[kubernetes 패키지 관리자] Helm 설치 및 기본 사용법

Helm usage

Setup example project

helm create mychart
rm -rf mychart/templates/*

configmap.yaml

helm install full-coral .
helm get manifest full-coral
helm uninstall full-coral

# test template rendering
helm install --debug --dry-run goodly-guppy .

Built-in objects

https://helm.sh/docs/chart_template_guide/builtin_objects/

• Release:
  • Release.Name
  • Release.Namespace: The namespace to be released into (if the manifest doesn’t override)
  • Release.IsUpgrade: This is set to true if the current operation is an upgrade or rollback.
  • Release.IsInstall: This is set to true if the current operation is an install.
  • Release.Revision: The revision number for this release. On install, this is 1, and it is incremented with each upgrade and rollback.
  • Release.Service: The service that is rendering the present template. On Helm, this is always Helm.

values

• values.yaml에 넣은 내용을 {{ .Values. }} 템플릿 문법으로 사용 가능
• helm install --set myvalue=value로 override 가능
• --set myvalue=null로 제거 가능

Template functions and pipeline

• Template function: 대부분 Go template 함수에서 가져옴. https://godoc.org/text/template

Pipelines

apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ .Release.Name }}-configmap
data:
  myvalue: "Hello World"
  drink: {{ quote .Values.favorite.drink  }} # use template
  food: {{ .Values.favorite.food | upper | quote }} # use pipelines

Using default function

• 가장 많이 쓰이는 함수 중 하나. 값이 없으면 default value 사용
• 실제로는 잘 안쓰이고 모든 값이 values.yaml에 있어야됨. 아래에 나오는 if 등과 같이 사용

drink: {{ .Values.favorite.drink | default "tea" | quote }}

Flowcontrol

• if/else
• with
• range
• define
• template: imports a named template
• block

{{ if PIPELINE }}
  # Do something
{{ else if OTHER PIPELINE }}
  # Do something else
{{ else }}
  # Default case
{{ end }}

예시

apiVersion: v1
kind: ConfigMap
metadata:
  name: mychart-configmap
  name: {{ .Release.Name }}-configmap
data:
  myvalue: "Hello World"
  drink: {{ .Values.favorite.drink | default "tea" | quote }}
  food: {{ .Values.favorite.food | upper | quote }}
  {{ if eq .Values.favorite.drink "coffee"}}mug: true{{end}}

아래와 같이 whitespace 맞춰줄 수 있음 ({{- ... -}})

...
  food: {{ .Values.favorite.food | upper | quote }}
  {{- if eq .Values.favorite.drink "coffee" }}
  mug: true
  {{- end }}

Variables

$name, :-를 사용하여 variable 사용 가능

apiVersion: v1
kind: ConfigMap
metadata:
  name: mychart-configmap
  name: {{ .Release.Name }}-configmap
data:
  myvalue: "Hello World"
  {{- $relname := .Release.Name -}}
  {{- with .Values.favorite }}
  drink: {{ .drink | default "tea" | quote }}
  food: {{ .food | upper | quote }}
  release: {{ $relname }}
  {{- end }}
  toppings: |-
    {{- range $index, $topping := .Values.pizzaToppings }}
      {{ $index }}: {{ $topping }}
    {{- end }}

이런식으로 key, value로 지정하게 쓰임

...
  {{- range $key, $val := .Values.favorite }}
  {{ $key }}: {{ $val | quote }}
  {{- end }}