Add a k8s cheat sheet to trooper docs

No-Try: true
Docs-Preview: https://skia.org/?cl=190201
Bug: skia:
Change-Id: Idd7d1838a648e1e73d76720dc07bd425ff7929a3
Reviewed-on: https://skia-review.googlesource.com/c/190201
Reviewed-by: Joe Gregorio <jcgregorio@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>

site/dev/sheriffing/trooper.md

@@ -62,3 +62,34 @@ Tips for troopers
 
 - Read over the [Skolo maintenance doc](https://docs.google.com/document/d/1zTR1YtrIFBo-fRWgbUgvJNVJ-s_4_sNjTrHIoX2vulo/edit) for more detail on
   dealing with device alerts.
+
+### Kubernetes cheat sheet ###
+
+Much of the infrastructure runs on Kubernetes (aka k8s). Here are some handy commands:
+
+	# Show possibly problematic pods (i.e. non Running pods)
+	# Look for pods that have been Pending or Terminating a long time
+	kubectl get pods | grep -v Running
+
+	# Get pods by label (or without label)
+	# (see https://skia-review.googlesource.com/c/skia-public-config/+/189960 for
+	# how to implement this on other services)
+	kubectl get pods -lappgroup=perf
+	kubectl get pods -l 'appgroup notin (fiddle)'
+
+	# Get pods grouped by the nodes (i.e. VM) they run on
+	kubectl get pods -o wide --sort-by="{.spec.nodeName}"
+
+	# Get and follow the logs for a pod
+	kubectl logs -f [pod]
+
+	# Get a lot of info for a pod
+	kubectl describe pod [pod]
+
+	# "SSH into" a running pod and poke around (might need /bin/sh instead of bash)
+	kubectl exec -it [pod] /bin/bash
+
+	# delete pods matching a grep e.g. "Terminat"
+	kubectl get pods | grep [search] | awk '{print $1}' | xargs -L 1 kubectl delete pod
+	# delete pods and you really mean it
+	kubectl get pods | grep [search] | awk '{print $1}' | xargs -L 1 kubectl delete pod --force --grace-period=0