kubecluster.py

from __future__ import annotations

import asyncio
import atexit
from contextlib import suppress
from enum import Enum
import getpass
import logging
import os
import time
from typing import ClassVar
import warnings
import weakref
import uuid

from rich import box
from rich.live import Live
from rich.table import Table
from rich.console import Group
from rich.panel import Panel
from rich.spinner import Spinner
import pykube.exceptions
import kubernetes_asyncio as kubernetes
import yaml

import dask.config
from distributed.core import Status, rpc
from distributed.deploy import Cluster
from distributed.utils import (
    Log,
    Logs,
    TimeoutError,
    format_dashboard_link,
)
from kubernetes_asyncio.client.exceptions import ApiException

from dask_kubernetes.common.auth import ClusterAuth

from dask_kubernetes.common.networking import (
    get_scheduler_address,
    wait_for_scheduler,
    wait_for_scheduler_comm,
)
from dask_kubernetes.common.utils import get_current_namespace
from dask_kubernetes.aiopykube import HTTPClient, KubeConfig
from dask_kubernetes.aiopykube.dask import DaskCluster, DaskWorkerGroup
from dask_kubernetes.aiopykube.objects import Pod, Service
from dask_kubernetes.exceptions import CrashLoopBackOffError, SchedulerStartupError

logger = logging.getLogger(__name__)


class CreateMode(Enum):
    CREATE_ONLY = "CREATE_ONLY"
    CREATE_OR_CONNECT = "CREATE_OR_CONNECT"
    CONNECT_ONLY = "CONNECT_ONLY"


class KubeCluster(Cluster):
    """Launch a Dask Cluster on Kubernetes using the Operator

    This cluster manager creates a Dask cluster by deploying
    the necessary kubernetes resources the Dask Operator needs
    to create pods. It can also connect to an existing cluster
    by providing the name of the cluster.

    Parameters
    ----------
    name: str (required)
        Name given the Dask cluster.
    namespace: str (optional)
        Namespace in which to launch the workers.
        Defaults to current namespace if available or "default"
    image: str (optional)
        Image to run in Scheduler and Worker Pods.
    n_workers: int
        Number of workers on initial launch.
        Use ``scale`` to change this number in the future
    resources: Dict[str, str]
    env: List[dict] | Dict[str, str]
        List of environment variables to pass to worker pod.
        Can be a list of dicts using the same structure as k8s envs
        or a single dictionary of key/value pairs
    worker_command: List[str] | str
        The command to use when starting the worker.
        If command consists of multiple words it should be passed as a list of strings.
        Defaults to ``"dask-worker"``.
    auth: List[ClusterAuth] (optional)
        Configuration methods to attempt in order.  Defaults to
        ``[InCluster(), KubeConfig()]``.
    port_forward_cluster_ip: bool (optional)
        If the chart uses ClusterIP type services, forward the
        ports locally. If you are running it locally it should
        be the port you are forwarding to ``<port>``.
    create_mode: CreateMode (optional)
        How to handle cluster creation if the cluster resource already exists.
        Default behaviour is to create a new clustser if one with that name
        doesn't exist, or connect to an existing one if it does.
        You can also set ``CreateMode.CREATE_ONLY`` to raise an exception if a cluster
        with that name already exists. Or ``CreateMode.CONNECT_ONLY`` to raise an exception
        if a cluster with that name doesn't exist.
    shutdown_on_close: bool (optional)
        Whether or not to delete the cluster resource when this object is closed.
        Defaults to ``True`` when creating a cluster and ``False`` when connecting to an existing one.
    resource_timeout: int (optional)
        Time in seconds to wait for Kubernetes resources to enter their expected state.
        Example: If the ``DaskCluster`` resource that gets created isn't moved into a known ``status.phase``
        by the controller then it is likely the controller isn't running or is malfunctioning and we time
        out and clean up with a useful error.
        Example 2: If the scheduler Pod enters a ``CrashBackoffLoop`` state for longer than this timeout we
        give up with a useful error.
        Defaults to ``60`` seconds.
    scheduler_service_type: str (optional)
        Kubernetes service type to use for the scheduler. Defaults to ``ClusterIP``.
    custom_cluster_spec: str | dict (optional)
        Path to a YAML manifest or a dictionary representation of a ``DaskCluster`` resource object which will be
        used to create the cluster instead of generating one from the other keyword arguments.
    scheduler_forward_port: int (optional)
        The port to use when forwarding the scheduler dashboard. Will utilize a random port by default

    **kwargs: dict
        Additional keyword arguments to pass to LocalCluster

    Examples
    --------
    >>> from dask_kubernetes.operator import KubeCluster
    >>> cluster = KubeCluster(name="foo")

    You can add another group of workers (default is 3 workers)
    >>> cluster.add_worker_group('additional', n=4)

    You can then resize the cluster with the scale method
    >>> cluster.scale(10)

    And optionally scale a specific worker group
    >>> cluster.scale(10, worker_group='additional')

    You can also resize the cluster adaptively and give
    it a range of workers
    >>> cluster.adapt(20, 50)

    You can pass this cluster directly to a Dask client
    >>> from dask.distributed import Client
    >>> client = Client(cluster)

    You can also access cluster logs
    >>> cluster.get_logs()

    You can also connect to an existing cluster
    >>> existing_cluster = KubeCluster.from_name(name="ialreadyexist")

    See Also
    --------
    KubeCluster.from_name
    """

    _instances: ClassVar[weakref.WeakSet[KubeCluster]] = weakref.WeakSet()

    def __init__(
        self,
        *,
        name=None,
        namespace=None,
        image=None,
        n_workers=None,
        resources=None,
        env=None,
        worker_command=None,
        auth=ClusterAuth.DEFAULT,
        port_forward_cluster_ip=None,
        create_mode=None,
        shutdown_on_close=None,
        resource_timeout=None,
        scheduler_service_type=None,
        custom_cluster_spec=None,
        scheduler_forward_port=None,
        **kwargs,
    ):

        name = dask.config.get("kubernetes.name", override_with=name)
        self.namespace = (
            dask.config.get("kubernetes.namespace", override_with=namespace)
            or get_current_namespace()
        )
        self.image = dask.config.get("kubernetes.image", override_with=image)
        self.n_workers = dask.config.get(
            "kubernetes.count.start", override_with=n_workers
        )
        if dask.config.get("kubernetes.count.max"):
            warnings.warn(
                "Setting a maximum number of workers is no longer supported. "
                "Please use Kubernetes Resource Quotas instead."
            )
        self.resources = dask.config.get(
            "kubernetes.resources", override_with=resources
        )
        self.env = dask.config.get("kubernetes.env", override_with=env)
        self.worker_command = dask.config.get(
            "kubernetes.worker-command", override_with=worker_command
        )
        self.auth = auth
        self.port_forward_cluster_ip = dask.config.get(
            "kubernetes.port-forward-cluster-ip", override_with=port_forward_cluster_ip
        )
        self.create_mode = dask.config.get(
            "kubernetes.create-mode", override_with=create_mode
        )
        self.shutdown_on_close = dask.config.get(
            "kubernetes.shutdown-on-close", override_with=shutdown_on_close
        )
        self._resource_timeout = dask.config.get(
            "kubernetes.resource-timeout", override_with=resource_timeout
        )
        self._custom_cluster_spec = dask.config.get(
            "kubernetes.custom-cluster-spec", override_with=custom_cluster_spec
        )
        self.scheduler_service_type = dask.config.get(
            "kubernetes.scheduler-service-type", override_with=scheduler_service_type
        )
        self.scheduler_forward_port = dask.config.get(
            "kubernetes.scheduler-forward-port", override_with=scheduler_forward_port
        )

        if self._custom_cluster_spec:
            if isinstance(self._custom_cluster_spec, str):
                with open(self._custom_cluster_spec) as f:
                    self._custom_cluster_spec = yaml.safe_load(f.read())
            name = self._custom_cluster_spec["metadata"]["name"]

        if isinstance(self.worker_command, str):
            self.worker_command = self.worker_command.split(" ")

        try:
            # Validate `resources` param is a dictionary whose
            # keys must either be 'limits' or 'requests'
            assert isinstance(
                self.resources, dict
            ), f"resources must be dict type, found {type(resources)}"
            for field in self.resources:
                if field in ("limits", "requests"):
                    assert isinstance(
                        self.resources[field], dict
                    ), f"key of '{field}' must be dict type"
                else:
                    raise ValueError(f"resources has unknown field '{field}'")
        except AssertionError as e:
            raise TypeError from e

