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Filename : cc_lxd.py
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# Copyright (C) 2016 Canonical Ltd.
#
# Author: Wesley Wiedenmeier <wesley.wiedenmeier@canonical.com>
#
# This file is part of cloud-init. See LICENSE file for license information.

"""LXD: configure lxd with ``lxd init`` and optionally lxd-bridge"""

import logging
import os
from textwrap import dedent
from typing import List, Tuple

from cloudinit import safeyaml, subp, util
from cloudinit.cloud import Cloud
from cloudinit.config import Config
from cloudinit.config.schema import MetaSchema, get_meta_doc
from cloudinit.settings import PER_INSTANCE

LOG = logging.getLogger(__name__)

_DEFAULT_NETWORK_NAME = "lxdbr0"


MODULE_DESCRIPTION = """\
This module configures lxd with user specified options using ``lxd init``.
If lxd is not present on the system but lxd configuration is provided, then
lxd will be installed. If the selected storage backend userspace utility is
not installed, it will be installed. If network bridge configuration is
provided, then lxd-bridge will be configured accordingly.
"""

distros = ["ubuntu"]

meta: MetaSchema = {
    "id": "cc_lxd",
    "name": "LXD",
    "title": "Configure LXD with ``lxd init`` and optionally lxd-bridge",
    "description": MODULE_DESCRIPTION,
    "distros": distros,
    "examples": [
        dedent(
            """\
            # Simplest working directory backed LXD configuration
            lxd:
              init:
                storage_backend: dir
            """
        ),
        dedent(
            """\
            # LXD init showcasing cloud-init's LXD config options
            lxd:
              init:
                network_address: 0.0.0.0
                network_port: 8443
                storage_backend: zfs
                storage_pool: datapool
                storage_create_loop: 10
              bridge:
                mode: new
                mtu: 1500
                name: lxdbr0
                ipv4_address: 10.0.8.1
                ipv4_netmask: 24
                ipv4_dhcp_first: 10.0.8.2
                ipv4_dhcp_last: 10.0.8.3
                ipv4_dhcp_leases: 250
                ipv4_nat: true
                ipv6_address: fd98:9e0:3744::1
                ipv6_netmask: 64
                ipv6_nat: true
                domain: lxd
            """
        ),
        dedent(
            """\
            # For more complex non-iteractive LXD configuration of networks,
            # storage_pools, profiles, projects, clusters and core config,
            # `lxd:preseed` config will be passed as stdin to the command:
            #  lxd init --preseed
            # See https://documentation.ubuntu.com/lxd/en/latest/howto/initialize/#non-interactive-configuration or
            # run: lxd init --dump to see viable preseed YAML allowed.
            #
            # Preseed settings configuring the LXD daemon for HTTPS connections
            # on 192.168.1.1 port 9999, a nested profile which allows for
            # LXD nesting on containers and a limited project allowing for
            # RBAC approach when defining behavior for sub projects.
            lxd:
              preseed: |
                config:
                  core.https_address: 192.168.1.1:9999
                networks:
                  - config:
                      ipv4.address: 10.42.42.1/24
                      ipv4.nat: true
                      ipv6.address: fd42:4242:4242:4242::1/64
                      ipv6.nat: true
                    description: ""
                    name: lxdbr0
                    type: bridge
                    project: default
                storage_pools:
                  - config:
                      size: 5GiB
                      source: /var/snap/lxd/common/lxd/disks/default.img
                    description: ""
                    name: default
                    driver: zfs
                profiles:
                  - config: {}
                    description: Default LXD profile
                    devices:
                      eth0:
                        name: eth0
                        network: lxdbr0
                        type: nic
                      root:
                        path: /
                        pool: default
                        type: disk
                    name: default
                  - config: {}
                    security.nesting: true
                    devices:
                      eth0:
                        name: eth0
                        network: lxdbr0
                        type: nic
                      root:
                        path: /
                        pool: default
                        type: disk
                    name: nested
                projects:
                  - config:
                      features.images: true
                      features.networks: true
                      features.profiles: true
                      features.storage.volumes: true
                    description: Default LXD project
                    name: default
                  - config:
                      features.images: false
                      features.networks: true
                      features.profiles: false
                      features.storage.volumes: false
                    description: Limited Access LXD project
                    name: limited


            """  # noqa: E501
        ),
    ],
    "frequency": PER_INSTANCE,
    "activate_by_schema_keys": ["lxd"],
}

__doc__ = get_meta_doc(meta)


def supplemental_schema_validation(
    init_cfg: dict, bridge_cfg: dict, preseed_str: str
):
    """Validate user-provided lxd network and bridge config option values.

