container.training/slides/exercises/helm-umbrella-chart-details.md

Exercise — Umbrella Charts

• We want to deploy dockercoins with a single Helm chart

• That chart will reuse the "generic chart" created previously

• This will require expressing dependencies, and using the alias keyword

• It will also require minor changes in the templates

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Goal

• We want to be able to install a copy of dockercoins with:

  helm install dockercoins ./umbrella-chart
  

• It should leverage the generic chart created earlier

  (and instanciate it five times, one time per component of dockercoins)

• The values YAML files created earlier should be merged in a single one

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Bonus

• We want to replace our redis component with a better one

• We're going to use Bitnami's redis chart

  (find it on the Artifact Hub)

• However, a lot of adjustments will be required!

  (check following slides if you need hints)

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Hints (1/2)

• We will probably have to disable persistence

  • by default, the chart enables persistence

  • this works only if we have a default StorageClass

  • this can be disabled by setting a value

• We will also have to disable authentication

  • by default, the chart generates a password for Redis

  • the dockercoins code doesn't use one

  • this can also be changed by setting a value

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Hints (2/2)

• The dockercoins code connects to redis

• The chart generates different service names

• Option 1:

  • vendor the chart in our umbrella chart
  • change the service name in the chart

• Option 2:

  • add a Service of type ExternalName
  • it will be a DNS alias from redis to redis-whatever.NAMESPACE.svc.cluster.local
  • for extra points, make the domain configurable