Change -i option to use OCIImage

This is work towards #948

This commit makes changes to hook up the CLI option for container
image to use the OCIImage class rather than the DockerImage class.
The argument for the -i option is now --image.

- If the raw_image option is given, we assume that this is the
  output of "docker save" rather than some other tool.
- In the load_full_image function, we provide an "image_type"
  string which should either be "oci" or "docker", "oci" being the
  default. Based on this string, we either return an instance of
  OCIImage or DockerImage.
- For the Dockerfile or Lock features, we explicitly create
  DockerImage objects.

Signed-off-by: Nisha K <nishak@vmware.com>

tern/__main__.py

@@ -70,8 +70,8 @@ def check_image_input(options):
             logger.critical(errors.incorrect_raw_option)
             sys.exit(1)
     # Check if the image string has the right format
-    if options.docker_image:
-        if not check_image_string(options.docker_image):
+    if options.image:
+        if not check_image_string(options.image):
             logger.critical(errors.incorrect_image_string_format)
             sys.exit(1)
 
@@ -108,9 +108,9 @@ def do_main(args):
                 drun.execute_dockerfile(args)
             else:
                 logger.critical("Currently --layer/-y can only be used with"
-                                " --docker-image/-i")
+                                " --image/-i")
                 sys.exit(1)
-        elif args.docker_image or args.raw_image:
+        elif args.image or args.raw_image:
             check_image_input(args)
             # If the checks are OK, execute for docker image
             crun.execute_image(args)
@@ -167,15 +167,13 @@ def main():
     parser_report.add_argument('-d', '--dockerfile', type=check_file_existence,
                                help="Dockerfile used to build the Docker"
                                " image")
-    parser_report.add_argument('-i', '--docker-image',
-                               help="Docker image that exists locally -"
-                               " image:tag"
-                               " The option can be used to pull docker"
-                               " images by digest as well -"
-                               " <repo>@<digest-type>:<digest>")
+    parser_report.add_argument('-i', '--image',
+                               help="A container image referred either by "
+                               " repo:tag or repo@digest-type:digest")
     parser_report.add_argument('-w', '--raw-image', metavar='FILE',
                                help="Raw container image that exists locally "
-                               "in the form of a tar archive.")
+                               "in the form of a tar archive. Only the output"
+                               "of 'docker save' is supported")
     parser_report.add_argument('-y', '--layer', metavar='LAYER_NUMBER',
                                const=1, action='store',
                                dest='load_until_layer',

tern/analyze/default/container/image.py

@@ -13,6 +13,7 @@
 
 from tern.classes.notice import Notice
 from tern.classes.docker_image import DockerImage
+from tern.classes.oci_image import OCIImage
 from tern.utils import constants
 from tern.analyze import passthrough
 from tern.analyze.default.container import single_layer
@@ -23,24 +24,29 @@
 logger = logging.getLogger(constants.logger_name)
 
 
-def load_full_image(image_tag_string, load_until_layer=0):
-    '''Create image object from image name and tag and return the object.
-    Loads only as many layers as needed.'''
-    test_image = DockerImage(image_tag_string)
+def load_full_image(image_tag_string, image_type='oci', load_until_layer=0):
+    """Create image object from image name and tag and return the object.
+    The kind of image object is created based on the image_type.
+    image_type = oci OR docker
+    Loads only as many layers as needed."""
+    if image_type == 'oci':
+        image = OCIImage(image_tag_string)
+    elif image_type == 'docker':
+        image = DockerImage(image_tag_string)
     failure_origin = formats.image_load_failure.format(
-        testimage=test_image.repotag)
+        testimage=image.repotag)
     try:
-        test_image.load_image(load_until_layer)
+        image.load_image(load_until_layer)
     except (NameError,
             subprocess.CalledProcessError,
             IOError,
             docker.errors.APIError,
             ValueError,
             EOFError) as error:
         logger.warning('Error in loading image: %s', str(error))
-        test_image.origins.add_notice_to_origins(
+        image.origins.add_notice_to_origins(
             failure_origin, Notice(str(error), 'error'))
-    return test_image
+    return image
 
 
 def default_analyze(image_obj, options):

tern/analyze/default/container/run.py

@@ -14,7 +14,7 @@
 from tern.report import report
 from tern.report import formats
 from tern import prep
-from tern.load import docker_api
+from tern.load import skopeo
 from tern.analyze import common
 from tern.analyze.default.container import image as cimage
 
