Built-in Objects
Objects are passed into a template from the template engine. And your code can
pass objects around (we’ll see examples when we look at the with
and range
statements). There are even a few ways to create new objects within your
templates, like with the tuple
function we’ll see later.
Objects can be simple, and have just one value. Or they can contain other
objects or functions. For example. the Release
object contains several objects
(like Release.Name
) and the Files
object has a few functions.
In the previous section, we use {{ .Release.Name }}
to insert the name of a
release into a template. Release
is one of the top-level objects that you can
access in your templates.
Release
: This object describes the release itself. It has several objects inside of it:Release.Name
: The release nameRelease.Namespace
: The namespace to be released into (if the manifest doesn’t override)Release.IsUpgrade
: This is set totrue
if the current operation is an upgrade or rollback.Release.IsInstall
: This is set totrue
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 alwaysHelm
.
Values
: Values passed into the template from thevalues.yaml
file and from user-supplied files. By default,Values
is empty.Chart
: The contents of theChart.yaml
file. Any data inChart.yaml
will be accessible here. For example{{ .Chart.Name }}-{{ .Chart.Version }}
will print out themychart-0.1.0
.- The available fields are listed in the Charts Guide
Files
: This provides access to all non-special files in a chart. While you cannot use it to access templates, you can use it to access other files in the chart. See the section Accessing Files for more.Files.Get
is a function for getting a file by name (.Files.Get config.ini
)Files.GetBytes
is a function for getting the contents of a file as an array of bytes instead of as a string. This is useful for things like images.Files.Glob
is a function that returns a list of files whose names match the given shell glob pattern.Files.Lines
is a function that reads a file line-by-line. This is useful for iterating over each line in a file.Files.AsSecrets
is a function that returns the file bodies as Base 64 encoded strings.Files.AsConfig
is a function that returns file bodies as a YAML map.
Capabilities
: This provides information about what capabilities the Kubernetes cluster supports.Capabilities.APIVersions
is a set of versions.Capabilities.APIVersions.Has $version
indicates whether a version (e.g.,batch/v1
) or resource (e.g.,apps/v1/Deployment
) is available on the cluster.Capabilities.KubeVersion
andCapabilities.KubeVersion.Version
is the Kubernetes version.Capabilities.KubeVersion.Major
is the Kubernetes major version.Capabilities.KubeVersion.Minor
is the Kubernetes minor version.
Template
: Contains information about the current template that is being executedName
: A namespaced file path to the current template (e.g.mychart/templates/mytemplate.yaml
)BasePath
: The namespaced path to the templates directory of the current chart (e.g.mychart/templates
).
The built-in values always begin with a capital letter. This is in keeping with Go’s naming convention. When you create your own names, you are free to use a convention that suits your team. Some teams, like the Kubernetes Charts team, choose to use only initial lower case letters in order to distinguish local names from those built-in. In this guide, we follow that convention.