Known Issues in the MongoDB Enterprise Kubernetes Operator¶
On this page
- Update Google Firewall Rules to Fix WebHook Issues
- Enable S3 Snapshot Stores in Ops Manager 4.2.10 and 4.2.12
- Configure Persistent Storage Correctly
- Remove Resources before Removing Kubernetes
- Create Separate Namespaces for Kubernetes Operator and MongoDB Resources
- HTTPS Enabled After Deployment
- Difficulties with Updates
- Machine Memory vs. Container Memory
- Changes to Avoid
Update Google Firewall Rules to Fix WebHook Issues¶
When you deploy Kubernetes Operator to GKE private clusters, the MongoDB Kubernetes resources or MongoDBOpsManager resource creation could time out. The following message might appear in the logs:
Error setting state to reconciling: Timeout: request did not complete within requested timeout 30s”.
Google configures its firewalls to restrict access to your Kubernetes pods. To use the webhook service, add a new firewall rule to grant GKE control plane access to your webhook service.
The Kubernetes Operator webhook service runs on port 443.
Enable S3 Snapshot Stores in Ops Manager 4.2.10 and 4.2.12¶
To enable S3 Snapshot stores in Ops Manager 4.2.10 and 4.2.12, you must
set brs.s3.validation.testing: disabled
in
the spec.configuration
property of your Ops Manager
resource specification.
Configure Persistent Storage Correctly¶
If there are no persistent volumes available when you create a resource, the resulting pod stays in transient state and the Operator fails (after 20 retries) with the following error:
To prevent this error, either:
- Provide Persistent Volumes or
- Set
persistent : false
for the resource
For testing only, you may also set persistent : false
. This
must not be used in production, as data is not preserved between
restarts.
Remove Resources before Removing Kubernetes¶
Sometimes Ops Manager can diverge from Kubernetes. This mostly occurs when Kubernetes resources are removed manually. Ops Manager can keep displaying an Automation Agent which has been shut down.
If you want to remove deployments of MongoDB on Kubernetes, use the resource specification to delete resources first so no dead Automation Agents remain.
Create Separate Namespaces for Kubernetes Operator and MongoDB Resources¶
The best strategy is to create Kubernetes Operator and its resources in different namespaces so that the following operations would work correctly:
or
If the Kubernetes Operator and resources sit in the same mongodb
namespace, then operator would also be removed in the same operation.
This would mean that it could not clean the configurations, which
would have to be done in the Ops Manager Application.
HTTPS Enabled After Deployment¶
We recommend that you enable HTTPS before deploying your Ops Manager resources.
However, if you enable HTTPS after deployment,
your managed resources can no longer communicate with Ops Manager and
the Kubernetes Operator reports your resources’ status as Failed
.
To resolve this issue, you must delete your pods by running the following command for each Pod:
After deletion, Kubernetes automatically restarts the deleted Pods. During this period, the resource is unreachable and incurs downtime.
Difficulties with Updates¶
In some cases, the Kubernetes Operator can stop receiving change events. As this problem is hard to reproduce, the recommended workaround is to delete the operator pod. Kubernetes starts the new Kubernetes Operator automatically and starts working correctly:
Machine Memory vs. Container Memory¶
MongoDB versions older than 3.6.13, 4.0.9, and 4.1.9 report host system RAM, not container RAM.
Changes to Avoid¶
The Kubernetes Operator will not be able to apply the following change on a MongoDB Deployment simultaneously:
- The TLS configuration is disabled (
security.tls.enabled: false
) - The number of members in a Replica Set is increased
If both operations are applied at the same time, the MongoDB Resource could go into a unrecoverable state.