carvel-dev / ytt-library-for-kubernetes-demo

Demo of ytt + kapp + k8s-lib to deploy a simple app with basic autoscaling

k8s-lib-demo

Deploy nginx ingress with ytt and kapp

$ ytt -f nginx-ingress/ | kapp -y deploy -a nginx-ingress -f -

(Included nginx ingress is not configured for production use, only for demo purposes)

apps

Deploy two apps (see apps/hello1.yml for definition; relies on k8s-lib)

$ ytt -f apps/config | kapp -y deploy -a apps -f -

See that there is only one hello1 Pod

$ kapp inspect -a apps -t

Expose ingress to your machine with kwt

$ sudo -E kwt net start

Check that app successfully responds with configured text

$ curl http://nginx-ingress-controller.default.svc.cluster.local/

Throw some load at the app, and you should see it be autoscaled some time after

$ siege -c 100 http://nginx-ingress-controller.default.svc.cluster.local/

(In my setup, it took several minutes for HPA to scale up/down)

You can also access second app

$ curl http://nginx-ingress-controller.default.svc.cluster.local/ -H "Host: hello2.com"

simple-app (exercises kbld)

Deploy simple Golang app with help of ytt, kbld, and kapp

$ cd simple-app
$ ytt -f . | kbld -f - | kapp -y deploy -a simple-app -f - --diff-changes

kbld requires Docker CLI (docker) available on $PATH as it builds a container based on simple-app/src/ directory. You can grab Docker CLI binaries here.

If you are using minikube you'll have to expose Docker daemon via eval $(minikube docker-env) where kbld will run. Otherwise, you will have to add configuration (below) for pushing images to simple-app/manifest.yml so that built image is available to your Kubernetes cluster. (Don't forget to run docker login so that images can be pushed.)

---
apiVersion: kbld.k14s.io/v1alpha1
kind: ImageDestinations
destinations:
- image: simple-app-image
  newImage: docker.io/dkalinin/simple-app # or whatever push target your Docker can push to

simple-app-k8s-lib/ directory is similar to simple-app/ with an exception that it uses k8s-lib to generate app configuration (use ytt -f config/).

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