Documentation for Debugging Snapshotter

cluster-autoscaler/debuggingsnapshot/README.md

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+# Debugging Snapshotter
+ It's a tool to visualize the internal state of cluster-autoscaler at a point in time to help debug autoscaling issues.
+
+---
+### Requirements
+Require Cluster-autoscaler versions 1.24+
+
+---
+#### What data snapshotter can capture?
+https://github.com/kubernetes/autoscaler/blob/master/cluster-autoscaler/debuggingsnapshot/debugging_snapshot.go#L60C1-L71C1
+```go
+type DebuggingSnapshotImpl struct {
+	NodeList                      []*ClusterNode          `json:"NodeList"`
+	UnscheduledPodsCanBeScheduled []*v1.Pod               `json:"UnscheduledPodsCanBeScheduled"`
+	Error                         string                  `json:"Error,omitempty"`
+	StartTimestamp                time.Time               `json:"StartTimestamp"`
+	EndTimestamp                  time.Time               `json:"EndTimestamp"`
+	TemplateNodes                 map[string]*ClusterNode `json:"TemplateNodes"`
+}
+
+```
+
+#### Development
+1. First step is enable the snapshotter adding the following flag to cluster-autoscaler [manifest](https://github.com/kubernetes/autoscaler/blob/master/cluster-autoscaler/cloudprovider/bizflycloud/manifest/cluster-autoscaler.yaml) .
+
+```
+--debugging-snapshot-enabled=true
+```
+2. Save the updated manifest file and apply it to your Kubernetes cluster using:
+
+```bash
+kubectl apply -f <path-to-your-manifest-file>
+```
+3. once you deploy your pod make a snap shot request
+```sh
+ curl http://127.0.0.1:8085/snapshotz > FIlE_NAME.json
+```
+
+#### How to nevigate JSON file?
+
+```sh
+cat tmp.json | jq 'keys'
+cat tmp.json | jq '.NodeList | keys' //to see how many nodes are running
+cat tmp.json | jq '.TempletsNodes | keys' //to see templated nodes
+cat tmp.json | jq '.UnscheduledPodsCanBeScheduled | keys' //to see unscheduled pods that can be scheduled
+```