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Filename : helpers.py
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# Copyright (C) 2012 Canonical Ltd.
# Copyright (C) 2012, 2013 Hewlett-Packard Development Company, L.P.
# Copyright (C) 2012 Yahoo! Inc.
#
# Author: Scott Moser <scott.moser@canonical.com>
# Author: Juerg Haefliger <juerg.haefliger@hp.com>
# Author: Joshua Harlow <harlowja@yahoo-inc.com>
#
# This file is part of cloud-init. See LICENSE file for license information.

import contextlib
import logging
import os
from configparser import NoOptionError, NoSectionError, RawConfigParser
from io import StringIO
from time import time

from cloudinit import persistence, settings, type_utils, util
from cloudinit.settings import CFG_ENV_NAME, PER_ALWAYS, PER_INSTANCE, PER_ONCE

LOG = logging.getLogger(__name__)


class LockFailure(Exception):
    pass


class DummyLock:
    pass


class DummySemaphores:
    def __init__(self):
        pass

    @contextlib.contextmanager
    def lock(self, _name, _freq, _clear_on_fail=False):
        yield DummyLock()

    def has_run(self, _name, _freq):
        return False

    def clear(self, _name, _freq):
        return True


class FileLock:
    def __init__(self, fn):
        self.fn = fn

    def __str__(self):
        return "<%s using file %r>" % (type_utils.obj_name(self), self.fn)


def canon_sem_name(name):
    return name.replace("-", "_")


class FileSemaphores:
    def __init__(self, sem_path):
        self.sem_path = sem_path

    @contextlib.contextmanager
    def lock(self, name, freq, clear_on_fail=False):
        name = canon_sem_name(name)
        try:
            yield self._acquire(name, freq)
        except Exception:
            if clear_on_fail:
                self.clear(name, freq)
            raise

    def clear(self, name, freq):
        name = canon_sem_name(name)
        sem_file = self._get_path(name, freq)
        try:
            util.del_file(sem_file)
        except (IOError, OSError):
            util.logexc(LOG, "Failed deleting semaphore %s", sem_file)
            return False
        return True

    def _acquire(self, name, freq):
        # Check again if its been already gotten
        if self.has_run(name, freq):
            return None
        # This is a race condition since nothing atomic is happening
        # here, but this should be ok due to the nature of when
        # and where cloud-init runs... (file writing is not a lock...)
        sem_file = self._get_path(name, freq)
        contents = "%s: %s\n" % (os.getpid(), time())
        try:
            util.write_file(sem_file, contents)
        except (IOError, OSError):
            util.logexc(LOG, "Failed writing semaphore file %s", sem_file)
            return None
        return FileLock(sem_file)

    def has_run(self, name, freq):
        if not freq or freq == PER_ALWAYS:
            return False

        cname = canon_sem_name(name)
        sem_file = self._get_path(cname, freq)
        # This isn't really a good atomic check
        # but it suffices for where and when cloudinit runs
        return os.path.exists(sem_file)

    def _get_path(self, name, freq):
        sem_path = self.sem_path
        if not freq or freq == PER_INSTANCE:
            return os.path.join(sem_path, name)
        else:
            return os.path.join(sem_path, "%s.%s" % (name, freq))


class Runners:
    def __init__(self, paths):
        self.paths = paths
        self.sems = {}

    def _get_sem(self, freq):
        if freq == PER_ALWAYS or not freq:
            return None
        sem_path = None
        if freq == PER_INSTANCE:
            # This may not exist,
            # so thats why we still check for none
            # below if say the paths object
            # doesn't have a datasource that can
            # provide this instance path...
            sem_path = self.paths.get_ipath("sem")
        elif freq == PER_ONCE:
            sem_path = self.paths.get_cpath("sem")
        if not sem_path:
            return None
        if sem_path not in self.sems:
            self.sems[sem_path] = FileSemaphores(sem_path)
        return self.sems[sem_path]

    def run(self, name, functor, args, freq=None, clear_on_fail=False):
        sem = self._get_sem(freq)
        if not sem:
            sem = DummySemaphores()
        if not args:
            args = []
        if sem.has_run(name, freq):
            LOG.debug("%s already ran (freq=%s)", name, freq)
            return (False, None)
        with sem.lock(name, freq, clear_on_fail) as lk:
            if not lk:
                raise LockFailure("Failed to acquire lock for %s" % name)
            else:
                LOG.debug("Running %s using lock (%s)", name, lk)
                if isinstance(args, (dict)):
                    results = functor(**args)
                else:
                    results = functor(*args)
                return (True, results)


class ConfigMerger:
    def __init__(
        self,
        paths=None,
        datasource=None,
        additional_fns=None,
        base_cfg=None,
        include_vendor=True,
    ):
        self._paths = paths
        self._ds = datasource
        self._fns = additional_fns
        self._base_cfg = base_cfg
        self._include_vendor = include_vendor
        # Created on first use
        self._cfg = None

    def _get_datasource_configs(self):
        d_cfgs = []
        if self._ds:
            try:
                ds_cfg = self._ds.get_config_obj()
                if ds_cfg and isinstance(ds_cfg, (dict)):
                    d_cfgs.append(ds_cfg)
            except Exception:
                util.logexc(
                    LOG,
                    "Failed loading of datasource config object from %s",
                    self._ds,
                )
        return d_cfgs

    def _get_env_configs(self):
        e_cfgs = []
        if CFG_ENV_NAME in os.environ:
            e_fn = os.environ[CFG_ENV_NAME]
            try:
                e_cfgs.append(util.read_conf(e_fn))
            except Exception:
                util.logexc(LOG, "Failed loading of env. config from %s", e_fn)
        return e_cfgs

    def _get_instance_configs(self):
        i_cfgs = []
        # If cloud-config was written, pick it up as
        # a configuration file to use when running...
        if not self._paths:
            return i_cfgs

        cc_paths = ["cloud_config"]
        if self._include_vendor:
            # the order is important here: we want vendor2
            #  (dynamic vendor data from OpenStack)
            #  to override vendor (static data from OpenStack)
            cc_paths.append("vendor2_cloud_config")
            cc_paths.append("vendor_cloud_config")

        for cc_p in cc_paths:
            cc_fn = self._paths.get_ipath_cur(cc_p)
            if cc_fn and os.path.isfile(cc_fn):
                try:
                    i_cfgs.append(util.read_conf(cc_fn))
                except PermissionError:
                    LOG.debug(
                        "Skipped loading cloud-config from %s due to"
                        " non-root.",
                        cc_fn,
                    )
                except Exception:
                    util.logexc(
                        LOG, "Failed loading of cloud-config from %s", cc_fn
                    )
        return i_cfgs

    def _read_cfg(self) -> dict:
        # Input config files override
        # env config files which
        # override instance configs
        # which override datasource
        # configs which override
        # base configuration
        cfgs = []
        if self._fns:
            for c_fn in self._fns:
                try:
                    cfgs.append(util.read_conf(c_fn))
                except Exception:
                    util.logexc(
                        LOG, "Failed loading of configuration from %s", c_fn
                    )

        cfgs.extend(self._get_env_configs())
        cfgs.extend(self._get_instance_configs())
        cfgs.extend(self._get_datasource_configs())
        if self._base_cfg:
            cfgs.append(self._base_cfg)
        return util.mergemanydict(cfgs)

    @property
    def cfg(self):
        # None check to avoid empty case causing re-reading
        if self._cfg is None:
            self._cfg = self._read_cfg()
        return self._cfg


class ContentHandlers:
    def __init__(self):
        self.registered = {}
        self.initialized = []

    def __contains__(self, item):
        return self.is_registered(item)

    def __getitem__(self, key):
        return self._get_handler(key)

    def is_registered(self, content_type):
        return content_type in self.registered

    def register(self, mod, initialized=False, overwrite=True):
        types = set()
        for t in mod.list_types():
            if overwrite:
                types.add(t)
            else:
                if not self.is_registered(t):
                    types.add(t)
        for t in types:
            self.registered[t] = mod
        if initialized and mod not in self.initialized:
            self.initialized.append(mod)
        return types

    def _get_handler(self, content_type):
        return self.registered[content_type]

    def items(self):
        return list(self.registered.items())


class Paths(persistence.CloudInitPickleMixin):
    _ci_pkl_version = 1

    def __init__(self, path_cfgs: dict, ds=None):
        self.cfgs = path_cfgs
        # Populate all the initial paths
        self.cloud_dir: str = path_cfgs.get("cloud_dir", "/var/lib/cloud")
        self.docs_dir: str = path_cfgs.get(
            "docs_dir", "/usr/share/doc/cloud-init/"
        )
        self.run_dir: str = path_cfgs.get("run_dir", settings.DEFAULT_RUN_DIR)
        self.instance_link: str = os.path.join(self.cloud_dir, "instance")
        self.boot_finished: str = os.path.join(
            self.instance_link, "boot-finished"
        )
        self.seed_dir: str = os.path.join(self.cloud_dir, "seed")
        # This one isn't joined, since it should just be read-only
        template_dir: str = path_cfgs.get(
            "templates_dir", "/etc/cloud/templates/"
        )
        self.template_tpl: str = os.path.join(template_dir, "%s.tmpl")
        self.lookups = {
            "boothooks": "boothooks",
            "cloud_config": "cloud-config.txt",
            "data": "data",
            "handlers": "handlers",
            # File in which public available instance meta-data is written
            # security-sensitive key values are redacted from this
            # world-readable file
            "instance_data": "instance-data.json",
            # security-sensitive key values are present in this root-readable
            # file
            "instance_data_sensitive": "instance-data-sensitive.json",
            "combined_cloud_config": "combined-cloud-config.json",
            "network_config": "network-config.json",
            "instance_id": ".instance-id",
            "manual_clean_marker": "manual-clean",
            "obj_pkl": "obj.pkl",
            "scripts": "scripts",
            "sem": "sem",
            "userdata": "user-data.txt.i",
            "userdata_raw": "user-data.txt",
            "vendordata": "vendor-data.txt.i",
            "vendordata2": "vendor-data2.txt.i",
            "vendordata2_raw": "vendor-data2.txt",
            "vendordata_raw": "vendor-data.txt",
            "vendor2_cloud_config": "vendor2-cloud-config.txt",
            "vendor_cloud_config": "vendor-cloud-config.txt",
            "vendor_scripts": "scripts/vendor",
            "warnings": "warnings",
            "hotplug.enabled": "hotplug.enabled",
            ".skip-network": ".skip-network",
        }
        # Set when a datasource becomes active
        self.datasource = ds

