Azure Container Apps planned maintenance (preview)
Azure Container Apps is a fully managed service where platform and infrastructure updates are regularly and automatically applied to both components and environments. The Container Apps update system is designed to minimize the effect on performance of your apps during updates. By defining maintenance windows, you can designate the most advantageous times for your application.
Defining a maintenance window allows you to decide the range of time when noncritical updates are applied to your Container Apps environment.
The following table describes the difference between the timing in how critical and noncritical updates are applied to your environment.
| Update type | Description | Timing |
|---|---|---|
| Critical | Urgent fixes that include updates essential to the security and stability of your app. | Anytime |
| Noncritical | Routine security patches, bug fixes, and the introduction of new features. | If a planned maintenance window is defined, then updates only start during that time span. If a maintenance window isn't configured, then updates can be applied at any time. |
How maintenance windows work
To control the timing for noncritical updates, you can define a weekly time range for when updates are applied to your environment. When you define a maintenance window, you specify a day of the week, a start time in the UTC format, and a duration.
Keep in mind the following considerations:
You can only have one maintenance window per environment.
The minimum duration for a maintenance window is 8 hours.
Planned maintenance is an optional, best-effort feature that is ideal for environments with interdependent applications seeking added resiliency. When there are critical updates, Container Apps can apply these updates outside of the maintenance window to ensure the security and reliability of the platform and your applications.
Support for maintenance windows is supported in all container apps and jobs, except when they run on consumption workload profiles.
Minimize impact to your applications
In many cases, you can minimize the impact of platform updates on your applications by following these practices:
Timing: Create a maintenance window that aligns with your organization's off-peak hours.
Design: To minimize downtime, follow the guidance for building reliable Container Apps, including the use of availability zones and multiple replicas.
Data management: Configure your apps and jobs to be stateless so that they restart without data loss.
Reliability: When building microservice applications, use the Retry and Circuit Breaker patterns to handle transient failures.
Add a window
You can add a maintenance window to an environment with the maintenance-config add command.
Before running this command, make sure to replace the placeholders surrounded by <> with your own values.
az containerapp env maintenance-config add \
--resource-group <RESOURCE_GROUP> \
--environment <ENVIRONMENT_NAME> \
--weekday Monday \
--start-hour-utc 1 \
--duration 8
Times in UTC format are expressed using the 24-hour time format. For instance, if you want your start hour to be 1:00 pm, then the start-hour-utc value is 13.
Update a window
You can update the maintenance window for an environment with the maintenance-config update command.
Before running this command, make sure to replace the placeholders surrounded by <> with your own values.
az containerapp env maintenance-config update \
--resource-group <RESOURCE_GROUP> \
--environment <ENVIRONMENT_NAME> \
--weekday Monday \
--start-hour-utc 1 \
--duration 9
Times in UTC format are expressed using the 24-hour time format. For instance, if you want your start hour to be 1:00 pm, then the start-hour-utc value is 13.
View the window configuration
You can view an environment's maintenance window with the maintenance-config list command.
az containerapp env maintenance-config list \
--resource-group <RESOURCE_GROUP> \
--environment <ENVIRONMENT_NAME>
Remove a window
To remove an environment's maintenance window, use the maintenance-config remove command.
az containerapp env maintenance-config remove \
--resource-group <RESOURCE_GROUP> \
--environment <ENVIRONMENT_NAME>
View maintenance history
If you have a maintenance window configured, you can see the maintenance actions against your environment within the last 30 days.
Use the following steps to review the maintenance history in the Azure portal.
Open your Container Apps environment in the Azure portal.
Select Diagnose and solve problems.
In the Diagnose and solve problems window, you can view the configured maintenance window and upgrade events that occurred in the last month. As you hover your mouse over the bars in the chart, you can see the start time for each upgrade event.
Considerations
Planned maintenance is free during preview.