Lite RPC For Solana Blockchain

Submitting a transaction to be executed on the solana blockchain, requires the client to identify the next few leaders based on the leader schedule, look up their peering information in gossip and connect to them via the quic protocol. In order to simplify the process so it can be triggered from a web browser, most applications run full validators that forward the transactions according to the protocol on behalf of the web browser. Running full solana validators is incredibly resource intensive (>256GB RAM), the goal of this project would be to create a specialized micro-service that allows to deploy this logic quickly and allows horizontal scalability with commodity vms. Optionally the Lite RCP micro-services can be configured to send the transactions to a complementary QUIC forward proxy instead of the solana tpu (details).

Confirmation strategies

1. Subscribe to new blocks using websockets (deprecated)
2. Polling blocks over RPC.(Current)
3. Subscribe blocks over gRPC. (Current)
4. Listening to gossip protocol. (Future roadmap)

Executing

run using

$ cargo run --release

to know about command line options

$ cargo run --release -- --help

Test and Bench

Make sure both solana-validator and lite-rpc is running

test

$ cargo test

bench

$ cd bench and cargo run --release

Find a new file named metrics.csv in the project root.

Deployment

Environment Variables

Thank you for providing the default values. Here's the updated table with the default values for the environment variables based on the additional information:

Environment Variable	Purpose	Required?	Default Value
RPC_ADDR	Address for the RPC node	Replaces default if set	http://0.0.0.0:8899 (from DEFAULT_RPC_ADDR)
WS_ADDR	WebSocket address for the RPC node	Replaces default if set	ws://0.0.0.0:8900 (from DEFAULT_WS_ADDR)
LITE_RPC_HTTP_ADDR	HTTP address for the lite RPC node	Replaces default if set	http://0.0.0.0:8890 (from DEFAULT_LITE_RPC_ADDR)
LITE_RPC_WS_ADDR	WebSocket address for the lite RPC node	Replaces default if set	[::]:8891 (from Config::default_lite_rpc_ws_addr)
FANOUT_SIZE	Configuration for the fanout size	Replaces default if set	18 (from DEFAULT_FANOUT_SIZE)
IDENTITY	Identity keypair	Optional, replaces default if set	None
PROMETHEUS_ADDR	Address for Prometheus monitoring	Replaces default if set	None specified in provided defaults
MAX_RETRIES	Maximum number of retries per transaction	Replaces default if set	40 (from MAX_RETRIES)
RETRY_TIMEOUT	Timeout for transaction retries in seconds	Replaces default if set	3 (from DEFAULT_RETRY_TIMEOUT)
QUIC_PROXY_ADDR	Address for QUIC proxy	Optional	None
USE_GRPC	Flag to enable or disable gRPC	Enables gRPC if set	false
GRPC_ADDR GRPC_ADDR2 GRPC_ADDR3 GRPC_ADDR4	gRPC address(es); will be multiplexed	Replaces default if set	http://127.0.0.0:10000 (from DEFAULT_GRPC_ADDR)
GRPC_X_TOKEN GRPC_X_TOKEN2 GRPC_X_TOKEN3 GRPC_X_TOKEN4	Token for gRPC authentication	Optional	None
PG_*	Various environment variables for Postgres configuration	Depends on Postgres usage	Based on PostgresSessionConfig::new_from_env()

Postgres

lite-rpc implements an optional postgres service that can write to postgres database tables as defined in ./migrations. This can be enabled by either setting the environment variable PG_ENABLED to true or by passing the -p option when launching the executable. If postgres is enabled then the optional environment variables shown above must be set.

Metrics

Various Prometheus metrics are exposed on localhost:9091/metrics which can be used to monitor the health of the application in production.

Deployment on fly.io

While lite-rpc can be deployed on any cloud infrastructure, it has been tested extensively on https://fly.io. An example configuration has been provided in fly.toml. We recommend a dedicated-cpu-2x VM with at least 4GB RAM.

The app listens by default on ports 8890 and 8891 for HTTP and Websockets respectively. Since only a subset of RPC methods are implemented, we recommend serving unimplemented methods from a full RPC node using a reverse proxy such as HAProxy or Kong. Alternatively, you can connect directly to lite-rpc using a web3.js Connection object that is only used for sending and confirming transactions.

Troubleshooting: if you encounter issues with QUIC sendmsg check this - you might need to explicitly disable GSO (Generic Segmenatin Offload) see DISABLE_GSO=true

Example

fly apps create my-lite-rpc
fly secrets set -a my-lite-rpc RPC_URL=... WS_URL=...   # See above table for env options
fly scale vm dedicated-cpu-2x --memory 4096 -a my-lite-rpc
fly deploy -c cd/lite-rpc.toml -a my-lite-rpc --remote-only # To just launch lite-rpc
fly deploy -c cd/lite-rpc.toml -a my-lite-rpc --remote-only # To launch lite-rpc with proxy mode

License & Copyright

Copyright (c) 2022 Blockworks Foundation

Licensed under the AGPL-3.0 license