Reference previously declared value in HELM values.yaml

Question

I have a HELM Chart with a few requirements (i.e. subcharts).

When deploying that chart, I use a values.yaml containing all the values for both the main chart and the subcharts :

globalFoo: "bar"

subchart1:
  foo: subchart1-{{ globalFoo }}

subchart2:
  localFoo: "bar2"
  foo: subchart2-{{ subchart2.localFoo }}

I'd like to achieve two things :

Reference a previously declared global variable (i.e. in the global chart scope) in a subchart value (subchart1.foo in my example)
Reference a previously declared local variable in the same subchart scope (subchart2.foo in my example)

The exemple above doesn't work. I tried several syntaxes and none of them worked. I didn't find anything like that in the HELM documentation.

Is it doable ?

miraculixx miraculixx · Accepted Answer · 2021-06-07T13:33:56

Reference a previously declared global variable in a subchart value, Reference a previously declared local variable in the same subchart scope

This can be achieved to some extent using anchors and aliases.

global: 
   foo: &global-foo bar
   
subchart1:
  # this verbatim copies the content of the anchor
  foo: *global-foo
  local: &subchart1-local bar 

subchart2:
  foo: *subchart1-local

Values can naturally be combined in a helm template:

kind: ConfigMap
...
data:
   FOO: "subchart2-{{ .Values.subchart2.foo }}"

If find yourself needing "templated values" the tpl function may be helpful:

# values 
global:
   user: foo
   pass: bar 
   dbhost: dbserver.com

mychart:
   connection: "db://{{.d.user}}:{{d.pass}}/{{d.dbhost}}"

# template
kind: ConfigMap
...
data:
   DBURL: "{{ tpl .Values.mychart.connection (dict "d" .Values.global "Template" $.Template }}"

Note the (dict ...) syntax is derived from a hint in this helm github comment. This helps to shorten the template string by giving the ".d" context instead ".Values", i.e. .d.user is short for .Values.global.user

Reference previously declared value in HELM values.yaml

2 Answers