Add how to debug Memgraph under k8s

pages/database-management/debugging.mdx

@@ -250,3 +250,133 @@ hotspot perf.data
 you should be able to see a similar flamegraph like in the picture below.
 
 ![](/pages/database-management/debugging/perf.png)
+
+## Debugging Memgraph under Kubernetes (k8s)
+
+### General Commands
+
+Managing [nodes](https://kubernetes.io/docs/concepts/architecture/nodes/):
+```
+kubectl get nodes --show-labels # Show all nodes and their labels.
+kubectl top nodes               # Get the current memory usage.
+```
+
+Managing [pods](https://kubernetes.io/docs/concepts/workloads/pods/):
+```
+kubectl get pods --show-labels               # Show all pods and their labels.
+kubectl get pods -o wide                     # Inspect how pods get scheduled.
+kubectl describe pod <pod-name>              # Inspect pod config (args, envs, ...).
+kubectl exec -it <pod-name> -- /bin/bash     # Login to a runnning pod.
+kubectl logs <pod-name>                      # Get logs for a running pod.
+kubectl logs memgraph-data-0-0 | tail -n 100 # Filter last logs from a running pod.
+kubectl logs --previous <pod-name>           # Get logs from a crashed pod.
+kubectl cp <pod-name>:<pod-path> .           # Copy logs from a running pod.
+```
+
+[Events](https://kubernetes.io/docs/reference/kubernetes-api/cluster-resources/event-v1/):
+```
+kubectl get events --all-namespaces  --sort-by='.metadata.creationTimestamp' # List all events by creation time.
+kubectl get events --namespace <namespace-name>                              # List all events in the given namespace.
+```
+
+[StatefulSets](https://kubernetes.io/docs/tutorials/stateful-application/basic-stateful-set/):
+```
+kubectl get statefulsets                  # Show all StatefulSets.
+kubectl get pvc -l app=<statefulset-name> # Get the PersistentVolumeClaims for the StatefulSet.
+```
+
+### Debugging Running Pods
+
+### Creating the Debugging Memgraph Pod
+
+The main issue with debugging under k8s (running gdb) is that the container
+needs to be in the privileged mode. To run any given container in the
+privileged mode, the k8s cluster itself needs to have an appropriate
+configuration.
+
+Below is an example on how to start the privileged `kind` cluster. First create
+a new config `debug-cluster.yaml` file:
+```
+kind: Cluster
+apiVersion: kind.x-k8s.io/v1alpha4
+nodes:
+  - role: control-plane
+    image: kindest/node:v1.31.0
+    extraPortMappings:
+      - containerPort: 80
+        hostPort: 8080
+        protocol: TCP
+    kubeadmConfigPatches:
+      - |
+        kind: ClusterConfiguration
+        kubeletConfiguration:
+          extraArgs:
+            allow-privileged: "true"
+# To inspect the cluster run `kubectl get pods -n kube-system`.
+# If some of the pods is in the CrashLoopBackOff status, try runnig `kubectl
+# logs <pod-name> -n kube-system` to get the error message.
+```
+To start the cluster, you have to execute:
+```
+kind create cluster --name <cluster-name> --config debug-cluster.yaml
+```
+
+Once cluster is up and running, create a new `debug-pod.yaml` file with the
+following content:
+```
+apiVersion: v1
+kind: Pod
+metadata:
+  name: debug-pod
+spec:
+  containers:
+  - name: my-container
+    image: memgraph/memgraph:3.2.0-relwithdebinfo # Use the latest, but make sure it's the relwithdebinfo one!
+    securityContext:
+      runAsUser: 0  # Runs the container as root.
+      privileged: true
+      capabilities:
+        add: ["SYS_PTRACE"]
+      allowPrivilegeEscalation: true
+    command: ["sleep"]
+    args: ["infinity"]
+    stdin: true
+    tty: true
+```
+
+To get the pod up and running and open a shell inside it run:
+```
+kubectl apply -f debug-pod.yaml
+kubectl exec -it debug-pod -- bash
+```
+
+Once you are in the pod execute:
+```
+apt-get update && apt-get install -y gdb
+su memgraph
+gdb --args ./memgraph <memgraph-flags>
+run
+```
+
+Once you have memgraph up and running under `gdb`, run your workload (insert
+data, write or queries…). When you manage to recreate the issue, use the [gdb
+commands](/database-management/debugging#list-of-useful-commands-when-in-gdb)
+to pin point the exact issue.
+
+To delete the debug pod run:
+```
+kubectl delete pod debug-pod
+```
+
+k8s official documentation on how to [debug running
+pods](https://kubernetes.io/docs/tasks/debug/debug-application/debug-running-pod/)
+is quite detailed.
+
+### Specific Cloud Provider Instructions
+
+* [AWS](https://github.com/memgraph/helm-charts/tree/main/charts/memgraph-high-availability/aws)
+* [Azure](https://github.com/memgraph/helm-charts/blob/main/charts/memgraph-high-availability/aks)
+
+The [k8s quick
+reference](https://kubernetes.io/docs/reference/kubectl/quick-reference/) is an
+amazing set of commands!