Identify and create source image

Signed-off-by: Luiz Carvalho <lucarval@redhat.com>

.gitignore

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+/sources

build-source-image

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+#!/bin/env python3
+from concurrent.futures import ThreadPoolExecutor
+from contextlib import contextmanager
+import os
+import os.path
+import shutil
+import subprocess
+
+
+def handle_identify_command(image, dest_path):
+    with _buildah_build(image) as (container, mount_path):
+        print(f'Using {container} at path {mount_path}...')
+        release = _run_command(
+            ('rpm', '-q', '--queryformat', '%{VERSION}\n', '--root', mount_path, '-f',
+             '/etc/os-release')).strip()
+        src_rpms = _run_command(
+            ('rpm', '-qa', '--root', mount_path, '--queryformat', '%{SOURCERPM}\n')).splitlines()
+        src_rpms = sorted({src_rpm for src_rpm in src_rpms if src_rpm and '(none)' not in src_rpm})
+        os.makedirs(dest_path, exist_ok=True)
+        with ThreadPoolExecutor(max_workers=20) as executor:
+            {
+                executor.submit(_download_srpm, src_rpm, release, dest_path): src_rpm
+                for src_rpm in src_rpms
+            }
+
+
+def _download_srpm(src_rpm, release, dest_path):
+    if os.path.exists(os.path.join(dest_path, src_rpm)):
+        return
+    rpm_name = src_rpm.replace('.src.rpm', '')
+    print(f'Fetching source for {rpm_name}...')
+    try:
+        _run_command(('dnf', 'download', '--release', release, '--source', rpm_name),
+                     {'cwd': dest_path})
+    except RuntimeError:
+        print(f'ERROR: Cannot download source for {rpm_name}')
+
+
+def handle_create_command(dest_path, dest_image):
+    with _buildah_build('scratch') as (container, mount_path):
+        print(f'Using {container} at path {mount_path}...')
+        for source_archive in sorted(os.listdir(dest_path)):
+            source_archive_path = os.path.join(dest_path, source_archive)
+            if not os.path.isfile(source_archive_path):
+                continue
+            print(f'Processing {source_archive} source archive...')
+            if source_archive.endswith('.src.rpm'):
+                copy_path = os.path.join(mount_path, 'RPMS')
+            else:
+                copy_path = os.path.join(mount_path, 'others')
+            os.makedirs(copy_path, exist_ok=True)
+            shutil.copy(source_archive_path, copy_path)
+            _run_command(('buildah', 'commit', container, source_archive))
+
+        _run_command(('buildah', 'commit', container, dest_image))
+
+
+@contextmanager
+def _buildah_build(image):
+    container = _run_command(('buildah', 'from', image)).strip()
+    mount_path = _run_command(('buildah', 'mount', container)).strip()
+    yield container, mount_path
+    _run_command(('buildah', 'umount', container))
+    _run_command(('buildah', 'rm', container))
+
+
+def _run_command(command, params=None):
+    if params is None:
+        params = {}
+    params.setdefault('capture_output', True)
+    params.setdefault('universal_newlines', True)
+    params.setdefault('encoding', 'utf-8')
+
+    response = subprocess.run(command, **params)
+    returncode = response.returncode
+    if returncode != 0:
+        raise RuntimeError(f'Command "{command}" failed with return code {returncode}')
+    return response.stdout
+
+
+if __name__ == '__main__':
+    from argparse import ArgumentParser
+    parser = ArgumentParser(
+        description='Tool to build a source image based on an existing OCI image')
+    subparsers = parser.add_subparsers(dest='command')
+
+    identifier_parser = subparsers.add_parser(
+        'identify', help='Identify and download the source code for an existing OCI image')
+    identifier_parser.add_argument('image', help='Reference to an existing OCI image')
+    identifier_parser.add_argument(
+        '--dest-path', default='sources',
+        help='Local path to download sources, defaults to "sources"')
+
+    create_parser = subparsers.add_parser(
+        'create', help='Create a source image with the provide sources')
+    create_parser.add_argument(
+        'dest_image', help='Target reference to be used for the source image')
+    create_parser.add_argument(
+        '--dest-path', default='sources',
+        help='Local path containing sources, defaults to "sources"')
+
+    args = parser.parse_args()
+    if args.command == 'identify':
+        handle_identify_command(args.image, args.dest_path)
+    elif args.command == 'create':
+        handle_create_command(args.dest_path, args.dest_image)
+    else:
+        raise ValueError('Please specify a valid subcommand')