We should have one standard way of configuring localstack endpoint for all services. This diff standardizes the localstack config for blob-service.
I consider Tunnelbroker as state-of-the-art solution for localstack endpoint configuration.
TL;DR
cargo run -- --sandbox --localstack-url "http://localhost:4566"
-->
cargo run
The LOCALSTACK_ENDPOINT env variable is automatically provided by Nix so no need to specify --localstack-endpoint explicitly.