Add support for creating regex- and subnet-based ReadFrom instances from a single string

[wilkinsona]

Feature Request

Spring Boot would like to be able to offer support for configuring Lettuce's ReadFrom setting using an application property. This is straightforward for the many ReadFrom constants that are supported by ReadFrom#valueOf but harder for the regex and subnet variants. We'd like to make this easier by enhancing valueOf to support regex and subnet as well.

Is your feature request related to a problem? Please describe

Please see spring-projects/spring-boot#42588 for background and a description of the problem we're currently facing with trying to configure the regex and subnet variants with a single property.

Describe the solution you'd like

Our proposal is to enhance valueOf with support for a special syntax that allow the caller to indicate that a regex or subnet instance should be created and to provide the patterns or CIDR notations at the same time. The variant would be indicated by a prefix such as regex: or subnet: with the remainder of the string being the value. For example, "regex:.*region-1.*" or "subnet:192.168.0.0/16". Comma-separated values could be supported as well such as "subnet:192.168.0.0/16,2001:db8:abcd:0000::/52".

Supporting an order-sensitive regex hasn't really been considered yet. Perhaps an order-sensitive-regex would be the cleanest option?

Describe alternatives you've considered

We've considered defining this syntax in Spring Boot and pre-processing the value before calling ReadFrom#pattern or ReadFrom#subnet as appropriate. We concluded that it would be better for Lettuce itself to support the syntax as it broadens the benefit and also means that Spring Boot won't be an odd-on-out with a feature that may clash with a future change in Lettuce.

Teachability, Documentation, Adoption, Migration Strategy

Users will be able to call ReadFrom#valueOf and create any of the supported variants if they pass in an appropriately formatted string. No migration would be required as I would expect the existing subnet and regex methods to remain for those who prefer not to use a "magic" string.

[nosan]

If you need assistance with this issue, I can create a PR. The implementation is already completed in my branch, but I'm waiting for the team's decision on whether to move forward with this enhancement.

[tishun]

If you need assistance with this issue, I can create a PR. The implementation is already completed in my branch, but I'm waiting for the team's decision on whether to move forward with this enhancement.

PRs are welcome, especially if you already have a suggestion.

[nosan]

Would you consider adding support for the following formats as well?
ANY_REPLICA, any-replica?

[nosan]

PR has been created.

[tishun]

Would you consider adding support for the following formats as well? ANY_REPLICA, any-replica?

Let's discuss this in the PR