Helm: generate comma separated list

Another quick way of doing it:

{{- define "helm-toolkit.utils.joinListWithComma" -}}
{{- $local := dict "first" true -}}
{{- range $k, $v := . -}}{{- if not $local.first -}},{{- end -}}{{- $v -}}{{- $_ := set $local "first" false -}}{{- end -}}
{{- end -}}

If you give this input like:

test:
- foo
- bar

And call with:

{{ include "helm-toolkit.utils.joinListWithComma" .Values.test }}

You'll get the following rendered:

foo,bar

This is from OpenStack-Helm's Helm-toolkit chart, which is a collection of utilities for similar purposes.

For those from 2020+ it now can be achieved as simple as that:

{{ join "," .Values.some.array }}

It produces the correct output: value: "test1,test2,test3"

At least it works with (more or less) recent versions of helm-cli:

Client: &version.Version{SemVer:"v2.16.2", GitCommit:"bbdfe5e7803a12bbdf97e94cd847859890cf4050", GitTreeState:"clean"}