<p>I've a GCP GKE cluster with version '1.22.12-gke.300'. There are around 20 nodes distributed in 4 node pools. The cluster was created a month before and last day I noticed that all of my nodes are rebooted/restarted. When I see the details of the node using command <code>kubectl get nodes</code>, I'm seeing this result (below). The age of all the nodes are 16 or 17 hours.</p>
<pre><code>gke-company-name-gke-clust-company-name-default-n-97c8e50a-d63m   Ready    &lt;none&gt;   17h     v1.22.12-gke.300
gke-company-name-gke-clust-company-name-default-n-97c8e50a-l8zw   Ready    &lt;none&gt;   17h     v1.22.12-gke.300
gke-company-name-gke-clust-company-name-demo-app--d251216f-2uou   Ready    &lt;none&gt;   16h     v1.22.12-gke.300
gke-company-name-gke-clust-company-name-demo-app--d251216f-3mj1   Ready    &lt;none&gt;   16h     v1.22.12-gke.300
gke-company-name-gke-clust-company-name-demo-app--d251216f-doml   Ready    &lt;none&gt;   16h     v1.22.12-gke.300
gke-company-name-gke-clust-company-name-prod-app--5ae07853-7mwd   Ready    &lt;none&gt;   17h     v1.22.12-gke.300
gke-company-name-gke-clust-company-name-prod-app--5ae07853-gzxy   Ready    &lt;none&gt;   17h     v1.22.12-gke.300
gke-company-name-gke-clust-company-name-prod-app--5ae07853-lgvo   Ready    &lt;none&gt;   17h     v1.22.12-gke.300
gke-company-name-gke-clust-company-name-prod-nifi-fd3e5533-27gf   Ready    &lt;none&gt;   16h     v1.22.12-gke.300
gke-company-name-gke-clust-company-name-prod-nifi-fd3e5533-7r4q   Ready    &lt;none&gt;   16h     v1.22.12-gke.300
gke-company-name-gke-clust-company-name-prod-nifi-fd3e5533-e680   Ready    &lt;none&gt;   16h     v1.22.12-gke.300
gke-company-name-gke-clust-company-name-prod-nifi-fd3e5533-m2vf   Ready    &lt;none&gt;   17h     v1.22.12-gke.300
gke-company-name-gke-clust-company-name-prod-nifi-fd3e5533-mtvg   Ready    &lt;none&gt;   17h     v1.22.12-gke.300
gke-company-name-gke-clust-company-name-prod-nifi-fd3e5533-mwiy   Ready    &lt;none&gt;   16h     v1.22.12-gke.300
gke-company-name-gke-clust-company-name-prod-nifi-fd3e5533-rwf9   Ready    &lt;none&gt;   16h     v1.22.12-gke.300
gke-company-name-gke-clust-company-name-prod-nifi-fd3e5533-tqe0   Ready    &lt;none&gt;   17h     v1.22.12-gke.300
gke-company-name-gke-clust-company-name-prod-nifi-fd3e5533-weai   Ready    &lt;none&gt;   17h     v1.22.12-gke.300
gke-company-name-gke-clust-company-name-prod-nifi-fd3e5533-xmss   Ready    &lt;none&gt;   16h     v1.22.12-gke.300
</code></pre>
<p>Is there any way to identify the reason behing this reboot/restart. Because this unexpected reboot caused some issues to my system. I just wanted to identify the reason of these reboots so that I can know that these types of reboots are expected in future.</p>
<p>Any help is appreciated.</p>

<p>I received the answer to my question on this <a href="https://serverfault.com/questions/1078073/find-out-why-a-kubernetes-cluster-was-restarted-on-google-cloud">link</a> from the above comment.  I'll just explain the scenario for others to benefit.</p>
<p>I created a cluster on GKE with the Release channels as &quot;Regular&quot;. Because of choosing that, GKE will automatically upgrade the cluster and nodes whenever a new security or patch update got released.</p>
<p>You can find the upgrade status by using this command</p>
<pre><code>gcloud container operations list --filter=&quot;TYPE:UPGRADE_MASTER&quot;
</code></pre>
