Kubecon 2017 talk on Helm chart patterns found by maintaining the Kubernetes Charts repo. Recording of the talk is available here: https://www.youtube.com/watch?v=WugC_mbbiWU

1. Vic Iglesias
Cloud Solutions Architect
@vicnastea
Lessons Learned from
the Charts Repo

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Vic Iglesias
● Cloud Solutions Architect
● Santa Barbara, CA
● viglesias@google.com
● @vicnastea

3. Agenda Slide
01
02
03
04
05
Helm 101
The kubernetes/charts Repo
Chart Structure
Chart Tricks
What’s Next?

4. 01 Helm 101

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Helm Basics
● Helm is an OSS tool that streamlines installing and
managing Kubernetes applications.
● Helm has two parts
○ Client (helm) on your laptop or CI/CD system
○ Server (tiller) in your Kubernetes cluster
● Helm is the equivalent of Apt or Yum in the OS
packaging world

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Chart Basics
● Charts are Helm packages that contain:
○ A description of the package (Chart.yaml)
○ One or more templates, which contain Kubernetes
manifest files
● Charts can be stored locally on disk or fetched from
remote repositories
● Charts are the equivalent of Debs or RPMs in the OS
packaging world

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What is a Kubernetes “Application”?
Pods Config Volumes SecretsServices

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What is a Kubernetes “Application”?
Pods Config Volumes SecretsServices

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What is a Kubernetes “Application”?
Pods Config Volumes Services

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What is a Kubernetes “Application”?
Pods Config Volumes Services

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What is a Kubernetes “Application”?
YAML YAML YAML YAML

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Create a Config API to your Application
Pods Config Volumes Services

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Create a Config API to your Application
Pods Config Volumes Services

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Create a Config API to your Application
Pods Config Volumes Services
Config

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Create a Config API to your Application
Pods Config Volumes Services
Config

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Rollback your Application as a Unit
VERSION 1

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Rollback your Application as a Unit
VERSION 1 VERSION 2

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Rollback your Application as a Unit
VERSION 1 VERSION 2

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Rollback your Application as a Unit
VERSION 2

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Rollback your Application as a Unit
VERSION 1 VERSION 2

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Rollback your Application as a Unit
VERSION 1

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Rollback your Application as a Unit
VERSION 1 VERSION 3

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Go Templating - values.yaml

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Go Templating - templates/deployment.yaml

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Go Templating - templates/service.yaml

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Sprig Functions - templates/service.yaml

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Sprig Functions
● String Functions: trim, wrap, randAlpha, plural, etc.
● Math Functions: add, max, mul, etc.
● Date Functions: now, date, etc.
● Defaults Functions: default, empty, coalesce
● Encoding Functions: b64enc, b64dec, etc.
● Lists and List Functions: list, first, uniq, etc.

28. 02 The kubernetes/charts repo

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What?
● https://github.com/kubernetes/charts
● Centralized repository hosting community
curated Helm Charts
● Continuous integration
● Code review provided by maintainers
● Default repository configured in Helm

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Why?
"Standards" by Randall Munroe is licensed under CC BY-NC 2.5

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Stats
● 130+ Charts
● 2000+ PRs
● ~100 Contributors

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Commits over time

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Weekly visitors

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Number of Forks

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Number of Forks

36. 03 Chart Structure

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Chart Structure
● Chart.yaml
● values.yaml
● README.md
● requirements.yaml
● templates/
● templates/NOTES.txt

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Chart.yaml

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values.yaml

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values.yaml
Flexible
Reproducible
Start Here
Move this way

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requirements.yaml

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templates folder

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NOTES.txt

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README.md

45. 04 Chart Tricks

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Use helm create

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Use helm create with starter templates

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Update deployments on config change

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Update deployments on config change

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Run out of band steps with hooks

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Helm Hook Types
Before or after:
● Install
● Delete
● Upgrade
● Rollback

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Allow reuse of existing PVC for data

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Allow optional ingress config

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Create a functional test (even if it is simple)

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Create a functional test (even if it is simple)

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Allow use custom ConfigMaps

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Namespace your helper templates

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Conditional Dependencies

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Conditional Dependencies

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Use toYaml to give users more flexibility

61. 05 What’s Next?

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Future work
● Allow OWNERS file to dictate who can merge
● Delegate responsibility of charts to other Git repositories
● Purge unmaintained charts
● More functional tests for charts

63. Thank You!
@vicnastea
viglesias@google.com