golang模板-默认的语义如何

Question

Looking at helm charts, there is often something like:

{{- default .Chart.Name .Values.nameOverride | trunc 63 | trimSuffix "-" -}}

I could not find anything about the default function(?) in the template docs:

https://golang.org/pkg/text/template/

What is the semantics of it? Are there any kind of arguments possible?

Answer 1

It comes from the library sprig, which is used by Helm. Quoting the docs:

default "foo" .Bar 

In the above, if .Bar evaluates to a non-empty value, it will be used. But if it is empty, foo will be returned instead.