        name = name.format(
            user=getpass.getuser(), uuid=str(uuid.uuid4())[:10], **os.environ
        )
        self.k8s_api = HTTPClient(KubeConfig.from_env())
        self._instances.add(self)
        self._rich_spinner = Spinner("dots", speed=0.5)
        self._startup_component_status = {}

        super().__init__(name=name, **kwargs)
        if not self.asynchronous:
            self._loop_runner.start()
            self.sync(self._start)

    def _log(self, log):
        temp = self.quiet
        self.quiet = True
        super()._log(log)
        self.quiet = temp

    @property
    def dashboard_link(self):
        host = self.scheduler_address.split("://")[1].split("/")[0].split(":")[0]
        return format_dashboard_link(host, self.forwarded_dashboard_port)

    async def _start(self):
        try:
            watch_component_status_task = asyncio.create_task(
                self._watch_component_status()
            )
            if not self.quiet:
                show_rich_output_task = asyncio.create_task(self._show_rich_output())
            await ClusterAuth.load_first(self.auth)
            cluster_exists = (await self._get_cluster()) is not None

            if cluster_exists and self.create_mode == CreateMode.CREATE_ONLY:
                raise ValueError(
                    f"Cluster {self.name} already exists and create mode is '{CreateMode.CREATE_ONLY}'"
                )
            elif cluster_exists:
                self._log("Connecting to existing cluster")
                await self._connect_cluster()
            elif not cluster_exists and self.create_mode == CreateMode.CONNECT_ONLY:
                raise ValueError(
                    f"Cluster {self.name} doesn't already exist and create "
                    f"mode is '{CreateMode.CONNECT_ONLY}'"
                )
            else:
                self._log("Creating cluster")
                await self._create_cluster()

            await super()._start()
            self._log(f"Ready, dashboard available at {self.dashboard_link}")
        finally:
            watch_component_status_task.cancel()
            if not self.quiet:
                show_rich_output_task.cancel()

    def __await__(self):
        async def _():
            if self.status == Status.created:
                await self._start()
            return self

        return _().__await__()

    async def _create_cluster(self):
        if self.shutdown_on_close is None:
            self.shutdown_on_close = True
        async with kubernetes.client.api_client.ApiClient() as api_client:
            core_api = kubernetes.client.CoreV1Api(api_client)
            custom_objects_api = kubernetes.client.CustomObjectsApi(api_client)

            if not self._custom_cluster_spec:
                self._log("Generating cluster spec")
                data = make_cluster_spec(
                    name=self.name,
                    env=self.env,
                    resources=self.resources,
                    worker_command=self.worker_command,
                    n_workers=self.n_workers,
                    image=self.image,
                    scheduler_service_type=self.scheduler_service_type,
                )
            else:
                data = self._custom_cluster_spec
            try:
                self._log("Creating DaskCluster object")
                await custom_objects_api.create_namespaced_custom_object(
                    group="kubernetes.dask.org",
                    version="v1",
                    plural="daskclusters",
                    namespace=self.namespace,
                    body=data,
                )
            except kubernetes.client.ApiException as e:
                if e.status == 404:
                    raise RuntimeError(
                        "Failed to create DaskCluster resource."
                        "Are the Dask Custom Resource Definitions installed? "
                        "https://kubernetes.dask.org/en/latest/operator.html#installing-the-operator"
                    ) from e
                else:
                    raise e

            try:
                self._log("Waiting for controller to action cluster")
                await self._wait_for_controller()
            except TimeoutError as e:
                await self._close()
                raise e
            try:
                self._log("Waiting for scheduler pod")
                await wait_for_scheduler(
                    self.k8s_api,
                    self.name,
                    self.namespace,
                    timeout=self._resource_timeout,
                )
            except CrashLoopBackOffError as e:
                logs = await self._get_logs()
                await self._close()
                raise SchedulerStartupError(
                    "Scheduler failed to start.",
                    "Scheduler Pod logs:",
                    logs[self.name + "-scheduler"],
                ) from e
            self._log("Waiting for scheduler service")
            await wait_for_service(core_api, f"{self.name}-scheduler", self.namespace)
            scheduler_address = await self._get_scheduler_address()
            self._log("Connecting to scheduler")
            await wait_for_scheduler_comm(scheduler_address)
            self.scheduler_comm = rpc(scheduler_address)
            local_port = self.scheduler_forward_port
            if local_port:
                local_port = int(local_port)
            self._log("Getting dashboard URL")
            dashboard_address = await get_scheduler_address(
                f"{self.name}-scheduler",
                self.namespace,
                port_name="http-dashboard",
                port_forward_cluster_ip=self.port_forward_cluster_ip,
                local_port=local_port,
            )
            self.forwarded_dashboard_port = dashboard_address.split(":")[-1]

