High/Low Prio Load Balancer

Transparent jsonrpc/http proxy and load balancer with high and low priority queue and retries.

In the current setup, all requests in the high priority queue will be proxied before any of the low-prio queue.

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App structure and request flow:

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Getting started

Docker images are available at https://hub.docker.com/r/flashbots/prio-load-balancer

Run the program

# Run with a mock execution backend and debug output
go run . -mock-node

# add request for low-prio queue
curl -d '{"jsonrpc":"2.0","method":"eth_callBundle","params":[],"id":1}' localhost:8080

# add request for high-prio queue
curl -H 'X-High-Priority' -d '{"jsonrpc":"2.0","method":"eth_callBundle","params":[],"id":1}' localhost:8080

# Get execution nodes
curl localhost:8080/nodes

# Add a execution node
curl -d '{"uri":"http://foo"}' localhost:8080/nodes

# Remove a execution node
curl -X DELETE -d '{"uri":"http://foo"}' localhost:8080/nodes
curl -X DELETE -d '{"uri":"http://localhost:8095"}' localhost:8080/nodes

Note: there's a bunch of constants that can be configured with env vars in server/consts.go.

Node selection

• Redis is used as source of truth for which execution nodes to use.
• If you restart with a different set of configured nodes (i.e. in env vars), the previous nodes will still be in Redis and still be used by the load balancer.
• See the commands in the readme above on how to get the nodes it uses, and how to add/remove nodes.

Test, lint, build

# lint & staticcheck (staticcheck.io)
make lint

# run tests
make test

# test coverage
make cover
make cover-html

# build
make build

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Queue Benchmarks

goarch: amd64
pkg: github.com/flashbots/prio-load-balancer/server
cpu: Intel(R) Core(TM) i9-8950HK CPU @ 2.90GHz

1 worker, 10k tasks:
BenchmarkPrioQueue-12    	    	    2338	    492219 ns/op	  298109 B/op	      34 allocs/op

5 workers, 10k tasks:
BenchmarkPrioQueueMultiReader-12    	    2690	    596315 ns/op	  292507 B/op	      50 allocs/op

5 workers, 100k tasks:
BenchmarkPrioQueueMultiReader-12    	     261	   4637403 ns/op	 4245243 B/op	      66 allocs/op

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Todo

Possibly

• Currently it works for jsonrpc requests. To make it work for any http request it would need to also proxy the headers and the URL.
• Queue rules: i.e. for 10 high-prio items, process 1 low-prio item
• Configurable redis prefix, to allow multiple sim-lbs per redis instance
• Execution-node health checks (currently not implemented)
• DoS protection / rate limiting (i.e. per IP)

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Maintainers

• @metachris

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License

The code in this project is free software under the MIT License.