package management: Allow dynamic loading of PM

Dynamic loading of package managers will allow other layers to simply
add their package manager code in package_manager/ and have bitbake find
it according to the package manager configuration. This is useful for
adding new (faster) package managers to Open Embedded while not increasing the
test scope or require Open Embedded to support more package managers.

How this is tested:
* Build core-image-minimal with all three package managers
* Build the sdk with all three package managers. dpkg fails, but
  it fails on master as well.
* Run the complete test suite, all tests passed except 16
* Run those 16 tests on master and verify that they fail there as well
* Fix errors making tests works on master but not with this patch.

Signed-off-by: Fredrik Gustafsson <fredrigu@axis.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 9 insertions, 27 deletions

diff --git a/meta/lib/oe/rootfs.py b/meta/lib/oe/rootfs.py
index 4e09eae6b9..4b747dd0f4 100644
--- a/meta/lib/oe/rootfs.py
+++ b/meta/lib/oe/rootfs.py
@@ -10,12 +10,6 @@ import shutil
 import os
 import subprocess
 import re
-from oe.package_manager.rpm.manifest import RpmManifest
-from oe.package_manager.ipk.manifest import OpkgManifest
-from oe.package_manager.deb.manifest import DpkgManifest
-from oe.package_manager.rpm import RpmPkgsList
-from oe.package_manager.ipk import OpkgPkgsList
-from oe.package_manager.deb import DpkgPkgsList
 
 class Rootfs(object, metaclass=ABCMeta):
     """
@@ -360,12 +354,9 @@ class Rootfs(object, metaclass=ABCMeta):
 
 
 def get_class_for_type(imgtype):
-    from oe.package_manager.rpm.rootfs import RpmRootfs
-    from oe.package_manager.ipk.rootfs import OpkgRootfs
-    from oe.package_manager.deb.rootfs import DpkgRootfs
-    return {"rpm": RpmRootfs,
-            "ipk": OpkgRootfs,
-            "deb": DpkgRootfs}[imgtype]
+    import importlib
+    mod = importlib.import_module('oe.package_manager.' + imgtype + '.rootfs')
+    return mod.PkgRootfs
 
 def variable_depends(d, manifest_dir=None):
     img_type = d.getVar('IMAGE_PKGTYPE')
@@ -375,17 +366,10 @@ def variable_depends(d, manifest_dir=None):
 def create_rootfs(d, manifest_dir=None, progress_reporter=None, logcatcher=None):
     env_bkp = os.environ.copy()
 
-    from oe.package_manager.rpm.rootfs import RpmRootfs
-    from oe.package_manager.ipk.rootfs import OpkgRootfs
-    from oe.package_manager.deb.rootfs import DpkgRootfs
     img_type = d.getVar('IMAGE_PKGTYPE')
-    if img_type == "rpm":
-        RpmRootfs(d, manifest_dir, progress_reporter, logcatcher).create()
-    elif img_type == "ipk":
-        OpkgRootfs(d, manifest_dir, progress_reporter, logcatcher).create()
-    elif img_type == "deb":
-        DpkgRootfs(d, manifest_dir, progress_reporter, logcatcher).create()
 
+    cls = get_class_for_type(img_type)
+    cls(d, manifest_dir, progress_reporter, logcatcher).create()
     os.environ.clear()
     os.environ.update(env_bkp)
 
@@ -395,12 +379,10 @@ def image_list_installed_packages(d, rootfs_dir=None):
         rootfs_dir = d.getVar('IMAGE_ROOTFS')
 
     img_type = d.getVar('IMAGE_PKGTYPE')
-    if img_type == "rpm":
-        return RpmPkgsList(d, rootfs_dir).list_pkgs()
-    elif img_type == "ipk":
-        return OpkgPkgsList(d, rootfs_dir, d.getVar("IPKGCONF_TARGET")).list_pkgs()
-    elif img_type == "deb":
-        return DpkgPkgsList(d, rootfs_dir).list_pkgs()
+
+    import importlib
+    cls = importlib.import_module('oe.package_manager.' + img_type)
+    return cls.PMPkgsList(d, rootfs_dir).list_pkgs()
 
 if __name__ == "__main__":
     """