    async def _connect_cluster(self):
        if self.shutdown_on_close is None:
            self.shutdown_on_close = False
        async with kubernetes.client.api_client.ApiClient() as api_client:
            core_api = kubernetes.client.CoreV1Api(api_client)
            cluster_spec = await self._get_cluster()
            container_spec = cluster_spec["spec"]["worker"]["spec"]["containers"][0]
            self.image = container_spec["image"]
            self.n_workers = cluster_spec["spec"]["worker"]["replicas"]
            if "resources" in container_spec:
                self.resources = container_spec["resources"]
            else:
                self.resources = None
            if "env" in container_spec:
                self.env = container_spec["env"]
            else:
                self.env = {}
            service_name = f"{cluster_spec['metadata']['name']}-scheduler"
            self._log("Waiting for scheduler pod")
            await wait_for_scheduler(
                self.k8s_api, self.name, self.namespace, timeout=self._resource_timeout
            )
            self._log("Waiting for scheduler service")
            await wait_for_service(core_api, service_name, self.namespace)
            scheduler_address = await self._get_scheduler_address()
            self._log("Connecting to scheduler")
            await wait_for_scheduler_comm(scheduler_address)
            self.scheduler_comm = rpc(scheduler_address)
            local_port = self.scheduler_forward_port
            if local_port:
                local_port = int(local_port)
            self._log("Getting dashboard URL")
            dashboard_address = await get_scheduler_address(
                service_name,
                self.namespace,
                port_name="http-dashboard",
                port_forward_cluster_ip=self.port_forward_cluster_ip,
                local_port=local_port,
            )
            self.forwarded_dashboard_port = dashboard_address.split(":")[-1]

    async def _get_cluster(self):
        async with kubernetes.client.api_client.ApiClient() as api_client:
            custom_objects_api = kubernetes.client.CustomObjectsApi(api_client)
            try:
                return await custom_objects_api.get_namespaced_custom_object(
                    group="kubernetes.dask.org",
                    version="v1",
                    plural="daskclusters",
                    namespace=self.namespace,
                    name=self.name,
                )
            except kubernetes.client.exceptions.ApiException as e:
                return None

    async def _get_scheduler_address(self):
        address = await get_scheduler_address(
            f"{self.name}-scheduler",
            self.namespace,
            port_forward_cluster_ip=self.port_forward_cluster_ip,
        )
        return address

    async def _wait_for_controller(self):
        """Wait for the operator to set the status.phase."""
        start = time.time()
        while start + self._resource_timeout > time.time():
            cluster = await DaskCluster.objects(
                self.k8s_api, namespace=self.namespace
            ).get_by_name(self.name)
            if (
                "status" in cluster.obj
                and "phase" in cluster.obj["status"]
                and cluster.obj["status"]["phase"] == "Running"
            ):
                return
            await asyncio.sleep(0.25)
        raise TimeoutError(
            f"Dask Cluster resource not actioned after {self._resource_timeout} seconds, is the Dask Operator running?"
        )

    async def _watch_component_status(self):
        while True:
            # Get DaskCluster status
            with suppress(pykube.exceptions.ObjectDoesNotExist):
                cluster = await DaskCluster.objects(
                    self.k8s_api, namespace=self.namespace
                ).get_by_name(self.name)
                self._startup_component_status["cluster"] = cluster.obj["status"][
                    "phase"
                ]

