The above will render the template when .Values.foo is defined, but will fail
to render and exit when .Values.foo is undefined.
## Using the 'tpl' Function
The `tpl` function allows developers to evaluate strings as templates inside a template.
This is useful to pass a template string as a value to a chart or render external configuration files.
Syntax: `{{ tpl TEMPLATE_STRING VALUES }}`
Examples:
```
# values
template: "{{ .Values.name }}"
name: "Tom"
# template
{{ tpl .Values.template . }}
# output
Tom
```
Rendering a external configuration file:
```
# external configuration file conf/app.conf
firstName={{ .Values.firstName }}
lastName={{ .Values.lastName }}
# values
firstName: Peter
lastName: Parker
# template
{{ tpl (.Files.Get "conf/app.conf") . }}
# output
firstName=Peter
lastName=Parker
```
## Creating Image Pull Secrets
Image pull secrets are essentially a combination of _registry_, _username_, and _password_. You may need them in an application you are deploying, but to create them requires running _base64_ a couple of times. We can write a helper template to compose the Docker configuration file for use as the Secret's payload. Here is an example:
