helm 的逻辑和流程控制

## if else 条件判断
```
#格式
{{- if }}
{{- else }}
{{- end}}
```
实例
```yaml
# values.yaml
Person:
  name: david
  age: 20
  sex: man
work: IT
Ingress:
  enabled: false
  
  
# configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
   name: {{ .Release.Name }}-configmap
   namespace: {{ .Release.Namespace }}
data:
   name: {{ .Values.Person.name | default "noone" | quote }}
   age: {{ .Values.Person.age | quote }}
   sex: {{ .Values.Person.sex | upper | quote }}
   {{- if .Values.Ingress.enabled }}
   ingress: "配置 ingress"
   {{- else }}
   ingress: "不配置 ingress"
   {{- end }}
   {{- if eq .Values.work "IT"}}
   work: "work变量 等于 it"
   {{- else }}
   work: "work 不等于it"
   {{- end }}
   
## 输出
# Source: mychart/templates/configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: mychart-configmap
  namespace: default
data:
  name: "david"
  age: "20"
  sex: "MAN"
  ingress: "不配置 ingress"
  work: "work变量 等于 it"
```

## with 变量作用域
```
#values.yaml
Person:
  info:
    name: david
    age: 20
    sex: man
	
# configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ .Release.Name }}-configmap
  spacename: {{ .Release.Namespace }}
data:
  {{- with .Values.Person.info }} #避免重复写 .Values.Person.info
  name: {{ .name | default "noone" }}
  age: {{ .age | quote }}
  sex: {{ .sex | upper }}
  {{- end }}
  
 # show
 # Source: mychart/templates/configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: mychart-configmap
  spacename: default
data:
  name: david
  age: "20"
  sex: MAN
```

## range 遍历
```
## values.yaml
Location:
  - beijing
  - shanghai
  - guangzhou
  - hongkang
## configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ .Release.Name }}-configmap
  spacename: {{ .Release.Namespace }}
data:
  {{- range .Values.Location }}
  - {{ . | title }}
  {{- end }}
## show
# Source: mychart/templates/configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: mychart-configmap
  spacename: default
data:
  - Beijing
  - Shanghai
  - Guangzhou
  - Hongkang
```

也可以在template 定义 tuple

```
apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ .Release.Name }}-configmap
  spacename: {{ .Release.Namespace }}
data:
  {{- range .Values.Location }}
  - {{ . | title }}
  {{- end }}
  {{- range tuple "SH" "HK" "BJ" }}  #直接遍历tuple 中的元素
  - {{ . }}
  {{- end }}
```

helm 的逻辑 和 流程控制

helm 的逻辑和流程控制