Convert YAML string to dict in Helm template - go

Question

I am creating a chart for a project that has a binary that when executed generates a configuration file in YAML format that looks like this:
---
PARAM_1: value1
PARAM_2: value2
My chart needs to read this file and and load all of its values into environment variables in a container, so I created a variable config in my values.yaml file and when the chart is installed I am passing the file content using --set-file:
helm install <CHART> --set-file config=/path/to/yaml/config/file
Next I create a ConfigMap withe the value of .Values.config:
apiVersion: v1
kind: ConfigMap
metadata:
...
data:
{{ .Values.config }}
The problem I am having is that I need to do two things with values of config:
prefix all keys with a predefined value (so in the example above I would MY_APP_PARAM_1 as key)
make sure the values are all string, otherwise the ConfigMap will fail
How can I parse the value of .Values.config in my template as a dict so that I can use a range loop do these changes?

Answer 1

In the end I was able to do something like this:
{{ $lines := splitList "\n" .Values.config -}}
{{- range $lines }}
{{- if not (. | trim | empty) -}}
{{- $kv := . | splitn ":" 2 -}}
{{ printf "MY_APP_%s: %s" $kv._0 ($kv._1 | trim | quote) | indent 2 }}
{{ end -}}
{{- end -}}
I had a hard time getting the {{- vs {{ right, and helm install --debug --dry-run . help a lot in this part.
It's kind of messy, so I would be very interested in seeing if anyone has a better solution.

Answer 2

If You need to work with more tricky YAML (map in a map) You can use this:
List Handler (list to comma separated string)
{{- define "helm-toolkit.utils.joinListWithComma" -}}
{{- $local := dict "first" true -}}
{{- range $k, $v := . -}}{{- if not $local.first -}}, {{ end -}}{{ $v -}}{{- $_ := set $local "first" false -}}{{- end -}}
{{- end -}}
Convert Yaml dict to the properties-like look
{{- define "utils.yaml2properties" }}
{{- $yaml := . -}}
{{- range $key, $value := $yaml }}
{{- if kindIs "map" $value -}}
{{ $top:=$key }}
{{- range $key, $value := $value }}
{{- if kindIs "map" $value }}
{{- $newTop := printf "%s.%s" $top $key }}
{{- include "utils.yaml2properties" (dict $newTop $value) }}
{{- else if kindIs "slice" $value }}
{{ $top }}.{{ $key }}={{ include "helm-toolkit.utils.joinListWithComma" $value }}
{{- else }}
{{ $top }}.{{ $key }}={{ $value }}
{{- end }}
{{- end }}
{{- else if kindIs "slice" $value }}
{{ $key }}={{ include "helm-toolkit.utils.joinListWithComma" $value }}
{{- else }}
{{ $key }}={{ $value }}
{{- end }}
{{- end }}
{{- end }}
Use (example from K8s configMap)
{{- define "config.yaml" }}
vault.pki:
enabled: {{.Values.vault.pki.enabled}}
role: idverify
common-name: idverify
role:
map:
list:
- one
- two
{{- end }}
data:
bootstrap.properties: |
{{ (include "utils.yaml2properties" (include "config.yaml" . | fromYaml )) | indent 4 }}