While you are reading this we are starting a simple single node Kubernetes cluster for you. Please be patient and wait until the launch.sh script has finished.
Now let's create a simple Deployment which defines a liveness and readiness probe. The application itself is a simple REST service which just returns a freshly generated random number each time it is called.
In deployment.yml you find the definition for this Deployment.
Check the content of this declaration with
bat deployment.yml{{execute}}
Please look specifically at the livenessProbe and readinessProbe declaration which do a HTTP based and file based health check, respectively.
Now it's time to create that Pod with
kubectl create -f deployment.yml{{execute}}
and watch how it starts up the application pods:
kubectl get pods -w{{execute}}
(you can stop this with CTRL-C).
When the pod is up and running (status is 1/1 Running), let's create a Service to access the application.
We are using here a NodePort service with our application listening on a fixed port on every node of our cluster:
kubectl create -f service.yml{{execute interrupt}}
The random number service can now be accessed in Katacoda with
curl -s http://[[HOST_IP]]:31667/ | jq .{{execute}}
or you can also reach it externally via http://[[HOST_SUBDOMAIN]]-31667-[[KATACODA_HOST]].environments.katacoda.com/
To access the health check which is used in the liveness probe, try
curl -s http://[[HOST_IP]]:31667/actuator/health | jq .{{execute}}