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‎k8s/HELM.md‎

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# Lab 10 — Helm Package Manager
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![difficulty](https://img.shields.io/badge/difficulty-intermediate-yellow)
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![topic](https://img.shields.io/badge/topic-Helm-blue)
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![points](https://img.shields.io/badge/points-12%2B2.5-orange)
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![tech](https://img.shields.io/badge/tech-Helm-informational)
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> Package your Kubernetes applications with Helm for reusable, configurable deployments across environments.
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---
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## Chart Overview
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This Helm chart (`myapp`) converts Kubernetes manifests from Lab 9 into a reusable, configurable deployment system.
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### Structure
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```
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myapp/
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├── Chart.yaml
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├── values.yaml
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├── values-dev.yaml
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├── values-prod.yaml
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└── templates/
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├── deployment.yaml
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├── service.yaml
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└── hooks/
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├── pre-install-job.yaml
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└── post-install-job.yaml
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````
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### Key Components
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- **Deployment template** — runs the Python application with configurable replicas, image, and resources
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- **Service template** — exposes the application inside cluster (NodePort / ClusterIP)
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- **Values files** — environment-based configuration (dev/prod)
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- **Hooks** — lifecycle jobs executed before and after deployment
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---
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## Configuration Guide
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### Main values (`values.yaml`)
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- `replicaCount` — number of pods
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- `image.repository` — Docker image name
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- `image.tag` — image version
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- `service.port` — exposed port
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- `service.targetPort` — container port (5000)
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- `resources` — CPU/memory limits
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- `livenessProbe` — health check configuration
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- `readinessProbe` — readiness check configuration
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### Dev environment (`values-dev.yaml`)
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- 1 replica
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- lightweight CPU/memory limits
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- NodePort service
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- relaxed probes
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### Prod environment (`values-prod.yaml`)
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- 3–5 replicas
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- higher resource limits
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- LoadBalancer-ready configuration
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- stricter probes
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### Example usage
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```bash
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helm install myapp-dev ./myapp -f values-dev.yaml
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helm install myapp-prod ./myapp -f values-prod.yaml
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````
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---
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## Hook Implementation
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### Pre-install hook
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Executes before deployment starts.
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* Used for initialization / validation
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* Runs a Kubernetes Job
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### Post-install hook
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Executes after deployment completes.
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* Used for smoke tests or verification
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* Confirms application readiness
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### Hook execution order
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```
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Pre-install → Deploy resources → Post-install
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```
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### Hook weights
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* `-5` → pre-install (runs first)
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* `5` → post-install (runs last)
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### Deletion policy
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Hooks are configured with:
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```
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hook-delete-policy: hook-succeeded
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```
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This ensures:
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* cleanup after successful execution
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* no leftover Jobs in cluster
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---
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## Installation Evidence
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### Helm release list
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```bash
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helm list
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```
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📸 Screenshot: `lab10-set.png`
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---
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### Kubernetes resources
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```bash
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kubectl get all
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```
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📸 Screenshot: `lab10-set.png`
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---
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### Application running
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```bash
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kubectl get pods
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kubectl get svc
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```
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📸 Screenshot: `lab10-app.png`
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---
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### Hooks execution
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```bash
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kubectl get jobs
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kubectl logs job/<pre-install-job>
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kubectl logs job/<post-install-job>
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```
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📸 Screenshot: `lab10-hooks.png`
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---
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## Operations
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### Install
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```bash
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helm install myapp-release ./myapp
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```
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### Upgrade
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```bash
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helm upgrade myapp-release ./myapp
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```
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### Rollback
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```bash
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helm rollback myapp-release 1
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```
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### Uninstall
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```bash
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helm uninstall myapp-release
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```
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---
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## Testing & Validation
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### Chart validation
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```bash
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helm lint ./myapp
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```
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### Template rendering
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```bash
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helm template myapp ./myapp
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```
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### Dry-run install
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```bash
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helm install test ./myapp --dry-run --debug
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```
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### Result
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* Deployment successfully created
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* Service exposed via NodePort
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* Application accessible in browser via `http://localhost:8080`
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---
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## Summary
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This Helm chart demonstrates:
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* templating Kubernetes manifests
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* environment-based configuration
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* lifecycle hooks (pre/post install)
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* production-ready structure
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* reusable deployment patterns
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Helm significantly improves maintainability, scalability, and repeatability of Kubernetes deployments.
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---
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## Screenshots
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### Cluster setup & Helm state
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![lab10-set](lab10-set.png)
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### Application running
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![lab10-app](lab10-app.png)
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### Hooks execution
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![lab10-hooks](lab10-hooks.png)

