• Helm: Include definitions on templates

  2 min read

  
  

  Sometimes we might need to add the same content twice on the same Helm chart. A tipical example would be the labels on the Pods that need to match the selectos on the Service. For this when you create a helm chart there are already some default definitions, for example:

  {{/*
  Common labels
  */}}
  {{- define "pet2cattle.labels" -}}
  helm.sh/chart: {{ include "pet2cattle.chart" . }}
  {{ include "pet2cattle.selectorLabels" . }}
  app.kubernetes.io/managed-by: {{ .Release.Service }}
  {{- end }}
  
  {{/*
  Selector labels
  */}}
  {{- define "pet2cattle.selectorLabels" -}}
  app.kubernetes.io/name: {{ include "pet2cattle.name" . }}
  app.kubernetes.io/instance: {{ .Release.Name }}
  {{- end }}
  

  16/11/2021

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• Helm template: Array to a comma separated string

  2 min read

  
  

  While writing Helm charts we might need to transform some values that are going to be defined as an array as a value into a comma separated string

  12/11/2021

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• Kubernetes / AWS node termination handler: Drain spot instances that are about to be terminated

  3 min read

  If you are using a mixed policy on your EKS workers ASG you will want to install the AWS node termination handler to drain a node once AWS notifies that a particular spot instance is going to be reclaimed

  29/09/2021

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• Using helm hooks to when certain objects are created

  3 min read

  
  

  Sometimes when we are writing a helm chart we realize that we have some parts of the task that need to be performed before of after deploying certain objects. We can also need to execute some Jobs in order to, for example, update the database, but not continuously, just when we update the application.

  To handle this kind of situations we can use helm hooks

  19/08/2021

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• Conditional expressions in helm

  2 min read

  
  

  Maybe one of the main challenges about helm is the complexity of it's template rendering engine: It's not very intuitive

  14/07/2021

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