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[Docs] improve OffloadingBackOff warning message and documentation #2975

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Mar 5, 2025
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[Docs] improve OffloadingBackOff warning message and documentation #2975

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17 changes: 12 additions & 5 deletions docs/faq/faq.md
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Original file line number Diff line number Diff line change
Expand Up @@ -34,9 +34,14 @@ You can find additional information [here](https://github.com/liqotech/liqo/issu

### Why DaemonSets pods (e.g., Kube-Proxy, CNI pods) scheduled on virtual nodes are in OffloadingBackOff?

The majority of DaemonsSets pods (e.g., Kube-Proxy, CNI pods) that are scheduled on Liqo virtual nodes will result in the **OffloadingBackOff** state.
This generally does not represent a problem.
It is recommended to prevent the scheduling of a DaemonSet pod on a virtual node if needed, using the following *NodeAffinity*:
The virtual nodes generated by Liqo have a [taint](https://kubernetes.io/docs/concepts/scheduling-eviction/taint-and-toleration/) that prevents pods from being scheduled on a virtual node (so on the remote cluster) unless the pod is a created in an [offloaded namespace](../usage/namespace-offloading.md).

However, the majority of DaemonsSets (e.g., Kube-Proxy, CNI pods) have pretty wide tolerations to make sure that their pods are created in each node of the cluster.
As a result, a pod is forced to be scheduled on a Liqo virtual node, which rejects it and puts the pod in the **OffloadingBackOff** state.
While this is generally not an issue, during upgrades of those applications, the pod in the **OffloadingBackOff** state might be interpreted as an upgrade failure.

A strategy to prevent the scheduling of a DaemonSet pod on Liqo virtual nodes is using *NodeAffinity*.
For example, you might add the following under the `.spec.template.spec.affinity` field of your DaemonSet:

```yaml
nodeAffinity:
Expand All @@ -47,6 +52,8 @@ nodeAffinity:
operator: DoesNotExist
```

This ensures that a pod is **not** created on any nodes with the `liqo.io/type` label.

(FAQInstallationSection)=

## Installation
Expand Down Expand Up @@ -87,8 +94,8 @@ At this point, you should be able to delete the ForeignCluster.
If there are no peerings left you can uninstall Liqo if needed.

```{warning}
This is a not recommended solution, use this only as a last resort if no other viable options are possible.
Future upgrades will make it easier to unpeer a cluster or uninstall Liqo.
This is a not recommended solution, use this only as a last resort if no other viable options are possible.
Future upgrades will make it easier to unpeer a cluster or uninstall Liqo.
```

(FAQPeerOverIngress)=
Expand Down
10 changes: 9 additions & 1 deletion pkg/virtualKubelet/forge/events.go
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Expand Up @@ -18,6 +18,7 @@ import (
"fmt"

offloadingv1beta1 "github.com/liqotech/liqo/apis/offloading/v1beta1"
"github.com/liqotech/liqo/pkg/consts"
)

const (
Expand Down Expand Up @@ -78,7 +79,14 @@ func EventFailedDeletionMsg(err error) string {

// EventReflectionDisabledMsg returns the message for the event when reflection is disabled for the given namespace.
func EventReflectionDisabledMsg(namespace string) string {
return fmt.Sprintf("Reflection to cluster %q disabled for namespace %q", RemoteCluster, namespace)
return fmt.Sprintf("Reflection to cluster %q disabled for namespace %q. "+
"If this is a DaemonSet scheduling pods in all the nodes across the cluster, "+
"you might want to prevent scheduling on Liqo Virtual Nodes. "+
"You can configure the rules under `spec.template.spec.affinity.nodeAffinity` so that the pods "+
"are not scheduled on Nodes having the label %s=%s. "+
"For further info check the documentation.",
RemoteCluster, namespace, consts.TypeLabel, consts.TypeNode,
)
}

// EventReflectionDisabledErrorMsg returns the message for the event when reflection is disabled for the given namespace, and an error occurs.
Expand Down
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