This section outlines new features and enhancements introduced in the Cluster release 5.21.0.

MKE version update from 3.3.12 to 3.3.13

Updated the Mirantis Kubernetes Engine version from 3.3.12 to 3.3.13 for the Container Cloud management, regional, and managed clusters. Also, added support for attachment of existing MKE 3.3.13 clusters.

Network interfaces monitoring

Limited the number of monitored network interfaces to prevent extended Prometheus RAM consumption in big clusters. By default, Prometheus Node Exporter now only collects information of a basic set of interfaces, both host and container. If required you can edit the list of excluded devices as needed.

Custom Prometheus recording rules

Implemented the capability to define custom Prometheus recording rules through the prometheusServer.customRecordingRules parameter in the StackLight Helm chart. Overriding of existing recording rules is not supported.

Syslog packet size configuration

Implemented the capability to configure packet size for the syslog logging output. If remote logging to syslog is enabled in StackLight, use the logging.syslog.packetSize parameter in the StackLight Helm chart to configure the packet size.

Prometheus Relay configuration

Implemented the capability to configure the Prometheus Relay client timeout and response size limit through the prometheusRelay.clientTimeout and prometheusRelay.responseLimitBytes parameters in the StackLight Helm chart.

Ceph networks validation

Implemented additional validation of networks specified in spec.cephClusterSpec.network.publicNet and spec.cephClusterSpec.network.clusterNet and prohibited the use of the CIDR. Now, the bare metal provider automatically translates the network range to the default LCM IPAM subnet if it exists.

You can now also add corresponding labels for the bare metal IPAM subnets when configuring the Ceph cluster during the management cluster deployment.

Enhanced Ceph architecture

To improve debugging and log reading, separated Ceph Controller, Ceph Status Controller, and Ceph Request Controller, which used to run in one pod, into three different deployments.

Automated Ceph OSD removal


Implemented the KaaSCephOperationRequest CR that provides LCM operations for Ceph OSDs and nodes by automatically creating separate CephOsdRemoveRequest requests. It allows for automated removal of healthy or non-healthy Ceph OSDs from a Ceph cluster.

Due to the Technology Preview status of the feature, Mirantis recommends following Remove Ceph OSD manually for Ceph OSDs removal.

Learn more

Remove a Ceph OSD