CacheDB compile

[Lammiwinks]

Hi Crazy-Max. First of all THANK YOU for an amazing image. This is the only docker image I could get working properly :).

QQ: Would you be able to include the cachedb option into a future release?

The Cache DB module must be configured in the module-config: "validator
cachedb iterator" directive and be compiled into the daemon with --en-
able-cachedb. If this module is enabled and configured, the specified
backend database works as a second level cache: When Unbound cannot
find an answer to a query in its built-in in-memory cache, it consults
the specified backend. If it finds a valid answer in the backend, Un-
bound uses it to respond to the query without performing iterative DNS
resolution. If Unbound cannot even find an answer in the backend, it
resolves the query as usual, and stores the answer in the backend.

The main reason for this is it allows you to keep a persistent DB that survives reboots / image updates and means you don’t have to rebuild it all again.

Thanks,

Lammi