Use Planned Maintenance to schedule and control upgrades for your Azure Kubernetes Service (AKS) cluster
This article shows you how to use Planned Maintenance to schedule and control cluster and node image upgrades in Azure Kubernetes Service (AKS).
Your AKS cluster has regular maintenance performed on it automatically. There are two types of maintenance operations: AKS-initiated and user-initiated. AKS-initiated maintenance involves the weekly releases that AKS performs to keep your cluster up-to-date with the latest features and fixes. User-initiated maintenance includes cluster auto-upgrades and Node OS automatic security updates. The Planned Maintenance feature allows you to run both types of maintenance in a cadence of your choice, thereby minimizing any workload impact.
Before you begin
- This article assumes that you have an existing AKS cluster. If you don't have an AKS cluster, see Create an AKS cluster.
- If using the Azure CLI, make sure you upgrade to the latest version using the
az upgrade
command.
Considerations
When you use Planned Maintenance, the following considerations apply:
- AKS reserves the right to break Planned Maintenance windows for unplanned, reactive maintenance operations that are urgent or critical. These maintenance operations might even run during the
notAllowedTime
ornotAllowedDates
periods defined in your configuration. - Performing maintenance operations are considered best-effort only and aren't guaranteed to occur within a specified window.
Planned Maintenance schedule configurations
There are three available maintenance schedule configuration types: default
, aksManagedAutoUpgradeSchedule
, and aksManagedNodeOSUpgradeSchedule
.
default
is a basic configuration used to control AKS releases. The releases can take up to two weeks to roll out to all regions from the initial time of shipping due to Azure Safe Deployment Practices (SDP). Choosedefault
to schedule these updates in a manner that's least disruptive for you. You can monitor the status of an ongoing AKS release by region with the weekly releases tracker.aksManagedAutoUpgradeSchedule
controls when to perform cluster upgrades scheduled by your designated auto-upgrade channel. You can configure more finely-controlled cadence and recurrence settings with this configuration compared to thedefault
configuration. For more information on cluster auto-upgrade, see Automatically upgrade an Azure Kubernetes Service (AKS) cluster.aksManagedNodeOSUpgradeSchedule
controls when to perform the node operating system (OS) security patching scheduled by your node OS auto-upgrade channel. You can configure more finely-controlled cadence and recurrence settings with this configuration compared to thedefault
configuration. For more information on node OS auto-upgrade channel, see Automatically patch and update AKS cluster node images
We recommend using aksManagedAutoUpgradeSchedule
for all cluster upgrade scenarios and aksManagedNodeOSUpgradeSchedule
for all node OS security patching scenarios. The default
option is meant exclusively for AKS weekly releases. You can switch the default
configuration to the aksManagedAutoUpgradeSchedule
or aksManagedNodeOSUpgradeSchedule
configurations using the az aks maintenanceconfiguration update
command.
Creating a maintenance window
Note
When using auto-upgrade, to ensure proper functionality, use a maintenance window with a duration of four hours or more.
Planned Maintenance windows are specified in Coordinated Universal Time (UTC).
