Optional: 7. Create your own chart on IT-CNE Cloud-Native Core

7.1 Refactor 1

Mon, 01 Jan 0001 00:00:00 +0000

Task 7.1.1: Make the Ingress resource more configurable

After cloning the repository and inspecting the templates already created for you, you will notice some potential for improvement. For example the hostname of the applications should not be hard-coded. When deploying to multiple environments you will run into conflicts.

Modify the consumer and producer ingress templates and extract following variables to make them configurable:

Extract .spec.rules.host as value
Extract .spec.tls.hosts[0] as value, use the same value as above

Note

If you want to test the chart locally you can execute following command

helm template -s templates/consumer-ingress.yaml ./helm-basic-chart --debug | cat -n -

7.2 Refactor 2

Mon, 01 Jan 0001 00:00:00 +0000

If you take a closer look at your Chart you will still recognize some weak spots. For example the producer and consumer will look like a lot of code duplication. We don’t like code duplication at all! The only big difference is the "consumer" or "producer" pre- or suffixed everywhere.

Just for fun: How much lines of code are actually different?

Hint / Solution


bc -l <<< "$(diff -U0 templates/consumer-deployment.yaml templates/producer-deployment.yaml | wc -l)"/2

When considering the differences and how they affect the service, we can easily see the flaw of this Chart. The entire Chart is a duplication. Both services could use the same Chart and just be two instances / releases!

7.3 Composition

Mon, 01 Jan 0001 00:00:00 +0000

Instead of instantiating the Chart two times manually by hand, we can also define a composition of two Charts in a single Chart. In other 2words we create a new Helm Chart and add the Chart we just wrote twice as a dependency to the chart.

In Helm we can make a composition of already existing Charts and own templates and define it as a new Chart. This is a very common use case if we mix self created resources with own templated resources.