    @raises: ValueError describing invalid values provided.
    """
    errors = []
    if not isinstance(init_cfg, dict):
        errors.append(
            f"lxd.init config must be a dictionary. found a"
            f" '{type(init_cfg).__name__}'",
        )

    if not isinstance(bridge_cfg, dict):
        errors.append(
            f"lxd.bridge config must be a dictionary. found a"
            f" '{type(bridge_cfg).__name__}'",
        )

    if not isinstance(preseed_str, str):
        errors.append(
            f"lxd.preseed config must be a string. found a"
            f" '{type(preseed_str).__name__}'",
        )
    if preseed_str and (init_cfg or bridge_cfg):
        incompat_cfg = ["lxd.init"] if init_cfg else []
        incompat_cfg += ["lxd.bridge"] if bridge_cfg else []

        errors.append(
            "Unable to configure LXD. lxd.preseed config can not be provided"
            f" with key(s): {', '.join(incompat_cfg)}"
        )
    if errors:
        raise ValueError(". ".join(errors))


def handle(name: str, cfg: Config, cloud: Cloud, args: list) -> None:
    # Get config
    lxd_cfg = cfg.get("lxd")
    if not lxd_cfg:
        LOG.debug(
            "Skipping module named %s, not present or disabled by cfg", name
        )
        return
    if not isinstance(lxd_cfg, dict):
        raise ValueError(
            f"lxd config must be a dictionary. found a"
            f" '{type(lxd_cfg).__name__}'"
        )

    # Grab the configuration
    init_cfg = lxd_cfg.get("init", {})
    preseed_str = lxd_cfg.get("preseed", "")
    bridge_cfg = lxd_cfg.get("bridge", {})
    supplemental_schema_validation(init_cfg, bridge_cfg, preseed_str)

    if not subp.which("lxd"):
        try:
            subp.subp(["snap", "install", "lxd"])
        except subp.ProcessExecutionError as e:
            raise RuntimeError(
                "Failed to install lxd from snap: %s" % e
            ) from e
    packages = get_required_packages(init_cfg, preseed_str)
    if len(packages):
        try:
            cloud.distro.install_packages(packages)
        except subp.ProcessExecutionError as exc:
            LOG.warning("failed to install packages %s: %s", packages, exc)
            return

    subp.subp(["lxd", "waitready", "--timeout=300"])
    if preseed_str:
        subp.subp(["lxd", "init", "--preseed"], data=preseed_str)
        return
    # Set up lxd if init config is given
    if init_cfg:
        # type is known, number of elements is not
        # in the case of the ubuntu+lvm backend workaround
        init_keys: Tuple[str, ...] = (
            "network_address",
            "network_port",
            "storage_backend",
            "storage_create_device",
            "storage_create_loop",
            "storage_pool",
            "trust_password",
        )

        # Bug https://bugs.launchpad.net/ubuntu/+source/linux-kvm/+bug/1982780
        kernel = util.system_info()["uname"][2]
        if init_cfg["storage_backend"] == "lvm" and not os.path.exists(
            f"/lib/modules/{kernel}/kernel/drivers/md/dm-thin-pool.ko"
        ):
            LOG.warning(
                "cloud-init doesn't use thinpool by default on Ubuntu due to "
                "LP #1982780. This behavior will change in the future.",
            )
            subp.subp(
                [
                    "lxc",
                    "storage",
                    "create",
                    "default",
                    "lvm",
                    "lvm.use_thinpool=false",
                ]
            )

            # Since we're manually setting use_thinpool=false
            # filter it from the lxd init commands, don't configure
            # storage twice
            init_keys = tuple(
                key for key in init_keys if key != "storage_backend"
            )

        cmd = ["lxd", "init", "--auto"]
        for k in init_keys:
            if init_cfg.get(k):
                cmd.extend(
                    ["--%s=%s" % (k.replace("_", "-"), str(init_cfg[k]))]
                )
        subp.subp(cmd)

    # Set up lxd-bridge if bridge config is given
    dconf_comm = "debconf-communicate"
    if bridge_cfg:
        net_name = bridge_cfg.get("name", _DEFAULT_NETWORK_NAME)
        if os.path.exists("/etc/default/lxd-bridge") and subp.which(
            dconf_comm
        ):
            # Bridge configured through packaging

            debconf = bridge_to_debconf(bridge_cfg)

