Ticketing

Stack: Javascript, Typescript, Node, Express, Next, React

Env: Docker, Kubernetes, Skaffold

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A Microservices app-template with NATS Streaming Server for a fully functional community ticket sales app. including

• native auth
• an SSR frontend with Next and React
• CRUD tickets
• CRUD orders
• manage payments with Stripe
• CI/CD

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A bit of Setup

Add ticketing.dev path to localhost

code /etc/hosts

add to the end of the file

127.0.0.1 ticketing.dev

Create a secret keys for use as a local env variable in the deployment.yaml files for K8s

JWT key:

substitute 'secretOrPrivateKey' with your own key:

kubectl create secret generic jwt-secret --from-literal=JWT_KEY=secretOrPrivateKey

now check

kubectl get secrets

Stripe API key:

get your Stripe API key from stripe.com

substitute 'yourStripeSecretKey' with your own key:

kubectl create secret generic stripe-secret --from-literal STRIPE_KEY=yourStripeSecretKey

now check

kubectl get secrets

For running K8s locally, ensure you have the Ingress-NGINX Loadbalancer installed

Install Ingress-NGINX Loadbalancer

kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v0.48.1/deploy/static/provider/cloud/deploy.yaml

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Tools for running K8s

Check out K9s !!

I found a great tool for monitoring your K8s cluster from your CLI with essentially ZERO config and setup:

https://github.com/derailed/k9s

brew install k9s
k9s

K9s screenshot:

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Run the App (client) locally

Since adding ticketing.dev to the /etc/hosts file, you can run the app in your browser (Chrome preferred) at ticketing.dev.

The Chrome browser is likely to respond to that request with a privacy warning and blocking that site:

To resolve this issue, just click anywhere on the browser screen and type "thisisunsafe" and you're good to go!

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Reflections on Troubleshooting

Deployments were failing with skaffold dev

My deployment.yaml files were missing a resource config for each container.

Here's the guide to fixing this: Managing Resources for Containers

This looked something like this:

resources:
    requests:
        cpu: '100m'
        memory: '100Mi'
    limits:
        cpu: '150m'
        memory: '150Mi'

Then my pods were being evicted due to node-pressure

...this was a tough one. At first I thought that too many pods were being deplyed at one time, so I added Pod prioritisation and scheduling:

Pod Priority and Preemption

I added a scheduling.yaml with multiple priority schedules (see pod-schedule-priority-classes.yaml), whick looks something like this:

apiVersion: scheduling.k8s.io/v1
kind: PriorityClass
metadata:
    name: first-priority
value: 1000000
preemptionPolicy: PreemptLowerPriority
globalDefault: false
description: 'This is a first priority class.'
---
apiVersion: scheduling.k8s.io/v1
kind: PriorityClass
metadata:
    name: second-priority
value: 900000
preemptionPolicy: PreemptLowerPriority
globalDefault: false
description: 'This is a second priority class.'
...

Still that didn't fix the node pressure problem, so I further researched...

K8s Taints & Tolerations ; and

K8s Node-pressure Eviction

...and added to my depyment.yaml files something like this:

priorityClassName: first-priority
            tolerations:
                - key: ''
                  operator: 'Exists'
                  effect: 'NoExecute'
                  tolerationSeconds: 120

Still no luck fixing the node-pressure problem.

FINALLY I found the culprit: it was the Docker preferences where I needed to tweak-up the Resource allowances for the environment :)

Docker Preferences -> Resources -> Advanced:

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kubectl fix

One of the errors running Skaffold has been:

Error from server (InternalError): error when creating "STDIN": Internal error occurred: failed calling webhook "validate.nginx.ingress. kubernetes.io": Post "https://ingress-nginx-controller-admission.ingress-nginx.svc:443/networking/v1beta1/ingresses?timeout=10s": dial tcp 10. 104.45.154:443: connect: connection refused

I found this fix to remove the Validating Webhook entirely:

kubectl delete -A ValidatingWebhookConfiguration ingress-nginx-admission

For a more fine grain approach to the above, check the config:

kubectl get validatingwebhookconfigurations

then, deleted any specific configuration using

kubectl delete validatingwebhookconfigurations [configuration-name]

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Kubernetes API reference

K8s API