Refactor Makefile (#538)

* Update go-install-tool function

* Remove hardcoded ENVTEST_K8S_VERSION

* Add CONTAINER_TOOL env variable

Author: gonzolino

Makefile

@@ -1,15 +1,21 @@
 BIN_NAME = "cloud-provider-ironcore"
 IMG ?= controller:latest
 
-# ENVTEST_K8S_VERSION refers to the version of kubebuilder assets to be downloaded by envtest binary.
-ENVTEST_K8S_VERSION = 1.32
-
+# Get the currently used golang install path (in GOPATH/bin, unless GOBIN is set)
 ifeq (,$(shell go env GOBIN))
 GOBIN=$(shell go env GOPATH)/bin
 else
 GOBIN=$(shell go env GOBIN)
 endif
 
+# CONTAINER_TOOL defines the container tool to be used for building images.
+# Be aware that the target commands are only tested with Docker which is
+# scaffolded by default. However, you might want to replace it to use other
+# tools. (i.e. podman)
+CONTAINER_TOOL ?= docker
+
+# Setting SHELL to bash allows bash commands to be executed by recipes.
+# Options are set to exit when a recipe line exits non-zero or a piped command fails.
 SHELL = /usr/bin/env bash -o pipefail
 .SHELLFLAGS = -ec
 
@@ -62,14 +68,14 @@ vet: ## Run go vet against code.
 test: fmt vet envtest ## Run tests.
 	KUBEBUILDER_ASSETS="$(shell $(ENVTEST) use $(ENVTEST_K8S_VERSION) --bin-dir $(LOCALBIN) -p path)" go test $$(go list ./... | grep -v /e2e) -coverprofile cover.out
 
-.PHONY: docker-build
 # Build the docker image
-docker-build:
-	docker build . -t $(IMG)
+.PHONY: docker-build
+docker-build: ## Build docker image with the manager.
+	$(CONTAINER_TOOL) build -t ${IMG} .
 
 .PHONY: docker-push
-docker-push:
-	docker push $(IMG)
+docker-push: ## Push docker image with the manager.
+	$(CONTAINER_TOOL) push ${IMG}
 
 .PHONY: clean-local-bin
 clean-local-bin:
@@ -130,13 +136,13 @@ $(GOLANGCI_LINT): $(LOCALBIN)
 # $2 - package url which can be installed
 # $3 - specific version of package
 define go-install-tool
-@[ -f "$(1)-$(3)" ] || { \
+@[ -f "$(1)-$(3)" ] && [ "$$(readlink -- "$(1)" 2>/dev/null)" = "$(1)-$(3)" ] || { \
 set -e; \
 package=$(2)@$(3) ;\
 echo "Downloading $${package}" ;\
-rm -f $(1) || true ;\
+rm -f $(1) ;\
 GOBIN=$(LOCALBIN) go install $${package} ;\
 mv $(1) $(1)-$(3) ;\
 } ;\
-ln -sf $(1)-$(3) $(1)
+ln -sf $$(realpath $(1)-$(3)) $(1)
 endef