Add Helm Chart for the OpenSearch cluster CR

[IshaGirdhar]

This fixes #448
PR to add Helm Chart to install OpenSearch cluster CR.

[idanl21]

Installed and it working great! didn't tested all values fields, but the example is working great.
it is big improvment, im still thinking about how to add some test for that so it will not break in the future.
Also, please add here https://github.com/Opster/opensearch-k8s-operator/blob/85140dfba76aee74f57867997f89d87a199eaf23/MAINTAINERS.md#release-process also update the chart as part of the release process, in case that the CRD as changed

[swoehrl-mw]

Hi @IshaGirdhar.
IMO this is the wrong approach here.

What would be beneficial is adding a cluster spec to the helm chart of the operator itself (hidden under a by default disabled value), for those who just want to install one cluster and don't want to deploy the operator and the cluster spec separately (for example the prometheus-operator does something similar where you get the operator + 1 prometheus stack by installing the chart and can always create additional stacks by deploying additional CRs).

But a separate helm chart with only a cluster spec is IMO not very helpful. If someone is deploying several opensearch clusters (and is doing this as part of some larger deployment) then they most likely already have either mechanisms for deploying kubernetes yamls (so they don't need the overhead of the helm chart) or have their own custom helm chart around that combines such single yamls into one deployment (my personally preferred approach).

So IMO the helm chart as you have written it is not something we should add to the operator offering.

[IshaGirdhar]

Hi @IshaGirdhar. IMO this is the wrong approach here.

What would be beneficial is adding a cluster spec to the helm chart of the operator itself (hidden under a by default disabled value), for those who just want to install one cluster and don't want to deploy the operator and the cluster spec separately (for example the prometheus-operator does something similar where you get the operator + 1 prometheus stack by installing the chart and can always create additional stacks by deploying additional CRs).

But a separate helm chart with only a cluster spec is IMO not very helpful. If someone is deploying several opensearch clusters (and is doing this as part of some larger deployment) then they most likely already have either mechanisms for deploying kubernetes yamls (so they don't need the overhead of the helm chart) or have their own custom helm chart around that combines such single yamls into one deployment (my personally preferred approach).

So IMO the helm chart as you have written it is not something we should add to the operator offering.

@swoehrl-mw What you say makes sense to me and that also supports our use case as well. The only reason for taking this approach was to support multiple clusters using helm. Sure I can modify my existing PR or open a new PR for what you proposed.

[IshaGirdhar]

@swoehrl-mw On second thoughts, this solution seems to be fine as well, as this supports what the operator supports(multiple clusters), doesn't have any technical challenges though yeah users may have their own automated ways to create multiple clusters but that doesn't stop them from using Helm to do the same.

[idanl21]

Hey @swoehrl-mw @prudhvigodithi
What are you saying about that PR ?

[swoehrl-mw]

Left some specific comments.
Also:

• Extend the workflows to release this chart (and update the versions)
• Extend the developer guide that additions to the CRDs must also be reflected in this chart so they stay in sync
• Extend the description in MAINTAINERS.md
• Extend the functionaltests so that they also try to install this chart to see if it is valid

@idanl21 Truthfully I'm still not convinced this chart is a good idea. I believe most people that want to do everything with helm and have a proper deployment structure and process will rather either build a custom chart or have such a chart already where they can include the CR. But if other people see value in this I'll not gonna block it.

[IshaGirdhar]

@swoehrl-mw Please check. I have addresses all review comments.

[swoehrl-mw]

Two nitpicks, looks good otherwise.