            # Get Scheduler Pod status
            with suppress(pykube.exceptions.ObjectDoesNotExist):
                pod = await Pod.objects(
                    self.k8s_api, namespace=self.namespace
                ).get_by_name(self.name + "-scheduler")
                phase = pod.obj["status"]["phase"]
                if phase == "Running":
                    conditions = {
                        c["type"]: c["status"] for c in pod.obj["status"]["conditions"]
                    }
                    if "Ready" not in conditions or conditions["Ready"] != "True":
                        phase = "Health Checking"
                    if "containerStatuses" in pod.obj["status"]:
                        for container in pod.obj["status"]["containerStatuses"]:
                            if "waiting" in container["state"]:
                                phase = container["state"]["waiting"]["reason"]

                self._startup_component_status["schedulerpod"] = phase

            # Get Scheduler Service status
            with suppress(pykube.exceptions.ObjectDoesNotExist):
                await Service.objects(self.k8s_api).get_by_name(
                    self.name + "-scheduler"
                )
                self._startup_component_status["schedulerservice"] = "Created"

            # Get DaskWorkerGroup status
            with suppress(pykube.exceptions.ObjectDoesNotExist):
                await DaskWorkerGroup.objects(
                    self.k8s_api, namespace=self.namespace
                ).get_by_name(self.name + "-default")
                self._startup_component_status["workergroup"] = "Created"

            await asyncio.sleep(1)

    async def generate_rich_output(self):
        table = Table(show_header=False, box=box.SIMPLE, expand=True)
        table.add_column("Component")
        table.add_column("Status", justify="right")

        for (label, component) in [
            ("DaskCluster", "cluster"),
            ("Scheduler Pod", "schedulerpod"),
            ("Scheduler Service", "schedulerservice"),
            ("Default Worker Group", "workergroup"),
        ]:
            try:
                status = self._startup_component_status[component]
            except KeyError:
                status = "-"
            if status in ["Running", "Created"]:
                status = "[green]" + status
            if status in ["Pending", "Health Checking"]:
                status = "[yellow]" + status
            if status in ["CrashLoopBackOff", "Error"]:
                status = "[red]" + status
            table.add_row(label, status)

        if self._cluster_manager_logs:
            self._rich_spinner.update(text=self._cluster_manager_logs[-1][1])
        return Panel(
            Group(table, self._rich_spinner),
            title=f"Creating KubeCluster [magenta]'{self.name}'",
            width=80,
        )

    async def _show_rich_output(self):
        with Live(await self.generate_rich_output(), auto_refresh=False) as live:
            while True:
                await asyncio.sleep(0.25)
                live.update(await self.generate_rich_output(), refresh=True)

    def get_logs(self):
        """Get logs for Dask scheduler and workers.

        Examples
        --------
        >>> cluster.get_logs()
        {'foo': ...,
        'foo-default-worker-0269dbfa0cfd4a22bcd9d92ae032f4d2': ...,
        'foo-default-worker-7c1ccb04cd0e498fb21babaedd00e5d4': ...,
        'foo-default-worker-d65bee23bdae423b8d40c5da7a1065b6': ...}
        Each log will be a string of all logs for that container. To view
        it is recommeded that you print each log.
        >>> print(cluster.get_logs()["testdask-scheduler-5c8ffb6b7b-sjgrg"])
        ...
        distributed.scheduler - INFO - -----------------------------------------------
        distributed.scheduler - INFO - Clear task state
        distributed.scheduler - INFO -   Scheduler at:   tcp://10.244.0.222:8786
        distributed.scheduler - INFO -   dashboard at:                     :8787
        ...
        """
        return self.sync(self._get_logs)

    async def _get_logs(self):
        async with kubernetes.client.api_client.ApiClient() as api_client:
            core_api = kubernetes.client.CoreV1Api(api_client)
            logs = Logs()

            pods = await core_api.list_namespaced_pod(
                namespace=self.namespace,
                label_selector=f"dask.org/cluster-name={self.name}",
            )

            for pod in pods.items:
                if "scheduler" in pod.metadata.name or "worker" in pod.metadata.name:
                    try:
                        if pod.status.phase != "Running":
                            raise ValueError(
                                f"Cannot get logs for pod with status {pod.status.phase}.",
                            )
                        log = Log(
                            await core_api.read_namespaced_pod_log(
                                pod.metadata.name, pod.metadata.namespace
                            )
                        )
                    except (ValueError, kubernetes.client.exceptions.ApiException):
                        log = Log(f"Cannot find logs. Pod is {pod.status.phase}.")
                logs[pod.metadata.name] = log

        return logs

    def add_worker_group(
        self,
        name,
        n_workers=3,
        image=None,
        resources=None,
        worker_command=None,
        env=None,
        custom_spec=None,
    ):
        """Create a dask worker group by name

