Current File : //lib/python3/dist-packages/cloudinit/templater.py
# Copyright (C) 2012 Canonical Ltd.
# Copyright (C) 2012 Hewlett-Packard Development Company, L.P.
# Copyright (C) 2012 Yahoo! Inc.
# Copyright (C) 2016 Amazon.com, Inc. or its affiliates.
#
# Author: Scott Moser <scott.moser@canonical.com>
# Author: Juerg Haefliger <juerg.haefliger@hp.com>
# Author: Joshua Harlow <harlowja@yahoo-inc.com>
# Author: Andrew Jorgensen <ajorgens@amazon.com>
#
# This file is part of cloud-init. See LICENSE file for license information.
# noqa: E402
import collections
import logging
import re
import sys
from typing import Any
from jinja2 import TemplateSyntaxError
from cloudinit import type_utils as tu
from cloudinit import util
from cloudinit.atomic_helper import write_file
# After bionic EOL, mypy==1.0.0 will be able to type-analyse dynamic
# base types, substitute this by:
# JUndefined: typing.Type
JUndefined: Any
try:
from jinja2 import DebugUndefined as _DebugUndefined
from jinja2 import Template as JTemplate
JINJA_AVAILABLE = True
JUndefined = _DebugUndefined
except (ImportError, AttributeError):
JINJA_AVAILABLE = False
JUndefined = object
LOG = logging.getLogger(__name__)
TYPE_MATCHER = re.compile(r"##\s*template:(.*)", re.I)
BASIC_MATCHER = re.compile(r"\$\{([A-Za-z0-9_.]+)\}|\$([A-Za-z0-9_.]+)")
MISSING_JINJA_PREFIX = "CI_MISSING_JINJA_VAR/"
class JinjaSyntaxParsingException(TemplateSyntaxError):
def __init__(
self,
error: TemplateSyntaxError,
) -> None:
super().__init__(
error.message or "unknown syntax error",
error.lineno,
error.name,
error.filename,
)
self.source = error.source
def __str__(self):
"""Avoid jinja2.TemplateSyntaxError multi-line __str__ format."""
return self.format_error_message(
syntax_error=self.message,
line_number=self.lineno,
line_content=self.source.splitlines()[self.lineno - 2].strip(),
)
@staticmethod
def format_error_message(
syntax_error: str,
line_number: str,
line_content: str = "",
) -> str:
"""Avoid jinja2.TemplateSyntaxError multi-line __str__ format."""
line_content = f": {line_content}" if line_content else ""
return JinjaSyntaxParsingException.message_template.format(
syntax_error=syntax_error,
line_number=line_number,
line_content=line_content,
)
message_template = (
"Unable to parse Jinja template due to syntax error: "
"{syntax_error} on line {line_number}{line_content}"
)
# Mypy, and the PEP 484 ecosystem in general, does not support creating
# classes with dynamic base types: https://stackoverflow.com/a/59636248
class UndefinedJinjaVariable(JUndefined):
"""Class used to represent any undefined jinja template variable."""
def __str__(self):
return "%s%s" % (MISSING_JINJA_PREFIX, self._undefined_name)
def __sub__(self, other):
other = str(other).replace(MISSING_JINJA_PREFIX, "")
raise TypeError(
'Undefined jinja variable: "{this}-{other}". Jinja tried'
' subtraction. Perhaps you meant "{this}_{other}"?'.format(
this=self._undefined_name, other=other
)
)
def basic_render(content, params):
"""This does simple replacement of bash variable like templates.
It identifies patterns like ${a} or $a and can also identify patterns like
${a.b} or $a.b which will look for a key 'b' in the dictionary rooted
by key 'a'.
"""
def replacer(match):
# Only 1 of the 2 groups will actually have a valid entry.
name = match.group(1)
if name is None:
name = match.group(2)
if name is None:
raise RuntimeError("Match encountered but no valid group present")
path = collections.deque(name.split("."))
selected_params = params
while len(path) > 1:
key = path.popleft()
if not isinstance(selected_params, dict):
raise TypeError(
"Can not traverse into"
" non-dictionary '%s' of type %s while"
" looking for subkey '%s'"
% (selected_params, tu.obj_name(selected_params), key)
)
selected_params = selected_params[key]
key = path.popleft()
if not isinstance(selected_params, dict):
raise TypeError(
"Can not extract key '%s' from non-dictionary '%s' of type %s"
% (key, selected_params, tu.obj_name(selected_params))
)
return str(selected_params[key])
return BASIC_MATCHER.sub(replacer, content)
def detect_template(text):
def jinja_render(content, params):
# keep_trailing_newline is in jinja2 2.7+, not 2.6
add = "\n" if content.endswith("\n") else ""
try:
return (
JTemplate(
content,
undefined=UndefinedJinjaVariable,
trim_blocks=True,
extensions=["jinja2.ext.do"],
).render(**params)
+ add
)
except TemplateSyntaxError as template_syntax_error:
template_syntax_error.lineno += 1
raise JinjaSyntaxParsingException(
error=template_syntax_error,
) from template_syntax_error
except Exception as unknown_error:
raise unknown_error from unknown_error
if text.find("\n") != -1:
ident, rest = text.split("\n", 1) # remove the first line
else:
ident = text
rest = ""
type_match = TYPE_MATCHER.match(ident)
if not type_match:
return ("basic", basic_render, text)
else:
template_type = type_match.group(1).lower().strip()
if template_type not in ("jinja", "basic"):
raise ValueError(
"Unknown template rendering type '%s' requested"
% template_type
)
if template_type == "jinja" and not JINJA_AVAILABLE:
LOG.warning(
"Jinja not available as the selected renderer for"
" desired template, reverting to the basic renderer."
)
return ("basic", basic_render, rest)
elif template_type == "jinja" and JINJA_AVAILABLE:
return ("jinja", jinja_render, rest)
# Only thing left over is the basic renderer (it is always available).
return ("basic", basic_render, rest)
def render_from_file(fn, params):
if not params:
params = {}
template_type, renderer, content = detect_template(util.load_text_file(fn))
LOG.debug("Rendering content of '%s' using renderer %s", fn, template_type)
return renderer(content, params)
def render_to_file(fn, outfn, params, mode=0o644):
contents = render_from_file(fn, params)
util.write_file(outfn, contents, mode=mode)
def render_string(content, params):
"""Render string"""
if not params:
params = {}
_template_type, renderer, content = detect_template(content)
return renderer(content, params)
def render_template(variant, template, output, is_yaml, prefix=None):
with open(template, "r") as fh:
contents = fh.read()
tpl_params = {"variant": variant, "prefix": prefix}
contents = (render_string(contents, tpl_params)).rstrip() + "\n"
if is_yaml:
out = util.load_yaml(contents, default=True)
if not out:
raise RuntimeError(
"Cannot render template file %s - invalid yaml." % template
)
if output == "-":
sys.stdout.write(contents)
else:
write_file(output, contents, omode="w")
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