[FEATURE] Support switch alias from source to target index in shrink action

[bowenlan-amzn]

Support switch alias from source to target index in shrink action

[Jakob3xD]

Would be really nice to see this.
I currently have two polices that shrink indices before they get moved to cold nodes and loosing the read alias when shrink them is a real pain, as I now have to copy my polices for each index and use the alias action to apply the read alias again.

[ikibo]

@bowenlan-amzn could I be assigned to this issue plz? THNX!

[ikibo]

A point to take into account :
When shrinking an index, there are two sources of aliases for the target-index:

• aliases from the shrink action in the policy
• aliases from the source index

Index alias is unique by name, and names of aliases may coincide in these two sources. In such a case, there is a collision, and priority will be given to the alias from the policy. Hence the target-index will possess an alias from the policy.

this is a natural decision, in such a way a client may override some properties of a source-index alias, and of course, add new aliases on demand.
if we follow this approach, we need to add this to the official doc for the correct release version, so that clients are aware, and are protected from undesired error/behaviour.

@bowenlan-amzn plz sign off if the above is good.

[bowenlan-amzn]

Yes, this idea looks good.
Doc is needed for this, and would you please add a new param switch_alias in shrink action and default to false. Thanks!

[hdhalter]

@bowenlan-amzn - can you please add this to the roadmap/tracker for 2.12? Thanks!

[bowenlan-amzn]

@hdhalter added to the unified project tracker, pls lemme know if it's not right way