‎k8s/myapp/.helmignore‎

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# Patterns to ignore when building packages.
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# This supports shell glob matching, relative path matching, and
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# negation (prefixed with !). Only one pattern per line.
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.DS_Store
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# Common VCS dirs
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.git/
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.gitignore
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.bzr/
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.bzrignore
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.hg/
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.hgignore
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.svn/
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# Common backup files
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*.swp
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*.bak
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*.tmp
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*.orig
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*~
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# Various IDEs
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.project
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.idea/
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*.tmproj
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.vscode/

‎k8s/myapp/Chart.yaml‎

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apiVersion: v2
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name: myapp
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description: A Helm chart for Kubernetes
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# A chart can be either an 'application' or a 'library' chart.
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#
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# Application charts are a collection of templates that can be packaged into versioned archives
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# to be deployed.
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#
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# Library charts provide useful utilities or functions for the chart developer. They're included as
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# a dependency of application charts to inject those utilities and functions into the rendering
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# pipeline. Library charts do not define any templates and therefore cannot be deployed.
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type: application
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# This is the chart version. This version number should be incremented each time you make changes
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# to the chart and its templates, including the app version.
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# Versions are expected to follow Semantic Versioning (https://semver.org/)
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version: 0.1.0
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# This is the version number of the application being deployed. This version number should be
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# incremented each time you make changes to the application. Versions are not expected to
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# follow Semantic Versioning. They should reflect the version the application is using.
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# It is recommended to use it with quotes.
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appVersion: "1.16.0"

‎k8s/myapp/templates/_helpers.tpl‎

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{{/*
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Expand the name of the chart.
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*/}}
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{{- define "myapp.name" -}}
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{{- default .Chart.Name .Values.nameOverride | trunc 63 | trimSuffix "-" }}
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{{- end }}
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{{/*
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Create a default fully qualified app name.
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We truncate at 63 chars because some Kubernetes name fields are limited to this (by the DNS naming spec).
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If release name contains chart name it will be used as a full name.
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*/}}
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{{- define "myapp.fullname" -}}
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{{- if .Values.fullnameOverride }}
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{{- .Values.fullnameOverride | trunc 63 | trimSuffix "-" }}
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{{- else }}
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{{- $name := default .Chart.Name .Values.nameOverride }}
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{{- if contains $name .Release.Name }}
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{{- .Release.Name | trunc 63 | trimSuffix "-" }}
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{{- else }}
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{{- printf "%s-%s" .Release.Name $name | trunc 63 | trimSuffix "-" }}
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{{- end }}
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{{- end }}
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{{- end }}
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{{/*
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Create chart name and version as used by the chart label.
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*/}}
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{{- define "myapp.chart" -}}
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{{- printf "%s-%s" .Chart.Name .Chart.Version | replace "+" "_" | trunc 63 | trimSuffix "-" }}
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{{- end }}
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{{/*
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Common labels
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*/}}
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{{- define "myapp.labels" -}}
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helm.sh/chart: {{ include "myapp.chart" . }}
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{{ include "myapp.selectorLabels" . }}
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{{- if .Chart.AppVersion }}
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app.kubernetes.io/version: {{ .Chart.AppVersion | quote }}
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{{- end }}
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app.kubernetes.io/managed-by: {{ .Release.Service }}
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{{- end }}
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{{/*
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Selector labels
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*/}}
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{{- define "myapp.selectorLabels" -}}
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app.kubernetes.io/name: {{ include "myapp.name" . }}
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app.kubernetes.io/instance: {{ .Release.Name }}
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{{- end }}
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{{/*
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Create the name of the service account to use
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*/}}
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{{- define "myapp.serviceAccountName" -}}
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{{- if .Values.serviceAccount.create }}
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{{- default (include "myapp.fullname" .) .Values.serviceAccount.name }}
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{{- else }}
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{{- default "default" .Values.serviceAccount.name }}
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{{- end }}
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{{- end }}

‎k8s/myapp/templates/deployment.yaml‎

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apiVersion: apps/v1
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kind: Deployment
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metadata:
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name: {{ include "myapp.fullname" . }}
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spec:
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replicas: {{ .Values.replicaCount }}
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selector:
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matchLabels:
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app: {{ include "myapp.name" . }}
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template:
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metadata:
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labels:
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app: {{ include "myapp.name" . }}
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spec:
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containers:
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- name: app
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image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
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ports:
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- containerPort: {{ .Values.service.targetPort }}
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resources:
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{{- toYaml .Values.resources | nindent 12 }}
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livenessProbe:
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httpGet:
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path: {{ .Values.livenessProbe.path }}
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port: {{ .Values.service.targetPort }}
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initialDelaySeconds: {{ .Values.livenessProbe.initialDelaySeconds }}
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periodSeconds: {{ .Values.livenessProbe.periodSeconds }}
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readinessProbe:
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httpGet:
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path: {{ .Values.readinessProbe.path }}
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port: {{ .Values.service.targetPort }}
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initialDelaySeconds: {{ .Values.readinessProbe.initialDelaySeconds }}
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periodSeconds: {{ .Values.readinessProbe.periodSeconds }}

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