n\timgpkg push -b ${OCI_REGISTRY}/${CHANNEL}:$${REPO_TAG} -f $${CHANNEL_DIR}\n" &&\
 	echo "Use the URL returned from \`imgpkg push\` in the values file (\`package_repository.imgpkgBundle\`) for this channel.";\
 
-generate-package-repository-metadata: # Usage: make generate-package-repository-metadata CHANNEL=alpha
+generate-package-repository-metadata: check-carvel # Usage: make generate-package-repository-metadata CHANNEL=alpha
 	@printf "\n===> Generating package repository metadata for $${CHANNEL}\n";\
     stat addons/repos/$${CHANNEL}.yaml &&\
 	ytt -f addons/repos/overlays/package-repository.yaml -f addons/repos/$${CHANNEL}.yaml > addons/repos/generated/$${CHANNEL}-package-repository.yaml &&\