            # Update debconf database
            try:
                LOG.debug("Setting lxd debconf via %s", dconf_comm)
                data = (
                    "\n".join(
                        ["set %s %s" % (k, v) for k, v in debconf.items()]
                    )
                    + "\n"
                )
                subp.subp(["debconf-communicate"], data=data)
            except Exception:
                util.logexc(
                    LOG, "Failed to run '%s' for lxd with" % dconf_comm
                )

            # Remove the existing configuration file (forces re-generation)
            util.del_file("/etc/default/lxd-bridge")

            # Run reconfigure
            LOG.debug("Running dpkg-reconfigure for lxd")
            subp.subp(["dpkg-reconfigure", "lxd", "--frontend=noninteractive"])
        else:
            # Built-in LXD bridge support
            cmd_create, cmd_attach = bridge_to_cmd(bridge_cfg)
            maybe_cleanup_default(
                net_name=net_name,
                did_init=bool(init_cfg),
                create=bool(cmd_create),
                attach=bool(cmd_attach),
            )
            if cmd_create:
                LOG.debug("Creating lxd bridge: %s", " ".join(cmd_create))
                _lxc(cmd_create)

            if cmd_attach:
                LOG.debug(
                    "Setting up default lxd bridge: %s", " ".join(cmd_attach)
                )
                _lxc(cmd_attach)

    elif bridge_cfg:
        raise RuntimeError(
            "Unable to configure lxd bridge without %s." + dconf_comm
        )


def bridge_to_debconf(bridge_cfg):
    debconf = {}

    if bridge_cfg.get("mode") == "none":
        debconf["lxd/setup-bridge"] = "false"
        debconf["lxd/bridge-name"] = ""

    elif bridge_cfg.get("mode") == "existing":
        debconf["lxd/setup-bridge"] = "false"
        debconf["lxd/use-existing-bridge"] = "true"
        debconf["lxd/bridge-name"] = bridge_cfg.get("name")

    elif bridge_cfg.get("mode") == "new":
        debconf["lxd/setup-bridge"] = "true"
        if bridge_cfg.get("name"):
            debconf["lxd/bridge-name"] = bridge_cfg.get("name")

        if bridge_cfg.get("ipv4_address"):
            debconf["lxd/bridge-ipv4"] = "true"
            debconf["lxd/bridge-ipv4-address"] = bridge_cfg.get("ipv4_address")
            debconf["lxd/bridge-ipv4-netmask"] = bridge_cfg.get("ipv4_netmask")
            debconf["lxd/bridge-ipv4-dhcp-first"] = bridge_cfg.get(
                "ipv4_dhcp_first"
            )
            debconf["lxd/bridge-ipv4-dhcp-last"] = bridge_cfg.get(
                "ipv4_dhcp_last"
            )
            debconf["lxd/bridge-ipv4-dhcp-leases"] = bridge_cfg.get(
                "ipv4_dhcp_leases"
            )
            debconf["lxd/bridge-ipv4-nat"] = bridge_cfg.get("ipv4_nat", "true")

        if bridge_cfg.get("ipv6_address"):
            debconf["lxd/bridge-ipv6"] = "true"
            debconf["lxd/bridge-ipv6-address"] = bridge_cfg.get("ipv6_address")
            debconf["lxd/bridge-ipv6-netmask"] = bridge_cfg.get("ipv6_netmask")
            debconf["lxd/bridge-ipv6-nat"] = bridge_cfg.get(
                "ipv6_nat", "false"
            )

        if bridge_cfg.get("domain"):
            debconf["lxd/bridge-domain"] = bridge_cfg.get("domain")

    else:
        raise RuntimeError('invalid bridge mode "%s"' % bridge_cfg.get("mode"))

    return debconf


def bridge_to_cmd(bridge_cfg):
    if bridge_cfg.get("mode") == "none":
        return None, None

    bridge_name = bridge_cfg.get("name", _DEFAULT_NETWORK_NAME)
    cmd_create = []
    cmd_attach = ["network", "attach-profile", bridge_name, "default", "eth0"]

    if bridge_cfg.get("mode") == "existing":
        return None, cmd_attach

    if bridge_cfg.get("mode") != "new":
        raise RuntimeError('invalid bridge mode "%s"' % bridge_cfg.get("mode"))

    cmd_create = ["network", "create", bridge_name]

    if bridge_cfg.get("ipv4_address") and bridge_cfg.get("ipv4_netmask"):
        cmd_create.append(
            "ipv4.address=%s/%s"
            % (bridge_cfg.get("ipv4_address"), bridge_cfg.get("ipv4_netmask"))
        )

