helm-templates

# Helm Templates

Working with Helm templates and template functions.

## Basic Templating

### Values Access

```yaml
apiVersion: v1
kind: Pod
metadata:
  name: {{ .Values.name }}
  namespace: {{ .Release.Namespace }}
spec:
  containers:
  - name: {{ .Chart.Name }}
    image: "{{ .Values.image.repository }}:{{ .Values.image.tag | default .Chart.AppVersion }}"
```

### Built-in Objects

- `.Values`: Values from values.yaml and overrides
- `.Release`: Release information (Name, Namespace, IsUpgrade, IsInstall)
- `.Chart`: Chart metadata from Chart.yaml
- `.Files`: Access non-template files in chart
- `.Capabilities`: Kubernetes cluster capabilities
- `.Template`: Current template information

## Template Functions

### String Functions

```yaml
# upper, lower, title
name: {{ .Values.name | upper }}

# quote
value: {{ .Values.password | quote }}

# trimSuffix, trimPrefix
image: {{ .Values.image | trimSuffix ":latest" }}

# replace
url: {{ .Values.url | replace "http" "https" }}
```

### Default Values

```yaml
# default function
port: {{ .Values.port | default 8080 }}
tag: {{ .Values.image.tag | default .Chart.AppVersion }}

# required function
database: {{ required "database.host is required" .Values.database.host }}
```

### Type Conversion

```yaml
# toString, toJson, toYaml
replicas: {{ .Values.replicas | toString }}

annotations:
{{ toYaml .Values.annotations | indent 2 }}

config: |
{{ toJson .Values.config | indent 2 }}
```

### Conditionals

```yaml
{{- if .Values.ingress.enabled }}
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: {{ .Release.Name }}
spec:
  # ...
{{- end }}

{{- if and .Values.persistence.enabled .Values.persistence.existingClaim }}
# Use existing claim
{{- else if .Values.persistence.enabled }}
# Create new claim
{{- end }}
```

### Loops

```yaml
{{- range .Values.environments }}
- name: {{ .name }}
  value: {{ .value | quote }}
{{- end }}

{{- range $key, $value := .Values.config }}
{{ $key }}: {{ $value | quote }}
{{- end