    def _unpickle(self, ci_pkl_version: int) -> None:
        """Perform deserialization fixes for Paths."""
        if not hasattr(self, "run_dir"):
            # On older versions of cloud-init the Paths class do not
            # have the run_dir attribute. This is problematic because
            # when loading the pickle object on newer versions of cloud-init
            # we will rely on this attribute. To fix that, we are now
            # manually adding that attribute here.
            self.run_dir = Paths(
                path_cfgs=self.cfgs, ds=self.datasource
            ).run_dir
        if "instance_data" not in self.lookups:
            self.lookups["instance_data"] = "instance-data.json"
        if "instance_data_sensitive" not in self.lookups:
            self.lookups["instance_data_sensitive"] = (
                "instance-data-sensitive.json"
            )
        if "combined_cloud_config" not in self.lookups:
            self.lookups["combined_cloud_config"] = (
                "combined-cloud-config.json"
            )
        if "hotplug.enabled" not in self.lookups:
            self.lookups["hotplug.enabled"] = "hotplug.enabled"

    # get_ipath_cur: get the current instance path for an item
    def get_ipath_cur(self, name=None):
        return self._get_path(self.instance_link, name)

    # get_cpath : get the "clouddir" (/var/lib/cloud/<name>)
    # for a name in dirmap
    def get_cpath(self, name=None):
        return self._get_path(self.cloud_dir, name)

    # _get_ipath : get the instance path for a name in pathmap
    # (/var/lib/cloud/instances/<instance>/<name>)
    def _get_ipath(self, name=None):
        if not self.datasource:
            return None
        iid = self.datasource.get_instance_id()
        if iid is None:
            return None
        path_safe_iid = str(iid).replace(os.sep, "_")
        ipath = os.path.join(self.cloud_dir, "instances", path_safe_iid)
        add_on = self.lookups.get(name)
        if add_on:
            ipath = os.path.join(ipath, add_on)
        return ipath

    # get_ipath : get the instance path for a name in pathmap
    # (/var/lib/cloud/instances/<instance>/<name>)
    # returns None + warns if no active datasource....
    def get_ipath(self, name=None):
        ipath = self._get_ipath(name)
        if not ipath:
            LOG.warning(
                "No per instance data available, "
                "is there an datasource/iid set?"
            )
            return None
        else:
            return ipath

    def _get_path(self, base: str, name=None):
        if name is None:
            return base
        return os.path.join(base, self.lookups[name])

    def get_runpath(self, name=None):
        return self._get_path(self.run_dir, name)


# This config parser will not throw when sections don't exist
# and you are setting values on those sections which is useful
# when writing to new options that may not have corresponding
# sections. Also it can default other values when doing gets
# so that if those sections/options do not exist you will
# get a default instead of an error. Another useful case where
# you can avoid catching exceptions that you typically don't
# care about...


class DefaultingConfigParser(RawConfigParser):
    DEF_INT = 0
    DEF_FLOAT = 0.0
    DEF_BOOLEAN = False
    DEF_BASE = None

    def get(self, section, option):
        value = self.DEF_BASE
        try:
            value = RawConfigParser.get(self, section, option)
        except NoSectionError:
            pass
        except NoOptionError:
            pass
        return value

    def set(self, section, option, value=None):
        if not self.has_section(section) and section.lower() != "default":
            self.add_section(section)
        RawConfigParser.set(self, section, option, value)

    def remove_option(self, section, option):
        if self.has_option(section, option):
            RawConfigParser.remove_option(self, section, option)

    def getboolean(self, section, option):
        if not self.has_option(section, option):
            return self.DEF_BOOLEAN
        return RawConfigParser.getboolean(self, section, option)

    def getfloat(self, section, option):
        if not self.has_option(section, option):
            return self.DEF_FLOAT
        return RawConfigParser.getfloat(self, section, option)

    def getint(self, section, option):
        if not self.has_option(section, option):
            return self.DEF_INT
        return RawConfigParser.getint(self, section, option)

    def stringify(self, header=None):
        contents = ""
        outputstream = StringIO()
        self.write(outputstream)
        outputstream.flush()
        contents = outputstream.getvalue()
        if header:
            contents = "\n".join([header, contents, ""])
        return contents