        if bridge_cfg.get("ipv4_nat", "true") == "true":
            cmd_create.append("ipv4.nat=true")

        if bridge_cfg.get("ipv4_dhcp_first") and bridge_cfg.get(
            "ipv4_dhcp_last"
        ):
            dhcp_range = "%s-%s" % (
                bridge_cfg.get("ipv4_dhcp_first"),
                bridge_cfg.get("ipv4_dhcp_last"),
            )
            cmd_create.append("ipv4.dhcp.ranges=%s" % dhcp_range)
    else:
        cmd_create.append("ipv4.address=none")

    if bridge_cfg.get("ipv6_address") and bridge_cfg.get("ipv6_netmask"):
        cmd_create.append(
            "ipv6.address=%s/%s"
            % (bridge_cfg.get("ipv6_address"), bridge_cfg.get("ipv6_netmask"))
        )

        if bridge_cfg.get("ipv6_nat", "false") == "true":
            cmd_create.append("ipv6.nat=true")

    else:
        cmd_create.append("ipv6.address=none")

    if bridge_cfg.get("domain"):
        cmd_create.append("dns.domain=%s" % bridge_cfg.get("domain"))

    # if the default schema value is passed (-1) don't pass arguments
    # to LXD. Use LXD defaults unless user manually sets a number
    mtu = bridge_cfg.get("mtu", -1)
    if mtu != -1:
        cmd_create.append(f"bridge.mtu={mtu}")

    return cmd_create, cmd_attach


def _lxc(cmd):
    env = {
        "LC_ALL": "C",
        "HOME": os.environ.get("HOME", "/root"),
        "USER": os.environ.get("USER", "root"),
    }
    subp.subp(["lxc"] + list(cmd) + ["--force-local"], update_env=env)


def maybe_cleanup_default(
    net_name, did_init, create, attach, profile="default", nic_name="eth0"
):
    """Newer versions of lxc (3.0.1+) create a lxdbr0 network when
    'lxd init --auto' is run.  Older versions did not.

    By removing any that lxd-init created, we simply leave the add/attach
    code intact.

    https://github.com/canonical/lxd/issues/4649"""
    if net_name != _DEFAULT_NETWORK_NAME or not did_init:
        return

    fail_assume_enoent = "failed. Assuming it did not exist."
    succeeded = "succeeded."
    if create:
        msg = "Detach of lxd network '%s' from profile '%s' %s"
        try:
            _lxc(["network", "detach-profile", net_name, profile])
            LOG.debug(msg, net_name, profile, succeeded)
        except subp.ProcessExecutionError as e:
            if e.exit_code != 1:
                raise e
            LOG.debug(msg, net_name, profile, fail_assume_enoent)
        else:
            msg = "Deletion of lxd network '%s' %s"
            _lxc(["network", "delete", net_name])
            LOG.debug(msg, net_name, succeeded)

    if attach:
        msg = "Removal of device '%s' from profile '%s' %s"
        try:
            _lxc(["profile", "device", "remove", profile, nic_name])
            LOG.debug(msg, nic_name, profile, succeeded)
        except subp.ProcessExecutionError as e:
            if e.exit_code != 1:
                raise e
            LOG.debug(msg, nic_name, profile, fail_assume_enoent)


def get_required_packages(init_cfg: dict, preseed_str: str) -> List[str]:
    """identify required packages for install"""
    packages = []
    # binary for pool creation must be available for the requested backend:
    # zfs, lvcreate, mkfs.btrfs
    storage_drivers: List[str] = []
    preseed_cfg: dict = {}
    if "storage_backend" in init_cfg:
        storage_drivers.append(init_cfg["storage_backend"])
    if preseed_str and "storage_pools" in preseed_str:
        # Assume correct YAML preseed format
        try:
            preseed_cfg = safeyaml.load(preseed_str)
        except (safeyaml.YAMLError, TypeError, ValueError):
            LOG.warning(
                "lxd.preseed string value is not YAML. "
                " Unable to determine required storage driver packages to"
                " support storage_pools config."
            )
    for storage_pool in preseed_cfg.get("storage_pools", []):
        if storage_pool.get("driver"):
            storage_drivers.append(storage_pool["driver"])
    if "zfs" in storage_drivers and not subp.which("zfs"):
        packages.append("zfsutils-linux")
    if "lvm" in storage_drivers and not subp.which("lvcreate"):
        packages.append("lvm2")
    if "btrfs" in storage_drivers and not subp.which("mkfs.btrfs"):
        packages.append("btrfs-progs")
    return packages