Helm templating seems to only render alphabetically - kubernetes-helm

Question

Im trying to template volumes and volumemounts in a deployment.
The output i want is:
volumeMounts:
- name: appsettings
mountPath: /usr/share/nginx/html/appsettings.json
subPath: appsettings.json
volumes:
- name: appsettings
configMap:
name: appsettings-file
Here is my values.yml:
volumemounts:
- name: appsettings
mountPath: /usr/share/nginx/html/appsettings.json
subPath: appsettings.json
volumes:
- name: appsettings
configMap:
name: appsettings-file
Here is my template:
{{- with .Values.volumemounts }}
volumeMounts:
{{- toYaml . | nindent 4 }}
{{- end }}
{{- with .Values.volumes }}
volumes:
{{- print . | nindent 4 }}
{{- end }}
Here is the output:
volumeMounts:
- mountPath: /usr/share/nginx/html/appsettings.json
name: appsettings
subPath: appsettings.json
volumes:
- configMap:
name: appsettings-file
name: appsettings
If i change line 2 and 6 in values.yml to be - aname: appsettings
The output is:
volumeMounts:
- aname: appsettings
mountPath: /usr/share/nginx/html/appsettings.json
subPath: appsettings.json
volumes:
- aname: appsettings
configMap:
name: appsettings-file
So it seems helm always gets the array in alphabetical order.
(i also tried with print instead of toYaml, ofcourse it gave an error but i saw that it still fetched they array sorted alphabeticaly:[map[configMap:map[name:appsettings-file] name:appsettings]])
What am i missing ? How should i do this ?

Answer 1

toYaml in fact alphabetizes dictionary keys. This doesn't usually matter; Kubernetes will treat both versions of the pod spec the same. If you want the dictionary to be serialized in a specific order, you'll need to write out the keys by hand.
In this particular case, I probably wouldn't try to make this low-level detail of the pod spec be configurable. I'd write it out in the template file instead. If this entire ConfigMap mount is optional, put it behind a single shared {{ if .Values.mountConfig }} option. That would also remove the toYaml call.