Build only when files get changed

Makefile

@@ -4,8 +4,9 @@ IMAGE_NAME := mysql-operator
 SIDECAR_IMAGE_NAME := mysql-operator-sidecar
 BUILD_TAG := build
 IMAGE_TAGS := $(APP_VERSION)
+PKG_NAME := github.com/presslabs/mysql-operator
 
-BINDIR := bin
+BINDIR := $(PWD)/bin
 KUBEBUILDER_VERSION ?= 1.0.7
 HELM_VERSION ?= 2.11.0
 
@@ -33,9 +34,14 @@ build: generate fmt vet
 	go build -o bin/mysql-operator github.com/presslabs/mysql-operator/cmd/mysql-operator
 	go build -o bin/mysql-operator-sidecar github.com/presslabs/mysql-operator/cmd/mysql-operator-sidecar
 
-skaffold-build:
-	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -a -o $(BINDIR)/mysql-operator_linux_amd64 github.com/presslabs/mysql-operator/cmd/mysql-operator
-	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -a -o $(BINDIR)/mysql-operator-sidecar_linux_amd64 github.com/presslabs/mysql-operator/cmd/mysql-operator-sidecar
+bin/mysql-operator_linux_amd64: $(shell hack/development/related-go-files.sh $(PKG_NAME) cmd/mysql-operator/main.go)
+	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -a -o bin/mysql-operator_linux_amd64 github.com/presslabs/mysql-operator/cmd/mysql-operator
+
+bin/mysql-operator-sidecar_linux_amd64: $(shell hack/development/related-go-files.sh $(PKG_NAME) cmd/mysql-operator-sidecar/main.go)
+	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -a -o bin/mysql-operator-sidecar_linux_amd64 github.com/presslabs/mysql-operator/cmd/mysql-operator-sidecar
+
+skaffold-run: bin/mysql-operator_linux_amd64 bin/mysql-operator-sidecar_linux_amd64
+	skaffold run
 
 # Run against the configured Kubernetes cluster in ~/.kube/config
 run: generate fmt vet

hack/development/related-go-files.sh

@@ -0,0 +1,5 @@
+#!/bin/bash
+set -e
+
+# This command outputs a list of go files on which the given go file depends on
+go list -f '{{ join .Deps "\n" }}' $2 | grep 'pkg' | grep -v 'vendor' | sed -e "s|^$1/||" | xargs -I % find % -name "*.go" -maxdepth 1 -type f 2>/dev/null