Switch runc and containerd startup to be entirely Go

At present they use a small shared function called "prepare"
that does the read-write remounts, that I will switch to doing overlay
mounts soon.

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

pkg/runc/Dockerfile

@@ -1,4 +1,4 @@
-FROM linuxkit/alpine:8bb8664eec04e02a8a131c53aa7d5d94119270ef as alpine
+FROM linuxkit/alpine:a39a433162a873519910a07beeb3e8db22529956 as alpine
 RUN \
   apk add \
   bash \
@@ -10,7 +10,7 @@ RUN \
   linux-headers \
   make \
   && true
-ENV GOPATH=/root/go
+ENV GOPATH=/go PATH=$PATH:/go/bin
 ENV RUNC_COMMIT=429a5387123625040bacfbb60d96b1cbd02293ab
 RUN mkdir -p $GOPATH/src/github.com/opencontainers && \
   cd $GOPATH/src/github.com/opencontainers && \
@@ -20,8 +20,14 @@ RUN git checkout $RUNC_COMMIT
 RUN make static BUILDTAGS="seccomp" EXTRA_FLAGS="-buildmode pie" EXTRA_LDFLAGS="-extldflags \\\"-fno-PIC -static\\\""
 RUN cp runc /usr/bin/
 
+ADD cmd /go/src/cmd
+RUN go-compile.sh /go/src/cmd/onboot
+RUN mkdir -p /etc/init.d && ln -s /usr/bin/onboot /etc/init.d/010-onboot
+RUN mkdir -p /etc/shutdown.d && ln -s /usr/bin/onboot /etc/shutdown.d/010-onshutdown
+
 FROM scratch
 WORKDIR /
 ENTRYPOINT []
-COPY --from=alpine /usr/bin/runc /usr/bin/
-COPY etc etc/
+COPY --from=alpine /usr/bin/runc /go/bin/onboot /usr/bin/
+COPY --from=alpine /etc/init.d/ /etc/init.d/
+COPY --from=alpine /etc/shutdown.d/ /etc/shutdown.d/

pkg/runc/Makefile

@@ -1,5 +1,5 @@
 IMAGE=runc
 NETWORK=1
-DEPS=$(wildcard etc/init.d/*)
+DEPS=$(wildcard cmd/onboot/*.go)
 
 include ../package.mk

pkg/runc/cmd/onboot/main.go

@@ -0,0 +1,63 @@
+package main
+
+import (
+	"io/ioutil"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+)
+
+const (
+	runcBinary   = "/usr/bin/runc"
+	onbootPath   = "/containers/onboot"
+	shutdownPath = "/containers/onshutdown"
+)
+
+func main() {
+	// try to work out how we are being called
+	command := os.Args[0]
+	if len(os.Args) > 1 {
+		command = os.Args[1]
+	}
+	var path = onbootPath
+	switch {
+	case strings.Contains(command, "boot"):
+		path = onbootPath
+	case strings.Contains(command, "shutdown"):
+		path = shutdownPath
+	}
+
+	// do nothing if the path does not exist
+	if _, err := os.Stat(path); err != nil && os.IsNotExist(err) {
+		os.Exit(0)
+	}
+
+	// get files; note ReadDir already sorts them
+	files, err := ioutil.ReadDir(path)
+	if err != nil {
+		log.Fatalf("Cannot read files in %s: %v", path, err)
+	}
+
+	status := 0
+
+	for _, file := range files {
+		name := file.Name()
+		fullPath := filepath.Join(path, name)
+		if err := prepare(fullPath); err != nil {
+			log.Printf("Error preparing %s: %v", name, err)
+			status = 1
+			continue
+		}
+		cmd := exec.Command(runcBinary, "run", "--bundle", fullPath, name)
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		if err := cmd.Run(); err != nil {
+			log.Printf("Error running %s: %v", name, err)
+			status = 1
+		}
+	}
+
+	os.Exit(status)
+}

pkg/runc/cmd/onboot/prepare.go

@@ -0,0 +1,21 @@
+package main
+
+// Please note this file is shared between pkg/runc and pkg/containerd
+// Update it in both places if you make changes
+
+import (
+	"path/filepath"
+	"syscall"
+)
+
+func prepare(path string) error {
+	rootfs := filepath.Join(path, "rootfs")
+	if err := syscall.Mount(rootfs, rootfs, "", syscall.MS_BIND, ""); err != nil {
+		return err
+	}
+	// remount rw
+	if err := syscall.Mount("", rootfs, "", syscall.MS_REMOUNT, ""); err != nil {
+		return err
+	}
+	return nil
+}

pkg/runc/etc/init.d/010-onboot

@@ -1,15 +0,0 @@
-#!/bin/sh
-
-# start onboot containers, run to completion
-
-if [ -d /containers/onboot ]
-then
-	for f in $(find /containers/onboot -mindepth 1 -maxdepth 1 | sort)
-	do
-		base="$(basename $f)"
-		/bin/mount --bind "$f/rootfs" "$f/rootfs"
-		mount -o remount,rw "$f/rootfs"
-		/usr/bin/runc run --bundle "$f" "$(basename $f)"
-		printf " - $base\n"
-	done
-fi

pkg/runc/etc/shutdown.d/010-onshutdown

@@ -1,15 +0,0 @@
-#!/bin/sh
-
-# start onshutdown containers, run to completion
-
-if [ -d /containers/onshutdown ]
-then
-	for f in $(find /containers/onshutdown -mindepth 1 -maxdepth 1 | sort)
-	do
-		base="$(basename $f)"
-		/bin/mount --bind "$f/rootfs" "$f/rootfs"
-		mount -o remount,rw "$f/rootfs"
-		/usr/bin/runc run --bundle "$f" "$(basename $f)"
-		printf " - $base\n"
-	done
-fi