This commit adds a dns refresh counting metric
to the vector_store service. We would like to
track it to make sure that the networking is working
correctly.
The vector store client now supports a comma-separated list of URIs in
the `vector_store_primary_uri` configuration option.
It uses the vector store nodes from these URIs for load balancing and high
availability, querying the next node if the current one fails.
The `vector_store_client::port()` and `vector_store_client::host()` methods
were only used in the test code.
Moreover, these tests are no longer needed, as the proper parsing of the
URI is already tested in other tests that perform requests to the
vector store server mock.
This change introduces a load balancing mechanism for the vector store client.
The client can now distribute requests across multiple vector store nodes.
The distribution mechanism performs random selection of nodes for each request.
Rename `HTTP_REQUEST_RETRIES` to `ANN_RETRIES` in `vector_store_client`,
as it now applies to all vector store nodes, not just HTTP requests.
Also, remove an unused test setter function.
The DNS resolution logic now processes all IP addresses returned in a DNS
response, not just the primary one.
The client will iterate through the list of resolved IPs, attempting to
query the next one if a request fails. This improves high availability
by allowing the client to query other available nodes if one is down.
The DNS resolution logic and its background task are moved out of the
`vector_store_client` and into a new, dedicated class `vector_search::dns`.
This refactoring is the first step towards supporting DNS hostnames
that resolve to multiple IP addresses.
Signed-off-by: Karol Nowacki <karol.nowacki@scylladb.com>
Vector search related implementation moved to a new module vector_search.
As the vector search functionality is going to be extended, it is
better to keep it in a separate module.
