Have you written Helm charts and manifests from scratch?

Yes, I have had to write Helm charts and Kubernetes manifests from scratch. I usually started with describing the necessary resources: Deployment, Service, ConfigMap, Secret, etc. In Helm charts, I used templates with parameterization through values.yaml, which allowed flexible configuration of deployments for different environments.

An example of a simple Helm template for Deployment:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ .Release.Name }}-app
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      app: {{ .Release.Name }}
  template:
    metadata:
      labels:
        app: {{ .Release.Name }}
    spec:
      containers:
        - name: app-container
          image: {{ .Values.image.repository }}:{{ .Values.image.tag }}
          ports:
            - containerPort: 80

This approach allows creating reusable and customizable charts for various applications.