Working with Built-in Objects

1. Accessing Release Object (.Release.Name)

Property	Value	Description
.Release.Name	`string`	Name of the Helm release
.Release.Namespace	`string`	Kubernetes namespace where the release is installed
.Release.Revision	`integer`	Revision number of the release (1, 2, 3...)
.Release.IsInstall	`boolean`	True if this is an install operation
.Release.IsUpgrade	`boolean`	True if this is an upgrade operation
.Release.IsRollback	`boolean`	True if this is a rollback operation
.Release.Time	`time`	Timestamp of the release operation

Example: Using .Release.Name in a Template

apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ .Release.Name }}-config
data:
  releaseName: {{ .Release.Name }}

Note: The .Release.Name is particularly useful for generating unique resource names that are tied to the release name, ensuring no naming conflicts in multi-release environments.

2. Using Chart Object (.Chart.Name)

Property	Value	Description
.Chart.Name	`{{ .Chart.Name }}`	Chart name as defined in Chart.yaml

Example: Accessing Chart Name in Template

apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ .Chart.Name }}-config
data:
  chartName: {{ .Chart.Name }}

3. Accessing Files Object (.Files.Get)

The .Files object in Helm provides access to files within a chart or from external sources. The .Files.Get method allows you to read the contents of a file as a string.

Method	Description	Example
.Files.Get	Reads the content of a file as a string.	`.Files.Get "templates/config.yaml"`

Example: Reading a Config File

{{ .Files.Get "templates/config.yaml" }}

Note: The path is relative to the root of the chart.

Warning: Be cautious when using .Files.Get with large files as it loads the entire content into memory.

4. Using Capabilities Object (.Capabilities.KubeVersion)

Property	Value	Description
.Capabilities.KubeVersion	`{Major: "1", Minor: "28", GitVersion: "v1.28.0", GitCommit: "e40d35967f3b1282c31a91409d5b6a3947f82e5c", GitTreeState: "clean", BuildDate: "2023-09-14T15:06:00Z", GoVersion: "go1.21.1", Compiler: "gc", Platform: "linux/amd64"}`	Provides detailed version information of the Kubernetes cluster where the chart is being deployed

Example: Accessing KubeVersion in a Template

{{- if semverCompare "1.28" .Capabilities.KubeVersion.Version -}}
Kubernetes version is at least 1.28
{{- end -}}

Note: The .Capabilities.KubeVersion object provides access to the Kubernetes version information, which can be used for conditional logic in templates.

5. Working with Template Object (.Template.Name)

Property	Description	Example
.Template.Name	Provides the name of the current template being processed.	`{{ .Template.Name }}`

Example: Using .Template.Name in a Template

{{- range .Files.Lines }}
{{- if eq .Template.Name "my-template.yaml" }}
  {{ . }}
{{- end }}
{{- end }}

Note: The .Template.Name property is useful for conditional logic within templates, allowing you to apply different behaviors based on the template's name.

6. Accessing Release Service (.Release.Service)

Property	Description	Example
.Release.Service	Represents the Kubernetes service associated with the release	`.Release.Service`

Example: Using .Release.Service in a Template

{{- if .Release.Service }}
Service Name: {{ .Release.Service.Name }}
Service Namespace: {{ .Release.Service.Namespace }}
{{- end }}

Note: The .Release.Service object provides access to the Kubernetes service created during the release process, allowing templates to reference and utilize service details.

7. Getting Release Namespace (.Release.Namespace)

Property	Description	Example
.Release.Namespace	Namespace where the release is installed	`default`

Example: Accessing Release Namespace

apiVersion: v1
kind: Pod
metadata:
  name: example-pod
  namespace: {{ .Release.Namespace }}
spec:
  containers:
  - name: example-container
    image: nginx

Note: The .Release.Namespace value is automatically set during chart installation and reflects the namespace specified in the helm install command or the default namespace if none is provided.

8. Checking Release IsUpgrade (.Release.IsUpgrade)

Property	Value	Description
.Release.IsUpgrade	`false` or `true`	Boolean flag indicating if the release is an upgrade or a fresh install

Example: Using .Release.IsUpgrade in a Template

{{- if .Release.IsUpgrade }}
<h3>Upgrading Release</h3>
{{- else }}
<h3>Installing New Release</h3>
{{- end }}

Note: This property is available in the .Release object context and can be used to conditionally render templates based on whether the release is a fresh install or an upgrade.

9. Checking Release IsInstall (.Release.IsInstall)

Property	Value	Description
.Release.IsInstall	`false` / `true`	Boolean flag indicating if the current operation is an install (as opposed to an upgrade). Set to `true` during initial installation.

Example: Using .Release.IsInstall in a Template

{{- if .Release.IsInstall }}
&#x09;# This block runs only on install
&#x09;apiVersion: v1
&#x09;kind: ConfigMap
&#x09;metadata:
&#x09;&#x09;name: {{ include "myapp.fullname" . }}-install-config
&#x09;data:
&#x09;&#x09;message: "Welcome to the fresh installation!"
{{- end }}

10. Using Chart Version (.Chart.Version)

Property	Value	Description
.Chart.Version	`1.2.3`	Current version of the Helm chart as defined in `Chart.yaml`

Example: Accessing Chart Version in Template

{{ .Chart.Version }}

Note: The .Chart.Version field is read-only and reflects the version specified in the chart's Chart.yaml file.

11. Accessing Capabilities APIVersions (.Capabilities.APIVersions)

The .Capabilities.APIVersions field in Helm charts provides access to the Kubernetes API versions available in the cluster. This is useful for writing conditional logic based on the supported API versions.

Field	Description	Example Value
.Capabilities.APIVersions	A set of all API versions supported by the Kubernetes cluster	`["v1", "apps/v1", "batch/v1"]`

Example: Checking API Version Support

{{- if (has "batch/v1" .Capabilities.APIVersions) }}
apiVersion: batch/v1
kind: Job
metadata:
  name: example-job
spec:
  template:
    spec:
      containers:
      - name: job-container
        image: busybox
      restartPolicy: Never
{{- else }}
apiVersion: batch/v1beta1
kind: Job
metadata:
  name: example-job
spec:
  template:
    spec:
      containers:
      - name: job-container
        image: busybox
      restartPolicy: Never
{{- end }}