generators: Add upstart-tty generator

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>

generators/generators.go

@@ -30,6 +30,8 @@ func Get(generator string) Generator {
 		return RemoveGenerator{}
 	case "dump":
 		return DumpGenerator{}
+	case "upstart-tty":
+		return UpstartTTYGenerator{}
 	}
 
 	return nil

generators/upstart_tty.go

@@ -0,0 +1,126 @@
+package generators
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	lxd "github.com/lxc/lxd/shared"
+	"github.com/lxc/lxd/shared/api"
+
+	"github.com/lxc/distrobuilder/image"
+	"github.com/lxc/distrobuilder/shared"
+)
+
+var upstartTTYJob = `start on starting tty1 or starting tty2 or starting tty3 or starting tty4 or starting tty5 or starting tty6
+instance $JOB
+
+script
+    set -eu
+
+    # Check that we're inside a container
+    [ -e "/run/container_type" ] || exit 0
+    [ "$(cat /run/container_type)" = "lxc" ] || exit 0
+
+    # Load PID1's environment
+    LXC_TTY=$(tr '\0' '\n' < /proc/1/environ | grep ^container_ttys= | cut -d= -f2-)
+
+    # Check if we have any consoles setup
+    if [ -z "${LXC_TTY}" ]; then
+        # No TTYs setup in this container
+        stop "${JOB}" >/dev/null 2>&1
+        exit 0
+    fi
+
+    TTY_COUNT=$(echo ${LXC_TTY} | wc -w)
+    JOB_ID="${JOB#tty}"
+
+    if [ "${JOB_ID}" -gt "${TTY_COUNT}" ]; then
+        # This console isn't available in the container
+        stop "${JOB}" >/dev/null 2>&1
+        exit 0
+    fi
+
+    # Allow the tty to start
+    exit 0
+end script
+`
+
+// UpstartTTYGenerator represents the UpstartTTY generator.
+type UpstartTTYGenerator struct{}
+
+// RunLXC creates a hostname template.
+func (g UpstartTTYGenerator) RunLXC(cacheDir, sourceDir string, img *image.LXCImage,
+	defFile shared.DefinitionFile) error {
+
+	// Skip if the file exists
+	if lxd.PathExists(filepath.Join(sourceDir, defFile.Path)) {
+		return nil
+	}
+
+	// Store original file
+	err := StoreFile(cacheDir, sourceDir, defFile.Path)
+	if err != nil {
+		return err
+	}
+
+	// Create new hostname file
+	file, err := os.Create(filepath.Join(sourceDir, defFile.Path))
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	// Write LXC specific string to the hostname file
+	_, err = file.WriteString(upstartTTYJob)
+	if err != nil {
+		return fmt.Errorf("Failed to write to upstart job file: %s", err)
+	}
+
+	// Add hostname path to LXC's templates file
+	return img.AddTemplate(defFile.Path)
+}
+
+// RunLXD creates a hostname template.
+func (g UpstartTTYGenerator) RunLXD(cacheDir, sourceDir string, img *image.LXDImage,
+	defFile shared.DefinitionFile) error {
+
+	// Skip if the file exists
+	if lxd.PathExists(filepath.Join(sourceDir, defFile.Path)) {
+		return nil
+	}
+
+	templateDir := filepath.Join(cacheDir, "templates")
+
+	err := os.MkdirAll(templateDir, 0755)
+	if err != nil {
+		return err
+	}
+
+	file, err := os.Create(filepath.Join(templateDir, "upstart-tty.tpl"))
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	_, err = file.WriteString(upstartTTYJob)
+	if err != nil {
+		return fmt.Errorf("Failed to write to upstart job file: %s", err)
+	}
+
+	// Add to LXD templates
+	img.Metadata.Templates[defFile.Path] = &api.ImageMetadataTemplate{
+		Template: "upstart-tty.tpl",
+		When: []string{
+			"create",
+		},
+	}
+
+	return err
+}
+
+// Run does nothing.
+func (g UpstartTTYGenerator) Run(cacheDir, sourceDir string,
+	defFile shared.DefinitionFile) error {
+	return nil
+}

shared/definition.go

@@ -159,10 +159,11 @@ func ValidateDefinition(def Definition) error {
 	}
 
 	validGenerators := []string{
+		"dump",
 		"hostname",
 		"hosts",
 		"remove",
-		"dump",
+		"upstart-tty",
 	}
 
 	for _, file := range def.Files {