Known issues¶
MKE 3.6.1 known issues with available workaround solutions include:
[MKE-9358] cgroup v2 (unsupported) is enabled in RHEL 9.0 by default
[MKE-10017] ucp-pause containers use incorrect version after upgrade rollback
[MKE-8914] Windows Server Core with Containers images incompatible with GCP
[MKE-8814] Mismatched MTU values cause Swarm overlay network issues on GCP
[MKE-9358] cgroup v2 (unsupported) is enabled in RHEL 9.0 by default¶
As MKE does not support cgroup v2 on Linux platforms, RHEL 9.0 users will be unable to use the software due to cgroup v2 default enablement.
As a workaround, RHEL 9.0 users must disable cgroup v2.
[MKE-10017] ucp-pause containers use incorrect version after upgrade rollback¶
After rolling back to MKE 3.6.1 during an upgrade to any later version, some
MKE nodes may run ucp-pause
containers built from the upgraded version of
the MKE images.
Workaround:
Perform the following steps on each Linux node where the ucp-pause
containers are built from the upgraded MKE image version.
Verify that the
ucp-pause
containers are using the MKE image version to which you tried to upgrade:docker ps -a | grep ucp-pause
Example output:
01a80dd175de mirantiseng/ucp-pause:3.7.0 "/pause" 17 minutes ago Up 16 minutes k8s_POD_ucp-node-feature-discovery-9bwsj_node-feature-discovery_0a601160-ecf7-412f-bff8-e421a4f1712d_0 498371f35994 mirantiseng/ucp-pause:3.7.0 "/pause" 20 minutes ago Up 18 minutes k8s_POD_coredns-7fb76597fc-k2q2k_kube-system_83fee771-dc1d-4e34-ae45-f0ab9dee5942_0 a94cfcfb18f6 mirantiseng/ucp-pause:3.7.0 "/pause" 22 minutes ago Up 21 minutes k8s_POD_calico-kube-controllers-58c64b9976-mg5dn_kube-system_0b80ed92-be02-40de-827e-6a6b6e7f27da_0 0a2cf203f77c mirantiseng/ucp-pause:3.7.0 "/pause" 22 minutes ago Up 21 minutes k8s_POD_calico-node-f2xhl_kube-system_3c4a27c5-b832-417d-bc30-b6a7ca8f7627_0
If the
ucp-pause
containers are using the correct image version, proceed to the next node.Copy the
cri-dockerd-mke.service
configuration file from thetmp
directory to/usr/lib/systemd/system
:sudo cp /tmp/cri-dockerd-mke.service /usr/lib/systemd/system
Restart kubelet to load the most recent configuration file:
docker rm -f ucp-kubelet
Delete all
ucp-pause
containers that are on the node:docker rm -f <pause-containrer-id-1> <pause-containrer-id-n>
Verify that the
ucp-pause
containers are using the correct MKE image version:docker ps -a | grep ucp-pause
Example output:
236b3dfb1bf6 mirantiseng/ucp-pause:3.6.4 "/pause" 12 seconds ago Up 11 seconds k8s_POD_calico-node-dp7hd_kube-system_d59d9004-5a59-46f8-8281-3c917c62fe20_0 56994306b181 mirantiseng/ucp-pause:3.6.4 "/pause" 12 seconds ago Up 11 seconds k8s_POD_calico-kube-controllers-64844db68f-br9dh_kube-system_5ea39708-231a-45f5-aa7c-f7b842131941_0 e62ae3c2a871 mirantiseng/ucp-pause:3.6.4 "/pause" 12 seconds ago Up 11 seconds k8s_POD_ucp-node-feature-discovery-rdrb7_node-feature-discovery_848cda05-74ec-4db2-825f-05afa53b2502_0 d51eba420f34 mirantiseng/ucp-pause:3.6.4 "/pause" 12 seconds ago Up 11 seconds k8s_POD_coredns-78c7f4f4c7-lljzc_kube-system_92936b7c-6a7c-4eb5-a83f-22514acac636_0
[MKE-8914] Windows Server Core with Containers images incompatible with GCP¶
The use of Windows ServerCore with Containers images will prevent kubelet
from starting up, as these images are not compatible with GCP.
As a workaround, use Windows Server or Windows Server Core images.
[MKE-8814] Mismatched MTU values cause Swarm overlay network issues on GCP¶
Communication between GCP VPCs and Docker networks that use Swarm overlay networks will fail if their MTU values are not manually aligned. By default, the MTU value for GCP VPCs is 1460, while the default MTU value for Docker networks is 1500.
Workaround:
Select from the following options:
Create a new VPC and set the MTU value to 1500.
Set the MTU value of the existing VPC to 1500.
For more information, refer to the Google Cloud Platform documentation, Change the MTU setting of a VPC network.