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dockerfileparse.py
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109 lines (83 loc) · 3.06 KB
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import re
LINE_CONTINUATION_REGEX = re.compile(r"(\s)*\\(\s)*\n")
COMMAND_REGEX = re.compile("([A-Za-z]+)\s(.*)")
COMMENT_CHARACTER = "#"
LATEST_TAG = "latest"
class ParsedDockerfile(object):
def __init__(self, commands):
self.commands = commands
def _get_commands_of_kind(self, kind):
return [command for command in self.commands if command["command"] == kind]
def _get_from_image_identifier(self):
from_commands = self._get_commands_of_kind("FROM")
if not from_commands:
return None
return from_commands[-1]["parameters"]
@staticmethod
def parse_image_identifier(image_identifier):
"""
Parses a docker image identifier, and returns a tuple of image name and tag, where the tag
is filled in with "latest" if left unspecified.
"""
# Note:
# Dockerfile images references can be of multiple forms:
# server:port/some/path
# somepath
# server/some/path
# server/some/path:tag
# server:port/some/path:tag
parts = image_identifier.strip().split(":")
if len(parts) == 1:
# somepath
return (parts[0], LATEST_TAG)
# Otherwise, determine if the last part is a port
# or a tag.
if parts[-1].find("/") >= 0:
# Last part is part of the hostname.
return (image_identifier, LATEST_TAG)
# Remaining cases:
# server/some/path:tag
# server:port/some/path:tag
return (":".join(parts[0:-1]), parts[-1])
def get_base_image(self):
"""
Return the base image without the tag name.
"""
return self.get_image_and_tag()[0]
def get_image_and_tag(self):
"""
Returns the image and tag from the FROM line of the dockerfile.
"""
image_identifier = self._get_from_image_identifier()
if image_identifier is None:
return (None, None)
return self.parse_image_identifier(image_identifier)
def strip_comments(contents):
lines = []
for line in contents.split("\n"):
index = line.find(COMMENT_CHARACTER)
if index < 0:
lines.append(line)
continue
line = line[:index]
lines.append(line)
return "\n".join(lines)
def join_continued_lines(contents):
return LINE_CONTINUATION_REGEX.sub("", contents)
def parse_dockerfile(contents):
# If we receive ASCII, translate into unicode.
try:
contents = contents.decode("utf-8")
except ValueError:
# Already unicode or unable to convert.
pass
contents = join_continued_lines(strip_comments(contents))
lines = [line.strip() for line in contents.split("\n") if len(line) > 0]
commands = []
for line in lines:
match_command = COMMAND_REGEX.match(line)
if match_command:
command = match_command.group(1).upper()
parameters = match_command.group(2)
commands.append({"command": command, "parameters": parameters})
return ParsedDockerfile(commands)