Introduce BuildType for normal, force, scratch and metadata builds

build/usr/bin/lxcbuild

@@ -5,7 +5,7 @@ import argparse
 import os
 import sys
 from lxcbuild.app import App
-from lxcbuild.image import Image
+from lxcbuild.image import BuildType, Image
 
 parser = argparse.ArgumentParser(description='VM application builder and packager')
 group = parser.add_mutually_exclusive_group()
@@ -22,8 +22,10 @@ args = parser.parse_args()
 
 def build_and_pack_image(path, args):
     image = Image()
-    image.force_build = args.force or args.scratch
+    if args.scratch:
-    image.scratch_build = args.scratch
+        image.build_type = BuildType.SCRATCH
+    elif args.force:
+        image.build_type = BuildType.FORCE
     image.build_and_pack(path)
 
 def pack_app(path):

build/usr/lib/python3.6/lxcbuild/image.py

@@ -3,43 +3,55 @@
 import os
 import sys
 
+from enum import Enum
 from lxcmgr import lxcmgr
 
 from .imagebuilder import ImageBuilder, ImageExistsError, ImageNotFoundError
 from .imagepacker import ImagePacker
 from .packer import PackageExistsError
 
+class BuildType(Enum):
+    NORMAL = 1
+    FORCE = 2
+    SCRATCH = 3
+    METADATA = 4
+
 class Image:
     def __init__(self):
         self.name = None
         self.conf = {}
         self.lxcfile = None
         self.build_dir = None
-        self.force_build = False
+        self.build_type = BuildType.NORMAL
-        self.scratch_build = False
+        self.pack = False
 
     def build_and_pack(self, lxcfile):
         self.lxcfile = lxcfile
         self.build_dir = os.path.dirname(lxcfile)
         self.conf['build'] = True
-        try:
         builder = ImageBuilder(self)
+        try:
             builder.build()
             # Packaging needs to happen in any case after a successful build in order to prevent outdated packages
-            self.force_build = True
+            self.pack = True
         except ImageExistsError as e:
+            # If container already exists and build hasn't been forced, rerun the build just for metadata which are still needed for packaging
             print('Image {} already exists, skipping build tasks'.format(e))
+            self.build_type = BuildType.METADATA
+            builder.build()
         except ImageNotFoundError as e:
+            # If one of the layers is missing, cleanup and die
             print('Image {} not found, can\'t build {}'.format(e, self.name))
             builder.clean()
             sys.exit(1)
         except:
-            if not self.scratch_build:
+            # If build fails with another exception, cleanup (unless we were doing scratch build) and re-raise
+            if not self.build_type == BuildType.SCRATCH:
                 builder.clean()
             raise
         del self.conf['build']
         # If we're doing a scratch build, regenerate the final LXC container configuration including ephemeral layer
-        if self.scratch_build:
+        if self.build_type == BuildType.SCRATCH:
             lxcmgr.create_container(self.name, self.conf)
         else:
             try:

build/usr/lib/python3.6/lxcbuild/imagebuilder.py

@@ -9,6 +9,8 @@ from lxcmgr import lxcmgr
 from lxcmgr.paths import LXC_STORAGE_DIR
 from lxcmgr.pkgmgr import PkgMgr
 
+from .image import BuildType
+
 class ImageExistsError(Exception):
     pass
 
@@ -65,6 +67,9 @@ class ImageBuilder:
 
     def run_script(self, script):
         # Creates a temporary container, runs a script in its namespace, and stores the modifications as part of the image
+        if self.image.build_type == BuildType.METADATA:
+            # Don't run anything if we're building just metadata
+            return
         lxcmgr.create_container(self.image.name, self.image.conf)
         sh = os.path.join(LXC_STORAGE_DIR, self.image.name, 'run.sh')
         with open(sh, 'w') as f:
@@ -73,7 +78,8 @@ class ImageBuilder:
         os.chown(sh, 100000, 100000)
         subprocess.run(['lxc-execute', self.image.name, '--', '/bin/sh', '-lc', '/run.sh'], check=True)
         os.unlink(sh)
-        if not self.image.scratch_build:
+        if not self.image.build_type == BuildType.SCRATCH:
+            # Don't delete the temporary container if we're doing scratch build
             lxcmgr.destroy_container(self.image.name)
 
     def set_name(self, name):
@@ -82,7 +88,7 @@ class ImageBuilder:
         self.image.conf['layers'] = [name]
         image_path = self.get_layer_path(name)
         if os.path.exists(image_path):
-            if self.image.force_build:
+            if self.image.build_type in (BuildType.FORCE, BuildType.SCRATCH):
                 self.clean()
             else:
                 raise ImageExistsError(image_path)
@@ -93,10 +99,13 @@ class ImageBuilder:
         # Extend list of layers with the list of layers from parent image
         # Raies an exception when IMAGE has no name
         pkgmgr = PkgMgr()
-        self.image.conf['layers'].extend(pkgmgr.installed_packages[image]['layers'])
+        self.image.conf['layers'].extend(pkgmgr.installed_packages['images'][image]['layers'])
 
     def copy_files(self, src, dst):
         # Copy files from the host or download them from a http(s) URL
+        if self.image.build_type == BuildType.METADATA:
+            # Don't copy anything if we're building just metadata
+            return
         dst = os.path.join(LXC_STORAGE_DIR, self.image.name, dst)
         if src.startswith('http://') or src.startswith('https://'):
             unpack_http_archive(src, dst)

build/usr/lib/python3.6/lxcbuild/imagepacker.py

@@ -19,7 +19,7 @@ class ImagePacker(Packer):
         self.xz_path = '{}.xz'.format(self.tar_path)
 
     def pack(self):
-        if self.image.force_build:
+        if self.image.pack:
             self.unregister()
             try:
                 os.unlink(self.xz_path)