        Parameters
        ----------
        name: str
            Name of the worker group
        n_workers: int
            Number of workers on initial launch.
            Use ``.scale(n_workers, worker_group=name)`` to change this number in the future.
        image: str (optional)
            Image to run in Scheduler and Worker Pods.
            If ommitted will use the cluster default.
        resources: Dict[str, str]
            Resources to be passed to the underlying pods.
            If ommitted will use the cluster default.
        env: List[dict]
            List of environment variables to pass to worker pod.
            If ommitted will use the cluster default.
        custom_spec: dict (optional)
            A dictionary representation of a worker spec which will be used to create the ``DaskWorkerGroup`` instead
            of generating one from the other keyword arguments.

        Examples
        --------
        >>> cluster.add_worker_group("high-mem-workers", n_workers=5)
        """
        return self.sync(
            self._add_worker_group,
            name=name,
            n_workers=n_workers,
            image=image,
            resources=resources,
            worker_command=worker_command,
            env=env,
            custom_spec=custom_spec,
        )

    async def _add_worker_group(
        self,
        name,
        n_workers=3,
        image=None,
        resources=None,
        worker_command=None,
        env=None,
        custom_spec=None,
    ):
        if custom_spec is not None:
            spec = custom_spec
        else:
            spec = make_worker_spec(
                env=env or self.env,
                resources=resources or self.resources,
                worker_command=worker_command or self.worker_command,
                n_workers=n_workers or self.n_workers,
                image=image or self.image,
            )
            spec["cluster"] = self.name
        data = {
            "apiVersion": "kubernetes.dask.org/v1",
            "kind": "DaskWorkerGroup",
            "metadata": {"name": f"{self.name}-{name}"},
            "spec": {
                "cluster": f"{self.name}",
                "worker": spec,
            },
        }

        async with kubernetes.client.api_client.ApiClient() as api_client:
            custom_objects_api = kubernetes.client.CustomObjectsApi(api_client)
            await custom_objects_api.create_namespaced_custom_object(
                group="kubernetes.dask.org",
                version="v1",
                plural="daskworkergroups",
                namespace=self.namespace,
                body=data,
            )

    def delete_worker_group(self, name):
        """Delete a dask worker group by name

        Parameters
        ----------
        name: str
            Name of the worker group

        Examples
        --------
        >>> cluster.delete_worker_group("high-mem-workers")
        """
        return self.sync(self._delete_worker_group, name)

    async def _delete_worker_group(self, name):
        async with kubernetes.client.api_client.ApiClient() as api_client:
            custom_objects_api = kubernetes.client.CustomObjectsApi(api_client)
            await custom_objects_api.delete_namespaced_custom_object(
                group="kubernetes.dask.org",
                version="v1",
                plural="daskworkergroups",
                namespace=self.namespace,
                name=f"{self.name}-{name}",
            )

    def close(self, timeout=3600):
        """Delete the dask cluster"""
        return self.sync(self._close, timeout=timeout)

    async def _close(self, timeout=None):
        await super()._close()
        if self.shutdown_on_close:
            async with kubernetes.client.api_client.ApiClient() as api_client:
                custom_objects_api = kubernetes.client.CustomObjectsApi(api_client)
                try:
                    await custom_objects_api.delete_namespaced_custom_object(
                        group="kubernetes.dask.org",
                        version="v1",
                        plural="daskclusters",
                        namespace=self.namespace,
                        name=self.name,
                    )
                except ApiException as e:
                    if e.reason == "Not Found":
                        logger.warning(
                            "Failed to delete DaskCluster, looks like it has already been deleted."
                        )
                    else:
                        raise
            start = time.time()
            while (await self._get_cluster()) is not None:
                if time.time() > start + timeout:
                    raise TimeoutError(
                        f"Timed out deleting cluster resource {self.name}"
                    )
                await asyncio.sleep(1)

    def scale(self, n, worker_group="default"):
        """Scale cluster to n workers

        Parameters
        ----------
        n : int
            Target number of workers
        worker_group : str
            Worker group to scale

