Update build for cross-compiling using CGO

See: https://oddcode.daveamit.com/2018/08/17/embed-versioning-information-in-golang-binary/

build.sh

@@ -0,0 +1,101 @@
+#!/bin/bash
+
+APP=mqttListener
+
+# expand PATH for go tools
+export PATH=$PATH:~/go/bin
+
+
+RED='\e[0;31m'
+GREEN='\e[0;32m'
+LIGHT_YELLOW='\e[93m'
+NC='\e[0m' # No Color
+BOLD='\e[1m'
+NORMAL='\e[21m'
+
+#######################################################################################
+# defaults
+GO_BUILD_OPTIONS=-v
+#GO_BUILD_OPTIONS="-a -v"
+DEFAULT_TARGET=amd64
+
+#######################################################################################
+# functions
+
+die() { echo -e "\n${RED}$@${NC}" 1>&2 ; exit 1; }
+
+usage() {
+  echo "usage: `basename $0` [<TARGET>] [all]"
+}
+
+
+#######################################################################################
+# build functions
+
+build_linux_amd64() {
+    echo -e "\nBuilding for Linux amd64:"
+    
+    env GOOS=linux GOARCH=amd64 go build ${GO_BUILD_OPTIONS} -ldflags "$(govvv -flags)" -o ${APP}-linux-amd64
+    echo -e "\t\t${GREEN}... done${NC}"
+}
+
+build_linux_arm() {
+    echo -e "\nBuilding for arm:"
+    
+    # setup environment
+    export CGO_ENABLED=1
+    export PATH=$PATH:/opt/devel/ptu4/buildrootBuild/host/usr/bin
+    export CC=arm-linux-gcc
+    export PKG_CONFIG_PATH=/opt/devel/ptu4/buildrootBuild/host/usr/lib/pkgconfig
+    
+    env GOOS=linux GOARCH=arm go build ${GO_BUILD_OPTIONS} -ldflags "$(govvv -flags)" -o ${APP}-linux-arm
+    echo -e "\t\t${GREEN}... done${NC}"
+
+    echo -e "\nstipping arm binary:"
+    strip -o ${TARGET}-linux-arm-stripped ${APP}-linux-arm
+    echo -e "\t\t${GREEN}... done${NC}"
+}
+
+#######################################################################################
+# checks
+
+echo -e "${NC}\n "
+
+
+if [ ! command -v govvv &> /dev/null ] ; then
+    die "govvv is not installed"	
+fi	
+
+
+if [ $# -eq 0 ] ; then
+    echo -e "\nbuilding for default TARGET ${DEFAULT_TARGET}..."
+    TARGET=${DEFAULT_TARGET}
+else
+    TARGET=$1
+fi
+
+#######################################################################################
+# build
+
+#cd /src
+
+
+if [ "$2" == "all" ] ; then
+    echo -e "\nforce rebuilding of all packages..."
+    GO_BUILD_OPTIONS="-a -v"
+fi
+
+
+case "${TARGET}" in
+"arm"|"ARM")
+    build_linux_arm
+    ;;
+"amd64"|"AMD64")
+    build_linux_amd64
+    ;;
+*)
+    usage
+    die "Target ${TARGET} is not defined"
+    ;;
+esac
+

go.mod

@@ -3,6 +3,7 @@ module mqttListener
 go 1.14
 
 require (
+	github.com/ahmetb/govvv v0.3.0 // indirect
 	github.com/eclipse/paho.mqtt.golang v1.2.0
 	github.com/mattn/go-sqlite3 v1.14.2
 	github.com/mmcdole/gofeed v1.0.0

main.go

@@ -6,18 +6,64 @@ import (
 	"mqttListener/models"
 	"mqttListener/mqtt"
 
+	"flag"
 	"fmt"
 	"log"
 
 	"os"
 	"os/signal"
+	"path/filepath"
 	"syscall"
 
 	"net/http"
 )
 
+// ---------------------------------------------------------------------------
+// Following variables will be statically linked at the time of compiling
+
+// GitCommit holds short commit hash of source tree
+var GitCommit string
+
+// GitBranch holds current branch name the code is built off
+var GitBranch string
+
+// GitState shows whether there are uncommitted changes
+var GitState string
+
+// GitSummary holds output of git describe --tags --dirty --always
+var GitSummary string
+
+// BuildDate holds RFC3339 formatted UTC date (build time)
+var BuildDate string
+
+// Version holds contents of ./VERSION file, if exists, or the value passed via the -version option
+var Version string
+
+// PrintVersion prints version information
+func PrintVersion() {
+	var versionString string = GitSummary
+	fmt.Println("\n--------------------------------------------------------")
+	fmt.Println(filepath.Base(os.Args[0]), " Version Information: ")
+	fmt.Println("\tVersion:\t", versionString)
+	fmt.Println("\tBranch:\t\t", GitBranch)
+	fmt.Println("\tCommit-ID:\t", GitCommit)
+	fmt.Println("\tBuilt:\t\t", BuildDate)
+	fmt.Println("\n--------------------------------------------------------")
+	fmt.Println("")
+}
+
+// ---------------------------------------------------------------------------
 func main() {
 
+	versionFlagPtr := flag.Bool("v", false, "print version")
+	flag.Parse()
+	if *versionFlagPtr {
+		PrintVersion()
+		os.Exit(0)
+	}
+
+	PrintVersion()
+
 	c := make(chan os.Signal, 1)
 	signal.Notify(c, os.Interrupt, syscall.SIGTERM)
 
@@ -34,7 +80,7 @@ func main() {
 		log.Panic(err)
 	}
 
-	env := &env.Env{db, config}
+	env := &env.Env{DB: db, Config: config}
 
 	mqtt.Setup(env)
 	mqtt.Connect()