95 lines
2.7 KiB
Python
95 lines
2.7 KiB
Python
import re
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LINE_CONTINUATION_REGEX = re.compile(r'(\s)*\\(\s)*\n')
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COMMAND_REGEX = re.compile('([A-Za-z]+)\s(.*)')
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COMMENT_CHARACTER = '#'
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LATEST_TAG = 'latest'
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class ParsedDockerfile(object):
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def __init__(self, commands):
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self.commands = commands
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def _get_commands_of_kind(self, kind):
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return [command for command in self.commands if command['command'] == kind]
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def _get_from_image_identifier(self):
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from_commands = self._get_commands_of_kind('FROM')
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if not from_commands:
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return None
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return from_commands[-1]['parameters']
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@staticmethod
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def parse_image_identifier(image_identifier):
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""" Parses a docker image identifier, and returns a tuple of image name and tag, where the tag
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is filled in with "latest" if left unspecified.
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"""
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# Note:
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# Dockerfile images references can be of multiple forms:
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# server:port/some/path
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# somepath
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# server/some/path
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# server/some/path:tag
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# server:port/some/path:tag
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parts = image_identifier.strip().split(':')
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if len(parts) == 1:
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# somepath
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return (parts[0], LATEST_TAG)
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# Otherwise, determine if the last part is a port
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# or a tag.
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if parts[-1].find('/') >= 0:
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# Last part is part of the hostname.
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return (image_identifier, LATEST_TAG)
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# Remaining cases:
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# server/some/path:tag
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# server:port/some/path:tag
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return (':'.join(parts[0:-1]), parts[-1])
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def get_base_image(self):
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""" Return the base image without the tag name. """
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return self.get_image_and_tag()[0]
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def get_image_and_tag(self):
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""" Returns the image and tag from the FROM line of the dockerfile. """
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image_identifier = self._get_from_image_identifier()
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if image_identifier is None:
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return (None, None)
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return self.parse_image_identifier(image_identifier)
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def strip_comments(contents):
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lines = [line for line in contents.split('\n') if not line.startswith(COMMENT_CHARACTER)]
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return '\n'.join(lines)
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def join_continued_lines(contents):
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return LINE_CONTINUATION_REGEX.sub('', contents)
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def parse_dockerfile(contents):
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contents = join_continued_lines(strip_comments(contents))
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lines = [line for line in contents.split('\n') if len(line) > 0]
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commands = []
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for line in lines:
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match_command = COMMAND_REGEX.match(line)
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if match_command:
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command = match_command.group(1).upper()
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parameters = match_command.group(2)
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commands.append({
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'command': command,
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'parameters': parameters
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})
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return ParsedDockerfile(commands)
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def serialize_dockerfile(parsed_dockerfile):
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return '\n'.join([' '.join([command['command'], command['parameters']])
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for command in parsed_dockerfile.commands])
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