Your App Is AliveMichelle Noorali

Developer at Deis@michellenoorali

Helm• Kubernetes Package Manager

• Packages = “Charts”

• “Homebrew” for Kubernetes

• Great way to find, share, and use software built for Kubernetes

• Community focused

• www.helm.sh

Helm ChartsKubernetes manifests + metadata

Try it outgithub.com/helm/charts

Health Checks

What?

a way to monitor your app’s health

A Health Check is

Is your app…responsive?

Is your app…Performant?

Is your app…Stable?

What does it look like?

• /healthcheck or /healthz endpoint

• checked by external system at intervals

• On success, do nothing

• On failure, notify and heal

Health checks continued …

In Kubernetes Land…

• Health checks are built in! • But first…

Introducing Puffy• … a simple go web server

Pre-requisites

• Running Kubernetes cluster on GCE [Google Compute Engine]

• Docker Image for app stored on DockerHub

• DockerHub = place to store images

• Can also use Quay.io or GCR [Google Container Registry]

Puffy Repo

Dockerfile

Makefile

Manifest file

Life of Puffy: It’s Alive• Create a pod definition in manifest

• Create resource in kubernetes from manifest with $ kubectl create -f puffy-pod.yaml

• Watch it come to life with $ kubectl get pods -w

• Talk to a route

• curl pod_ip:port/index on a node

• https://asciinema.org/a/7okfmusa0c368obqxba8t9my4

Let’s make sure puffy is ok.

Here comes the health check part…

Two Probes walk into a coffeeshop…

• Readiness Probe

• Liveness Probe

Wait. What is this probe thing?

• a probe = a diagnostic periodically performed on a container

• Three ways to perform a diagnostic:

• Execute a command in a container

• Successful if exit status code 0

• Perform tcp check on a container’s IP address on a specific port

• Successful if the port is open

• Perform an HTTP Get against the container’s IP address on a specific port

• Successful if response has status code >= 200 and <400

Back to the probes…• Readiness Probe

• Is my app ready to serve traffic?

• On failure, it stops serving requests

• Liveness Probe

• Is my app in a good state?

• On failure, it restarts the pod

Define a Liveness Probe in the Pod Manifest

Apply the Changes in the Pod Manifest to the Cluster

$ kubectl delete -f puffy-pod.yaml

~ edit puffy-pod.yaml ~

$ kubectl create -f pod-puffy.yaml

You’ll see failure

Oops• Forgot to add the /healthz endpoint

• kubectl delete -f puffy-pod.yaml

Add /healthz

• Define /healthz in app (common convention)

• Re-build/re-tag image

• Push image to registry

• Edit image declaration in manifest

Bring Puffy Back!

$ kubectl create -f puffy-pod.yaml or $ helm install puffy

$ kubectl get pods

$ kubectl describe pod puffy

On node, curl ip:port/healthz

Let’s add some complexity.

Puffy on /play

Puffy + Spotify API

ReadinessProbe Definition

/ready

Now we need a redis pod to hang out with

Find a redis chart … to borrow some manifests

and create our own chart

www.github.com/michelleN/helm-charts/many-directions

$ helm repo add michelle https://github.com/michelleN/many-directions$ helm repo list$ helm search many-directions$ helm install many-directions

Things to watch out for

• Try to leave health checks as simple as possible

• Don’t get too aggressive

• Use the right probe for your situation

Summary• Automate monitoring apps with health checks

• Use Kubernetes’s built in health check features

• readinessProbe

• Is your app ready to serve traffic?

• livenessProbe

• Is your app in a good state?

Deployment Manager

+

Coming together to bring you a simple and powerful way to deploy and manage Kubernetes

Charts and is going to CNCF along with the rest of Kubernetes

That’s it folks. Thank you.Puffy: www.github.com/michelleN/puffy Many-directions: www.github.com/michelleN/many-directions My charts: www.github.com/michelleN/charts Helm: www.helm.sh Helm charts: www.github.com/helm/charts

Look for www.github.com/kubernetes/helm

& www.github.com/kubernetes/charts

@michellenoorali