Add some support to add files in Yaml config

You can specify a file with contents.

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

moby/config.go

@@ -1,6 +1,10 @@
 package main
 
 import (
+	"archive/tar"
+	"bytes"
+	"errors"
+	"path"
 	"strconv"
 	"strings"
 
@@ -8,12 +12,12 @@ import (
 )
 
 type Moby struct {
-	Kernel   string
+	Kernel string
-	Init     string
+	Init   string
-	System   []MobyImage
+	System []MobyImage
-	Database []struct {
+	Files  []struct {
-		File  string
+		Path     string
-		Value string
+		Contents string
 	}
 }
 
@@ -67,3 +71,54 @@ func ConfigToRun(image *MobyImage) []string {
 
 	return args
 }
+
+func Filesystem(m *Moby) (*bytes.Buffer, error) {
+	buf := new(bytes.Buffer)
+	tw := tar.NewWriter(buf)
+	defer tw.Close()
+
+	for _, f := range m.Files {
+		if f.Path == "" {
+			return buf, errors.New("Did not specify path for file")
+		}
+		if f.Contents == "" {
+			return buf, errors.New("Contents of file not specified")
+		}
+		// we need all the leading directories
+		parts := strings.Split(path.Dir(f.Path), "/")
+		root := ""
+		for _, p := range parts {
+			if p == "." || p == "/" {
+				continue
+			}
+			if root == "" {
+				root = p
+			} else {
+				root = root + "/" + p
+			}
+			hdr := &tar.Header{
+				Name:     root,
+				Typeflag: tar.TypeDir,
+				Mode:     0700,
+			}
+			err := tw.WriteHeader(hdr)
+			if err != nil {
+				return buf, err
+			}
+		}
+		hdr := &tar.Header{
+			Name: f.Path,
+			Mode: 0600,
+			Size: int64(len(f.Contents)),
+		}
+		err := tw.WriteHeader(hdr)
+		if err != nil {
+			return buf, err
+		}
+		_, err = tw.Write([]byte(f.Contents))
+		if err != nil {
+			return buf, err
+		}
+	}
+	return buf, nil
+}

moby/main.go

@@ -131,6 +131,13 @@ func build() {
 		containers = append(containers, buffer)
 	}
 
+	// add files
+	buffer, err = Filesystem(m)
+	if err != nil {
+		log.Fatalf("failed to add filesystem parts: %v", err)
+	}
+	containers = append(containers, buffer)
+
 	initrd, err := containersInitrd(containers)
 	if err != nil {
 		log.Fatalf("Failed to make initrd %v", err)

moby/moby.yaml

@@ -20,6 +20,6 @@ system:
      - CAP_SETUID
      - CAP_SETGID
     network_mode: host
-database:
+files:
-  - file: etc/docker/daemon.json
+  - path: etc/docker/daemon.json
-    value: '{"debug": true}'
+    contents: '{"debug": true}'