        Examples
        --------
        >>> cluster.scale(10)  # scale cluster to ten workers
        >>> cluster.scale(7, worker_group="high-mem-workers") # scale worker group high-mem-workers to seven workers
        """

        return self.sync(self._scale, n, worker_group)

    async def _scale(self, n, worker_group="default"):
        async with kubernetes.client.api_client.ApiClient() as api_client:
            custom_objects_api = kubernetes.client.CustomObjectsApi(api_client)
            custom_objects_api.api_client.set_default_header(
                "content-type", "application/merge-patch+json"
            )
            # Disable adaptivity if enabled
            with suppress(kubernetes.client.ApiException):
                await custom_objects_api.delete_namespaced_custom_object(
                    group="kubernetes.dask.org",
                    version="v1",
                    plural="daskautoscalers",
                    namespace=self.namespace,
                    name=self.name,
                )
            await custom_objects_api.patch_namespaced_custom_object_scale(
                group="kubernetes.dask.org",
                version="v1",
                plural="daskworkergroups",
                namespace=self.namespace,
                name=f"{self.name}-{worker_group}",
                body={"spec": {"replicas": n}},
            )

    def adapt(self, minimum=None, maximum=None):
        """Turn on adaptivity

        Parameters
        ----------
        minimum : int
            Minimum number of workers
        minimum : int
            Maximum number of workers

        Examples
        --------
        >>> cluster.adapt()  # Allow scheduler to add/remove workers within k8s cluster resource limits
        >>> cluster.adapt(minimum=1, maximum=10) # Allow scheduler to add/remove workers within 1-10 range
        """
        return self.sync(self._adapt, minimum, maximum)

    async def _adapt(self, minimum=None, maximum=None):
        async with kubernetes.client.api_client.ApiClient() as api_client:
            custom_objects_api = kubernetes.client.CustomObjectsApi(api_client)
            custom_objects_api.api_client.set_default_header(
                "content-type", "application/merge-patch+json"
            )
            try:
                await custom_objects_api.patch_namespaced_custom_object_scale(
                    group="kubernetes.dask.org",
                    version="v1",
                    plural="daskautoscalers",
                    namespace=self.namespace,
                    name=self.name,
                    body={"spec": {"minimum": minimum, "maximum": maximum}},
                )
            except kubernetes.client.ApiException:
                await custom_objects_api.create_namespaced_custom_object(
                    group="kubernetes.dask.org",
                    version="v1",
                    plural="daskautoscalers",
                    namespace=self.namespace,
                    body={
                        "apiVersion": "kubernetes.dask.org/v1",
                        "kind": "DaskAutoscaler",
                        "metadata": {
                            "name": self.name,
                            "dask.org/cluster-name": self.name,
                            "dask.org/component": "autoscaler",
                        },
                        "spec": {
                            "cluster": self.name,
                            "minimum": minimum,
                            "maximum": maximum,
                        },
                    },
                )

    def __enter__(self):
        return self

    def __exit__(self, typ, value, traceback):
        self.close()

    @classmethod
    def from_name(cls, name, **kwargs):
        """Create an instance of this class to represent an existing cluster by name.

        Will fail if a cluster with that name doesn't already exist.

        Parameters
        ----------
        name: str
            Name of the cluster to connect to

        Examples
        --------
        >>> cluster = KubeCluster.from_name(name="simple-cluster")
        """
        return cls(name=name, create_mode=CreateMode.CONNECT_ONLY, **kwargs)


def make_cluster_spec(
    name,
    image="ghcr.io/dask/dask:latest",
    n_workers=None,
    resources=None,
    env=None,
    worker_command="dask-worker",
    scheduler_service_type="ClusterIP",
):
    """Generate a ``DaskCluster`` kubernetes resource.

    Populate a template with some common options to generate a ``DaskCluster`` kubernetes resource.

