Support Hash-Based Routing

[hoffmaen]

This Pull-Request adds support for hash-based routing to Cloud Controller.

Summary: The routes model is enhanced as follows:

• hash is added as a valid loadbalancing option
• hash_header is added as a per-route option. The option is mandatory when loadbalancing=hash
• hash_balance is added as a per-route option. The option is optional when loadbalancing=hash

Validation of these options is added when creating and updating both via API and via manifest. When hash_balance is provided as an option, its value must be a float or a string representing a float.

The options are still stored as a raw JSON string in the routes table. The value for hash_balance is always stored as a string inside the JSON for consistency.

Logic is introduced to remove hash_balance and hash_header when switching from hash to another load-balancing algorithm. Incremental updates on per-route options are allowed, e.g. only updating hash_header or hash_balance while keeping other previously set per-route options is possible.

Links:

• capi-release implementation issue

• routing-release Pull-Request for hash-based routing support

• RFC-0042

• [x] I have reviewed the contributing guide

• [x] I have viewed, signed, and submitted the Contributor License Agreement

• [x] I have made this pull request to the main branch

• [x] I have run all the unit tests using bundle exec rake

• [ ] I have run CF Acceptance Tests