A default
maintenance window has the following properties:
Name | Description | Default value |
---|---|---|
timeInWeek |
In a default configuration, this property contains the day and hourSlots values defining a maintenance window |
N/A |
timeInWeek.day |
The day of the week to perform maintenance in a default configuration |
N/A |
timeInWeek.hourSlots |
A list of hour-long time slots to perform maintenance on a given day in a default configuration |
N/A |
notAllowedTime |
Specifies a range of dates that maintenance can't run, determined by start and end child properties. Only applicable when creating the maintenance window using a config file |
N/A |
An aksManagedAutoUpgradeSchedule
or aksManagedNodeOSUpgradeSchedule
maintenance window has the following properties:
Name | Description | Default value |
---|---|---|
utcOffset |
Used to determine the timezone for cluster maintenance | +00:00 |
startDate |
The date on which the maintenance window begins to take effect | The current date at creation time |
startTime |
The time for maintenance to begin, based on the timezone determined by utcOffset |
N/A |
schedule |
Used to determine frequency. Three types are available: Weekly , AbsoluteMonthly , and RelativeMonthly |
N/A |
intervalDays |
The interval in days for maintenance runs. Only applicable to aksManagedNodeOSUpgradeSchedule |
N/A |
intervalWeeks |
The interval in weeks for maintenance runs | N/A |
intervalMonths |
The interval in months for maintenance runs | N/A |
dayOfWeek |
The specified day of the week for maintenance to begin | N/A |
durationHours |
The duration of the window for maintenance to run | N/A |
notAllowedDates |
Specifies a range of dates that maintenance cannot run, determined by start and end child properties. Only applicable when creating the maintenance window using a config file |
N/A |
Understanding schedule types
There are four available schedule types: Daily
, Weekly
, AbsoluteMonthly
, and RelativeMonthly
. These schedule types are only applicable to aksManagedClusterAutoUpgradeSchedule
and aksManagedNodeOSUpgradeSchedule
configurations. Daily
schedules are only applicable to aksManagedNodeOSUpgradeSchedule
types.
Note
All of the fields shown for each respective schedule type are required.
Daily schedule
Note
Daily schedules are only applicable to aksManagedNodeOSUpgradeSchedule
configuration types.
A Daily
schedule may look like "every three days":
"schedule": {
"daily": {
"intervalDays": 3
}
}
Weekly schedule
A Weekly
schedule may look like "every two weeks on Friday":
"schedule": {
"weekly": {
"intervalWeeks": 2,
"dayOfWeek": "Friday"
}
}
AbsoluteMonthly schedule
An AbsoluteMonthly
schedule may look like "every three months, on the first day of the month":
"schedule": {
"absoluteMonthly": {
"intervalMonths": 3,
"dayOfMonth": 1
}
}
RelativeMonthly schedule
A RelativeMonthly
schedule may look like "every two months, on the last Monday":
"schedule": {
"relativeMonthly": {
"intervalMonths": 2,
"dayOfWeek": "Monday",
"weekIndex": "Last"
}
}
Valid values for weekIndex
include First
, Second
, Third
, Fourth
, and Last
.
Add a maintenance window configuration
Add a maintenance window configuration to an AKS cluster using the
az aks maintenanceconfiguration add
command.The first example adds a new
default
configuration that schedules maintenance to run from 1:00am to 2:00am every Monday. The second example adds a newaksManagedAutoUpgradeSchedule
configuration that schedules maintenance to run every third Friday between 12:00 AM and 8:00 AM in theUTC+5:30
timezone.# Add a new default configuration az aks maintenanceconfiguration add --resource-group myResourceGroup --cluster-name myAKSCluster --name default --weekday Monday --start-hour 1 # Add a new aksManagedAutoUpgradeSchedule configuration az aks maintenanceconfiguration add --resource-group myResourceGroup --cluster-name myAKSCluster --name aksManagedAutoUpgradeSchedule --schedule-type Weekly --day-of-week Friday --interval-weeks 3 --duration 8 --utc-offset +05:30 --start-time 00:00
Note
When using a
default
configuration type, you can omit the--start-time
parameter to allow maintenance anytime during a day.
Update an existing maintenance window
Update an existing maintenance configuration using the
az aks maintenanceconfiguration update
command.The following example updates the
default
configuration to schedule maintenance to run from 2:00am to 3:00am every Monday.az aks maintenanceconfiguration update --resource-group myResourceGroup --cluster-name myAKSCluster --name default --weekday Monday --start-hour 2
List all maintenance windows in an existing cluster
List the current maintenance configuration windows in your AKS cluster using the az aks maintenanceconfiguration list
command.
