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: / lib / python3 / dist-packages / cloudinit / handlers /
Filename : jinja_template.py
back
# This file is part of cloud-init. See LICENSE file for license information.

import copy
import os
import re
from errno import EACCES
from typing import Optional, Type

from cloudinit import handlers
from cloudinit import log as logging
from cloudinit.helpers import Paths
from cloudinit.settings import PER_ALWAYS
from cloudinit.templater import (
    MISSING_JINJA_PREFIX,
    detect_template,
    render_string,
)
from cloudinit.util import b64d, json_dumps, load_file, load_json

JUndefinedError: Type[Exception]
try:
    from jinja2.exceptions import UndefinedError as JUndefinedError
    from jinja2.lexer import operator_re
except ImportError:
    # No jinja2 dependency
    JUndefinedError = Exception
    operator_re = re.compile(r"[-.]")

LOG = logging.getLogger(__name__)


class JinjaLoadError(Exception):
    pass


class NotJinjaError(Exception):
    pass


class JinjaTemplatePartHandler(handlers.Handler):

    prefixes = ["## template: jinja"]

    def __init__(self, paths: Paths, **_kwargs):
        handlers.Handler.__init__(self, PER_ALWAYS, version=3)
        self.paths = paths
        self.sub_handlers = {}
        for handler in _kwargs.get("sub_handlers", []):
            for ctype in handler.list_types():
                self.sub_handlers[ctype] = handler

    def handle_part(self, data, ctype, filename, payload, frequency, headers):
        if ctype in handlers.CONTENT_SIGNALS:
            return
        jinja_json_file = self.paths.get_runpath("instance_data_sensitive")
        rendered_payload = render_jinja_payload_from_file(
            payload, filename, jinja_json_file
        )
        if not rendered_payload:
            return
        subtype = handlers.type_from_starts_with(rendered_payload)
        sub_handler = self.sub_handlers.get(subtype)
        if not sub_handler:
            LOG.warning(
                "Ignoring jinja template for %s. Could not find supported"
                " sub-handler for type %s",
                filename,
                subtype,
            )
            return
        if sub_handler.handler_version == 3:
            sub_handler.handle_part(
                data, ctype, filename, rendered_payload, frequency, headers
            )
        elif sub_handler.handler_version == 2:
            sub_handler.handle_part(
                data, ctype, filename, rendered_payload, frequency
            )


def render_jinja_payload_from_file(
    payload, payload_fn, instance_data_file, debug=False
):
    """Render a jinja template payload sourcing variables from jinja_vars_path.

    @param payload: String of jinja template content. Should begin with
        ## template: jinja\n.
    @param payload_fn: String representing the filename from which the payload
        was read used in error reporting. Generally in part-handling this is
        'part-##'.
    @param instance_data_file: A path to a json file containing variables that
        will be used as jinja template variables.

    @return: A string of jinja-rendered content with the jinja header removed.
        Returns None on error.
    """
    if detect_template(payload)[0] != "jinja":
        raise NotJinjaError("Payload is not a jinja template")
    instance_data = {}
    rendered_payload = None
    if not os.path.exists(instance_data_file):
        raise JinjaLoadError(
            "Cannot render jinja template vars. Instance data not yet"
            " present at %s" % instance_data_file
        )
    try:
        instance_data = load_json(load_file(instance_data_file))
    except Exception as e:
        msg = "Loading Jinja instance data failed"
        if isinstance(e, (IOError, OSError)):
            if e.errno == EACCES:
                msg = (
                    "Cannot render jinja template vars. No read permission on"
                    " '%s'. Try sudo" % instance_data_file
                )
        raise JinjaLoadError(msg) from e

    rendered_payload = render_jinja_payload(
        payload, payload_fn, instance_data, debug
    )
    if not rendered_payload:
        return None
    return rendered_payload


def render_jinja_payload(payload, payload_fn, instance_data, debug=False):
    instance_jinja_vars = convert_jinja_instance_data(
        instance_data,
        decode_paths=instance_data.get("base64-encoded-keys", []),
        include_key_aliases=True,
    )
    if debug:
        LOG.debug(
            "Converted jinja variables\n%s", json_dumps(instance_jinja_vars)
        )
    try:
        rendered_payload = render_string(payload, instance_jinja_vars)
    except (TypeError, JUndefinedError) as e:
        LOG.warning("Ignoring jinja template for %s: %s", payload_fn, str(e))
        return None
    warnings = [
        "'%s'" % var.replace(MISSING_JINJA_PREFIX, "")
        for var in re.findall(
            r"%s[^\s]+" % MISSING_JINJA_PREFIX, rendered_payload
        )
    ]
    if warnings:
        LOG.warning(
            "Could not render jinja template variables in file '%s': %s",
            payload_fn,
            ", ".join(warnings),
        )
    return rendered_payload


def get_jinja_variable_alias(orig_name: str) -> Optional[str]:
    """Return a jinja variable alias, replacing any operators with underscores.

    Provide underscore-delimited key aliases to simplify dot-notation
    attribute references for keys which contain operators "." or "-".
    This provides for simpler short-hand jinja attribute notation
    allowing one to avoid quoting keys which contain operators.
    {{ ds.v1_0.config.user_network_config }} instead of
    {{ ds['v1.0'].config["user.network-config"] }}.

    :param orig_name: String representing a jinja variable name to scrub/alias.

    :return: A string with any jinja operators replaced if needed. Otherwise,
        none if no alias required.
    """
    alias_name = re.sub(operator_re, "_", orig_name)
    if alias_name != orig_name:
        return alias_name
    return None


def convert_jinja_instance_data(
    data, prefix="", sep="/", decode_paths=(), include_key_aliases=False
):
    """Process instance-data.json dict for use in jinja templates.

    Replace hyphens with underscores for jinja templates and decode any
    base64_encoded_keys.
    """
    result = {}
    decode_paths = [path.replace("-", "_") for path in decode_paths]
    for key, value in sorted(data.items()):
        key_path = "{0}{1}{2}".format(prefix, sep, key) if prefix else key
        if key_path in decode_paths:
            value = b64d(value)
        if isinstance(value, dict):
            result[key] = convert_jinja_instance_data(
                value,
                key_path,
                sep=sep,
                decode_paths=decode_paths,
                include_key_aliases=include_key_aliases,
            )
            if re.match(r"v\d+$", key):
                # Copy values to top-level aliases
                for subkey, subvalue in result[key].items():
                    result[subkey] = copy.deepcopy(subvalue)
        else:
            result[key] = value
        if include_key_aliases:
            alias_name = get_jinja_variable_alias(key)
            if alias_name:
                result[alias_name] = copy.deepcopy(result[key])
    return result