The vector-search client in ScyllaDB limits itself to doing one DNS
lookup per 5 seconds. However, when the configuration changes to point
to a different host, the DNS lookup should happen immediately, and
this patch makes it do that.
Before this patch,
test/cqlpy/run test_vector_search_with_vector_store_mock.py
Takes a whopping 34 seconds, more than 4 seconds per test!
The problem is that each test creates a new mock vector-store server
and reconfigures Scylla, and when reconfiguring Scylla nothing happens
until the 5-second clock runs out.
After this patch, the same test run is down to 5 seconds.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
The `vector_store_client_uri_update_to_invalid` test was flaky because
it performed real DNS lookups, making it dependent on the network
environment.
This commit replaces the live DNS queries with a mock to make the test
hermetic and prevent intermittent failures.
`vector_search_metrics_test` test did not call configure{vs},
as a consequence the test did real DNS queries, which made the test
flaky.
The refreshes counter increment has been moved before the call to the resolver.
In tests, the resolver is mocked leading to lack of increments in production code.
Without this change, there is no way to test DNS counter increments.
The change also simplifies the test making it more readable.
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 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>
