*: build a limited version of rkt on non-Linux

This introduces build tags to allow the actual rkt binary to be built on
platforms other than Linux. This does not change our current focus of rocket
being targeted at the Linux/amd64 platform, but means that users on e.g.
OS X and other operating systems can at least use `rkt fetch` to
retrieve ACI images and so forth.

build

@@ -19,29 +19,30 @@ go build -o $GOBIN/actool ${REPO_PATH}/app-container/actool
 echo "Building ACE validator..."
 GOOS=linux CGO_ENABLED=0 go build -a -ldflags '-extldflags "-static"' -o $GOBIN/ace-validator ${REPO_PATH}/app-container/ace
 
-echo "Building init (stage1)..."
-go build -o $GOBIN/init ${REPO_PATH}/stage1
+if [[ "$OSTYPE" == "linux-gnu" ]]; then
+	echo "Building init (stage1)..."
+	go build -o $GOBIN/init ${REPO_PATH}/stage1
 
-S1BINS=${PWD}/stage0
-S1INIT=${S1BINS}/stage1_init
-if [ $GOBIN/init -nt $S1INIT/bin.go ]; then
-	echo "Packaging init (stage1)..."
-	TMP=$(mktemp -d)
-	[ -d $S1INIT ] || mkdir -p $S1INIT
-	cp $GOBIN/init $TMP/s1init
-	go-bindata -o $S1INIT/bin.go -pkg="stage1_init" -prefix=$TMP $TMP
+	S1BINS=${PWD}/stage0
+	S1INIT=${S1BINS}/stage1_init
+	if [ $GOBIN/init -nt $S1INIT/bin.go ]; then
+		echo "Packaging init (stage1)..."
+		TMP=$(mktemp -d)
+		[ -d $S1INIT ] || mkdir -p $S1INIT
+		cp $GOBIN/init $TMP/s1init
+		go-bindata -o $S1INIT/bin.go -pkg="stage1_init" -prefix=$TMP $TMP
+	fi
+
+	S1ROOTFS=${S1BINS}/stage1_rootfs
+	if [ stage1/mkrootfs.sh -nt $S1ROOTFS/bin.go ]; then
+		echo "Generating and packaging rootfs (stage1)..."
+		[ -d "${S1ROOTFS}" ] || mkdir -p "${S1ROOTFS}"
+		pushd stage1
+		OUTPUT=$S1ROOTFS/bin.go ./mkrootfs.sh
+		popd
+	fi
 fi
 
-S1ROOTFS=${S1BINS}/stage1_rootfs
-if [ stage1/mkrootfs.sh -nt $S1ROOTFS/bin.go ]; then
-	echo "Generating and packaging rootfs (stage1)..."
-	[ -d "${S1ROOTFS}" ] || mkdir -p "${S1ROOTFS}"
-	pushd stage1
-	OUTPUT=$S1ROOTFS/bin.go ./mkrootfs.sh
-	popd
-fi
-
-
 echo "Building rkt (stage0)..."
 go build -o $GOBIN/rkt ${REPO_PATH}/rkt
 

rkt/run_linux.go

@@ -1,3 +1,5 @@
+//+build linux
+
 package main
 
 import (

rkt/run_other.go

@@ -0,0 +1,18 @@
+//+build !linux
+
+package main
+
+import "fmt"
+
+var (
+	cmdRun = &Command{
+		Name:    "run",
+		Summary: "Run image(s) in an application container in rocket",
+		Run:     runRun,
+	}
+)
+
+func runRun(args []string) (exit int) {
+	fmt.Println("run is not implemented on this platform.")
+	return
+}

rkt/status_linux.go

@@ -1,3 +1,5 @@
+//+build linux
+
 package main
 
 import "fmt"

rkt/status_other.go

@@ -0,0 +1,18 @@
+//+build !linux
+
+package main
+
+import "fmt"
+
+var (
+	cmdStatus = &Command{
+		Name:    "status",
+		Summary: "Check the status of a rkt job",
+		Run:     runStatus,
+	}
+)
+
+func runStatus(args []string) (exit int) {
+	fmt.Println("status is not implemented on this platform.")
+	return
+}

stage0/run.go

@@ -1,3 +1,5 @@
+//+build linux
+
 package stage0
 
 //

stage1/container.go

@@ -1,3 +1,5 @@
+//+build linux
+
 package main
 
 import (

stage1/init.go

@@ -1,3 +1,5 @@
+//+build linux
+
 package main
 
 // this implements /init of stage1/nspawn+systemd

stage1/path.go

@@ -1,3 +1,5 @@
+//+build linux
+
 package main
 
 import (