• k8s
• helm
• examples

k8s helm examples script pieces

• https://hackernoon.com/the-art-of-the-helm-chart-patterns-from-the-official-kubernetes-charts-8a7cafa86d12

• Add extraEnv values to chart #1 with

  {{- range $key, $value := .Values.extraEnv -}}
  - name: {{ $key }}
  - value: {{ $value -}}
  {{- end }}

• Add extraEnv values to chart #2 as string and then parse through tpl(template)

  # in values.yaml
  extraEnv: |
   - name: KEYCLOAK_LOGLEVEL
     value: DEBUG
   - name: HOSTNAME
     value: {{ .Release.Name }}-keycloak
  
  # and in template
  {{- with .Values.keycloak.extraEnv }}{{ tpl . $ | indent 12 }}{{- end }}

• Referencing Mutually-deployed Resources e.g. db password

  # use trick above passing string that can be parsed in deployment and vars replaced
  extraEnv: |. #String to be parsed through tpl
    - name: POSTGRES_USER
      value: {{ .Values.postgresql.postgresUser }}
    - name: POSTGRESS_PASSWORD
      valueFrom:
        secretKeyRef:
          name: {{ .Release.Name }}-postgresql
          key: postgres-password

• parse vars into file imported into ConfigMap or Secret

  # https://stackoverflow.com/questions/47595295/how-do-i-load-multiple-templated-config-files-into-a-helm-chart/52009992#52009992
  conf_file1: {{ tpl (.Files.Get "files/conf_file1") . | quote }}
  
  #load into a Secret we need to encode the content in base64:
  conf_file1: {{ tpl (.Files.Get "files/conf_file1") . | b64enc | quote }}
  
  #load a set of files into a ConfigMap using .Files.Glob :
  {{ (tpl (.Files.Glob "files/*").AsConfig . ) | indent 2 }}

• To update deployment when a config, changes, add the sha1 of the config as annotation to deployment.
  • A change in the annotation will force a redeploy

  • e.g. deployment.yaml

    {{/* 1. Generate checksums for config changes once, then loop through deployments */}}
    {{- define "config-checksums" }}
      {{- range $path, $bytes := $.Files.Glob "files/**" }}
    {{- base $path }}={{ tpl ( $.Files.Get $path ) $ | sha1sum }}
      {{- end }}
    {{- end }}
    {{ $chk := include "config-checksums" . | sha1sum  }}
    ---
    kind: Deployment
    spec:
      template:
        metadata:
          annotations:
            config/checksums: {{ $chk }}
    ...

}}}