K
Q

helm getting subchart service names

3/7/2018

Whats the best way to get the helm subchart service names to reference into my ingress controller that will sit in the parent chart

values.yaml
---
ingress:
  paths:
    - serviceName: app-1
      path: /app-1/*
      port: 8080
    - serviceName: app-2
      path: /app-2/*
      port: 8080


ingress.yaml 
---
{{- range .Values.ingress.paths }}
          - path: {{ .path }}
            backend:
              {{- $subchart := .serviceName -}}
              serviceName: {{- include "$subchart.fullname" .}}
              servicePort: {{ .port }}
        {{- end }}

template: no template "$subchart.fullname" associated with template "gotpl"

-- doe1331
kubernetes
kubernetes-helm
yaml

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3 Answers

10/10/2019

It depends on the sub-chart definition!

As an example, elasticsearch chart, see here https://github.com/elastic/helm-charts/blob/master/elasticsearch/templates/service.yaml, is defining 2 services.

Both services name can be declared as value clusterName.

-- Thomas Decaux
Source: StackOverflow
5/15/2020

I have found that the best way to reference a service name is to override the template that they are using. There are some caveats to doing this however.

  1. The subchart and your chart will have different contexts so they will most likely render the template differently
  2. There are some things that are only available to the subchart

Most charts have a template similar to the one below in their _helpers.tpl file.

{{/*
Create a default fully qualified app name.
We truncate at 63 chars because some Kubernetes name fields are limited to this (by the DNS naming spec).
If release name contains chart name it will be used as a full name.
*/}}
{{- define "newchart.fullname" -}} 
{{- if .Values.fullnameOverride }}
{{- .Values.fullnameOverride | trunc 63 | trimSuffix "-" }}
{{- else }}
{{- $name := default .Chart.Name .Values.nameOverride }}
{{- if contains $name .Release.Name }}
{{- .Release.Name | trunc 63 | trimSuffix "-" }}
{{- else }}
{{- printf "%s-%s" .Release.Name $name | trunc 63 | trimSuffix "-" }}
{{- end }}
{{- end }}
{{- end }}

The subchart has different .Values to your chart. We will fix this when we render this template by creating a context that is similar to the subcharts context.

Instead of calling it with the . context we create a new context by replacing the .Values with the subcharts .Values.

{{ template "newchart.fullname" (set (deepCopy .) "Values" .Values.newchart }}

We use deepCopy so that we don't actually change the . context but rather create a new one to use.

The subchart has access to its own .Chart values that we can't replicate. In this case we will have to hardcode the value of .Chart.Name to the template. In this we can just replace it with the chart name newchart.

Once we have done this both nameOverride and fullnameOverride on the subchart will work without you having to manually change anything in your template files.

-- Kristinn Björgvin Árdal
Source: StackOverflow
3/7/2018

How about hardcoded subchart name scoped by release ?

{{ .Release.Name }}-<subchart_name>

-- Radek 'Goblin' Pieczonka
Source: StackOverflow