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istio

How to update Istio configuration after installation?

Every document I found only tells you how to enable/disable a feature while installing a new Istio instance. But I think in a lot of cases, people need to update the Istio configuration.

  • Accessing External Services, in this instance, it says I need to provide <flags-you-used-to-install-Istio>, but what if I don't know how the instance was installed?
  • Address auto allocation, in this instance, it doesn't mention a way to update the configuration. Does it imply this feature has to be enabled in a fresh installation?

Why there's no istioctl update command?

Solution

  • The confusion totally makes sense. As at least it would be nice for it to be called out somewhere.

    Basically, there is no update command for the same reason as there is no kubectl update command. What istioctl does is generate the YAML output which represents in a declarative way how your application should be running. And then applies it to the cluster and Kubernetes handles it.

    So basically istioctl install with the same values will produce the same output and when applied to Kubernetes, if there were no changes, nothing will be updated.