Inheritance of multiline helm chart template - kubernetes

Question

I want to set resources to pods with helm chart with template of resource section from subchart. Because it should be several different reource templates in subchart.
I have values.yaml , main-values.yaml and templates/deployment.yaml
The command to update helm chart is
helm upgrade -i mynamespace ./kubernetes/mynamespace --namespace mynamespace --create-namespace -f kubernetes/mynamespace/main-values.yaml --reset-values
Files are cuted to show just an example:
main-values.yaml :
namespace: mynamespace
baseUrl: myurl.com
customBranch: dev
components:
postgresql:
nodeport: 5432
elasticsearch:
nodeport: 9200
resources_minimum:
requests:
memory: "100M"
cpu: "100m"
limits:
memory: "300M"
cpu: "200m"
values.yaml
namespace:
baseUrl:
customBranch:
components:
service:
name: service
image: docker-registry.service.{{ .Values.customBranch }}
imagePullPolicy: Always
resources: "{{ .Values.resources_minimum }}"
tag: latest
port: 8080
accessType: ClusterIP
cut
And deployment.yaml is
cut
containers:
- name: {{ $val.name }}
securityContext:
{{- toYaml $.Values.securityContext | nindent 12 }}
image: "{{ tpl $val.image $ }}:{{ $val.tag | default "latest" }}"
imagePullPolicy: {{ $val.imagePullPolicy }}
resources: "{{ tpl $val.resources $ }}"
cut
And the deployment section of resources does not work at all. However image section with intermediate template {{ .Values.customBranch }} works and nodeport template works fine in services.yaml
spec:
type: {{ $val.accessType }}
ports:
- port: {{ $val.port }}
name: mainport
targetPort: {{ $val.port }}
protocol: TCP
{{ if and $val.nodeport }}
nodePort: {{ $val.nodeport }}
I've tried $val, toYaml, tpl , and plain $.Values options in resources section of deployment.yaml and got several errors like:
error converting YAML to JSON: yaml: invalid map key: map[interface {}]interface {}{".Values.resources_minimum":interface {}(nil)}
or
error converting YAML to JSON: yaml: line 29: could not find expected ':'
and other error like so.
Is it impossible to push yaml values of multiline resources_minimum through values.yaml to deployment.yaml?
Which syntax should I use?
What documentation can you advice me to read?

Answer 1

It's not possible to use template code in values.yaml files.
But you can merge several values.yaml files to reuse configuration values.
main-values.yaml
components:
service:
image: docker-registry.service.dev
resources:
requests:
memory: "100M"
cpu: "100m"
limits:
memory: "300M"
cpu: "200m"
values.yaml
components:
service:
name: service
imagePullPolicy: Always
tag: latest
port: 8080
accessType: ClusterIP
If you add this to your template, it will contain values from both value files:
components: {{ deepCopy .Values.components | merge | toYaml | nindent 6 }}
merge + deepCopy will merge the values of all your values files.
toYaml will output the result in yaml syntax.
You also have to check the correct indentation. 6 is just a guess.
Call helm template --debug ...
This generates even invalid yaml output where you can easily check the correct indentation and see other errors.

Answer 2

Ok. Fellows helped me with elegant solution.
values.yaml :
resource_pool:
minimum:
limits:
memory: "200M"
cpu: "200m"
requests:
memory: "100M"
cpu: "100m"
...
components:
service:
name: service
image: docker.image
imagePullPolicy: Always
tag: latest
resources_local: minimum
And deployment.yaml :
{{- range $keyResources, $valResources := $.Values.resource_pool }}
{{- if eq $val.resources_local $keyResources }}
{{ $valResources | toYaml | nindent 12}}
{{- end }}
{{- end }}
Any sugestion what to read to get familiar with all Helm trics?