Read-only RPC server #742
Description
Allow configuring a read-only RPC server which only connects to the store and not to the block-producer.
In other words in this mode the RPC server would not allow for transaction submissions. It can only be used to query the chain state.
Original comment here:
Not for this PR, but would should probably make block_producer parameter optional. This would allow spinning up RPC components which are connected only to the store and can do pretty much everything except for accepting transactions. Let's create an issue for this.
Implementation considerations:
- a separate RPC constructor vs optional block-producer URL
- how configuration would work
- trace events and telemetry to indicate the mode
- gRPC API should indicate this via some appropriate error for tx submissions