@@ -27,28 +27,20 @@ def extract_image(args):
     """The image can either be downloaded from a container registry or provided
     as an image tarball. Extract the image into a working directory accordingly
     Return an image name and tag and an image digest if it exists"""
-    if args.docker_image:
-        # extract the docker image
-        image_attrs = docker_api.dump_docker_image(args.docker_image)
-        if image_attrs:
-            # repo name and digest is preferred, but if that doesn't exist
-            # the repo name and tag will do. If neither exist use repo Id.
-            if image_attrs['Id']:
-                image_string = image_attrs['Id']
-            if image_attrs['RepoTags']:
-                image_string = image_attrs['RepoTags'][0]
-            if image_attrs['RepoDigests']:
-                image_string = image_attrs['RepoDigests'][0]
-            return image_string
-        logger.critical("Cannot extract Docker image")
+    if args.image:
+        # download the image
+        result = skopeo.pull_image(args.image)
+        if result:
+            return 'oci', args.image
+        logger.critical("Cannot download Container image: \"%s\"", args.image)
     if args.raw_image:
         # for now we assume that the raw image tarball is always
         # the product of "docker save", hence it will be in
         # the docker style layout
         if rootfs.extract_tarfile(args.raw_image, rootfs.get_working_dir()):
-            return args.raw_image
-        logger.critical("Cannot extract raw image")
-    return None
+            return 'docker', args.raw_image
+        logger.critical("Cannot extract raw Docker image")
+    return None, None
 
 
 def setup(image_obj):
@@ -72,11 +64,11 @@ def teardown(image_obj):
 def execute_image(args):
     """Execution path for container images"""
     logger.debug('Starting analysis...')
-    image_string = extract_image(args)
+    image_type, image_string = extract_image(args)
     # If the image has been extracted, load the metadata
-    if image_string:
+    if image_type and image_string:
         full_image = cimage.load_full_image(
-            image_string, args.load_until_layer)
+            image_string, image_type, args.load_until_layer)
         # check if the image was loaded successfully
         if full_image.origins.is_empty():
             # Add an image origin here

tern/analyze/default/debug/run.py

@@ -26,10 +26,10 @@
 from tern.analyze.default.container import multi_layer
 
 
-def check_image_obj(image_string):
+def check_image_obj(image_string, image_type):
     """Return the image object and if it was loaded successfully"""
     if image_string:
-        full_image = cimage.load_full_image(image_string)
+        full_image = cimage.load_full_image(image_string, image_type)
         if full_image.origins.is_empty():
             return full_image, True
         print("Something went wrong in loading the image")
@@ -190,9 +190,9 @@ def recover():
 
 def execute_debug(args):
     """Debug container images"""
-    if args.docker_image:
-        image_string = run.extract_image(args)
-        full_image, success = check_image_obj(image_string)
+    if args.image:
+        image_type, image_string = run.extract_image(args)
+        full_image, success = check_image_obj(image_string, image_type)
         if success:
             if args.keys:
                 # we have an image to mount and some scripts to invoke

tern/analyze/default/dockerfile/run.py

@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 #
-# Copyright (c) 2019-2020 VMware, Inc. All Rights Reserved.
+# Copyright (c) 2019-2021 VMware, Inc. All Rights Reserved.
 # SPDX-License-Identifier: BSD-2-Clause
 
 """
@@ -123,7 +123,7 @@ def full_image_analysis(dfile, options):
     """This subroutine is executed when a Dockerfile is successfully built"""
     image_list = []
     # attempt to load the built image metadata
-    full_image = cimage.load_full_image(dfile)
+    full_image = cimage.load_full_image(dfile, image_type='docker')
     if full_image.origins.is_empty():
         # Add an image origin here
         full_image.origins.add_notice_origin(