OpenSearch offers a vendor-agnostic toolset you can use to build secure, high-performance, cost-efficient applications. From a tracing perspective, OpenSearch acts as both a data store and a visualization tool for traces via its Trace Analytics tool.
Tracetest leverages the observability provided by the traces stored in OpenSearch to quickly build tests across your distributed architecture. Tests created in Tracetest can verify not only against the response from calls to your system, but it can also verify all the underlying processes that are exposed in the spans collected in the trace that is created as a result of the triggering of the test. This enables a distributed test to be created to verify the entire flow across multiple microservices.
Tracetest pulls traces from OpenSearch when running tests. You use traces as assertions to get complete insight into every part of the request transaction. You can configure your Tracetest server to communicate with your OpenSearch instance via the UI or via a CLI command.
OpenSearch Blog - Using OpenSearch as the traces storage for Tracetest