    Parameters
    ----------
    name: str
        Name of the cluster
    image: str (optional)
        Container image to use for the scheduler and workers
    n_workers: int (optional)
        Number of workers in the default worker group
    resources: dict (optional)
        Resource limits to set on scheduler and workers
    env: dict (optional)
        Environment variables to set on scheduler and workers
    worker_command: str (optional)
        Worker command to use when starting the workers
    """
    return {
        "apiVersion": "kubernetes.dask.org/v1",
        "kind": "DaskCluster",
        "metadata": {"name": name},
        "spec": {
            "worker": make_worker_spec(
                env=env,
                resources=resources,
                worker_command=worker_command,
                n_workers=n_workers,
                image=image,
            ),
            "scheduler": make_scheduler_spec(
                cluster_name=name,
                env=env,
                resources=resources,
                image=image,
                scheduler_service_type=scheduler_service_type,
            ),
        },
    }


def make_worker_spec(
    image="ghcr.io/dask/dask:latest",
    n_workers=3,
    resources=None,
    env=None,
    worker_command="dask-worker",
):
    if isinstance(env, dict):
        env = [{"name": key, "value": value} for key, value in env.items()]
    else:
        # If they gave us a list, assume its a list of dicts and already ready to go
        env = env

    if isinstance(worker_command, str):
        worker_command = worker_command.split(" ")

    args = worker_command + [
        "--name",
        "$(DASK_WORKER_NAME)",
        "--dashboard",
        "--dashboard-address",
        "8788",
    ]

    return {
        "replicas": n_workers,
        "spec": {
            "containers": [
                {
                    "name": "worker",
                    "image": image,
                    "args": args,
                    "env": env,
                    "resources": resources,
                    "ports": [
                        {
                            "name": "http-dashboard",
                            "containerPort": 8788,
                            "protocol": "TCP",
                        },
                    ],
                }
            ]
        },
    }


def make_scheduler_spec(
    cluster_name,
    env=None,
    resources=None,
    image="ghcr.io/dask/dask:latest",
    scheduler_service_type="ClusterIP",
):
    # TODO: Take the values provided in the current class constructor
    # and build a DaskWorker compatible dict
    if isinstance(env, dict):
        env = [{"name": key, "value": value} for key, value in env.items()]
    else:
        # If they gave us a list, assume its a list of dicts and already ready to go
        env = env

    return {
        "spec": {
            "containers": [
                {
                    "name": "scheduler",
                    "image": image,
                    "args": ["dask-scheduler", "--host", "0.0.0.0"],
                    "env": env,
                    "resources": resources,
                    "ports": [
                        {
                            "name": "tcp-comm",
                            "containerPort": 8786,
                            "protocol": "TCP",
                        },
                        {
                            "name": "http-dashboard",
                            "containerPort": 8787,
                            "protocol": "TCP",
                        },
                    ],
                    "readinessProbe": {
                        "httpGet": {"port": "http-dashboard", "path": "/health"},
                        "initialDelaySeconds": 0,
                        "periodSeconds": 1,
                        "timeoutSeconds": 300,
                    },
                    "livenessProbe": {
                        "httpGet": {"port": "http-dashboard", "path": "/health"},
                        "initialDelaySeconds": 15,
                        "periodSeconds": 20,
                    },
                }
            ]
        },
        "service": {
            "type": scheduler_service_type,
            "selector": {
                "dask.org/cluster-name": cluster_name,
                "dask.org/component": "scheduler",
            },
            "ports": [
                {
                    "name": "tcp-comm",
                    "protocol": "TCP",
                    "port": 8786,
                    "targetPort": "tcp-comm",
                },
                {
                    "name": "http-dashboard",
                    "protocol": "TCP",
                    "port": 8787,
                    "targetPort": "http-dashboard",
                },
            ],
        },
    }


async def wait_for_service(api, service_name, namespace):
    """Block until service is available."""
    while True:
        try:
            service = await api.read_namespaced_service(service_name, namespace)

            # If the service is of type LoadBalancer, also wait until it's ready.
            if (
                service.spec.type == "LoadBalancer"
                and len(service.status.load_balancer.ingress or []) == 0
            ):
                pass
            else:
                break
        except Exception:
            pass
        finally:
            await asyncio.sleep(0.1)


@atexit.register
def reap_clusters():
    async def _reap_clusters():
        for cluster in list(KubeCluster._instances):
            if cluster.shutdown_on_close and cluster.status != Status.closed:
                await ClusterAuth.load_first(cluster.auth)
                with suppress(TimeoutError):
                    if cluster.asynchronous:
                        await cluster.close(timeout=10)
                    else:
                        cluster.close(timeout=10)

    asyncio.run(_reap_clusters())