az aks maintenanceconfiguration list --resource-group myResourceGroup --cluster-name myAKSCluster
Show a specific maintenance configuration window in an existing cluster
View a specific maintenance configuration window in your AKS cluster using the az aks maintenanceconfiguration show
command with the --name
parameter.
az aks maintenanceconfiguration show --resource-group myResourceGroup --cluster-name myAKSCluster --name aksManagedAutoUpgradeSchedule
The following example output shows the maintenance window for aksManagedAutoUpgradeSchedule:
{
"id": "/subscriptions/<subscription>/resourceGroups/myResourceGroup/providers/Microsoft.ContainerService/managedClusters/myAKSCluster/maintenanceConfigurations/aksManagedAutoUpgradeSchedule",
"maintenanceWindow": {
"durationHours": 4,
"notAllowedDates": [
{
"end": "2024-01-05",
"start": "2023-12-23"
}
],
"schedule": {
"absoluteMonthly": {
"dayOfMonth": 1,
"intervalMonths": 3
},
"daily": null,
"relativeMonthly": null,
"weekly": null
},
"startDate": "2023-01-20",
"startTime": "09:00",
"utcOffset": "-08:00"
},
"name": "aksManagedAutoUpgradeSchedule",
"notAllowedTime": null,
"resourceGroup": "myResourceGroup",
"systemData": null,
"timeInWeek": null,
"type": null
}
Delete a maintenance configuration window in an existing cluster
Delete a maintenance configuration window in your AKS cluster using the
az aks maintenanceconfiguration delete
command.The following example deletes the
autoUpgradeSchedule
maintenance configuration.az aks maintenanceconfiguration delete --resource-group myResourceGroup --cluster-name myAKSCluster --name autoUpgradeSchedule
FAQ
How can I check the existing maintenance configurations in my cluster?
Use the
az aks maintenanceconfiguration show
command.Can reactive, unplanned maintenance happen during the
notAllowedTime
ornotAllowedDates
periods too?Yes, AKS reserves the right to break these windows for unplanned, reactive maintenance operations that are urgent or critical.
How can you tell if a maintenance event occurred?
For releases, check your cluster's region and look up release information in weekly releases and validate if it matches your maintenance schedule or not. To view the status of your auto upgrades, look up activity logs on your cluster. You may also look up specific upgrade related events as mentioned in Upgrade an AKS cluster. AKS also emits upgrade related Event Grid events. To learn more, see AKS as an Event Grid source.
Can you use more than one maintenance configuration at the same time?
Yes, you can run all three configurations i.e
default
,aksManagedAutoUpgradeSchedule
,aksManagedNodeOSUpgradeSchedule
simultaneously. In case the windows overlap AKS decides the running order.I configured a maintenance window, but upgrade didn't happen - why?
AKS auto-upgrade needs a certain amount of time to take the maintenance window into consideration. We recommend at least 24 hours between the creation or update of a maintenance configuration the scheduled start time.
Also, ensure your cluster is started when the planned maintenance window is starting. If the cluster is stopped, then its control plane is deallocated and no operations can be performed.
AKS auto-upgrade didn't upgrade all my agent pools - or one of the pools was upgraded outside of the maintenance window?
If an agent pool fails to upgrade (for example, because of Pod Disruption Budgets preventing it to upgrade) or is in a Failed state, then it might be upgraded later outside of the maintenance window. This scenario is called "catch-up upgrade" and avoids letting Agent pools with a different version than the AKS control plane.
Are there any best practices for the maintenance configurations?
We recommend setting the Node OS security updates schedule to a weekly cadence if you're using
NodeImage
channel since a new node image gets shipped every week and daily if you opt in forSecurityPatch
channel to receive daily security updates. Set the auto-upgrade schedule to a monthly cadence to stay on top of the kubernetes N-2 support policy. For a detailed discussion of upgrade best practices and other considerations, see AKS patch and upgrade guidance.
Next steps
- To get started with upgrading your AKS cluster, see Upgrade an AKS cluster
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