Route across your own RPC providers

Lasso RPC Core is an open-source EVM JSON-RPC proxy for a provider pool you control. It selects eligible upstreams from live health and method-specific measurements. Replay-safe reads can fail over within the request deadline and dispatch budget. Provider quotas and method coverage still limit the pool. For a hosted pool, use Lasso Cloud custom profiles. This guide runs the released Core container locally.

Start the container

Install the selected release using the commands in Docker deployment. Confirm http://localhost:4000/api/health responds, then make an upstream-backed request from the quickstart. The health check alone does not prove that an RPC provider is reachable.

Add your providers

Follow Docker deployment: custom profiles and credentials to mount a profiles/ directory. Keep its valid public.yml. Save the following as profiles/my-app.yml. Replace every environment variable with a credential-bearing URL from a provider or node you control. Each chain needs providers that actually serve that chain.

---
name: My App
slug: my-app
---
chains:
  ethereum:
    chain_id: 1
    providers:
      - id: eth_a
        url: ${ETH_RPC_A}
      - id: eth_b
        url: ${ETH_RPC_B}
  base:
    chain_id: 8453
    providers:
      - id: base_a
        url: ${BASE_RPC_A}
      - id: base_b
        url: ${BASE_RPC_B}
  arbitrum:
    chain_id: 42161
    providers:
      - id: arb_a
        url: ${ARB_RPC_A}
      - id: arb_b
        url: ${ARB_RPC_B}

Store the variables in the private .env file used by Compose. Do not commit provider credentials. Unresolved variables reject the configuration. Validate chain identity and the methods your app needs against each upstream; a second configured URL does not prove an independent failure domain. See provider configuration for declared capabilities and provider selection for eligibility. After adding the mounted file or changing .env, recreate the container:

docker compose up -d --force-recreate --wait

For later YAML-only edits, use the configuration reload. Check its result before shifting application traffic.

Exercise each route

Send an upstream-backed read through each chain. fastest uses qualified recent latency evidence for the requested method; the default route is load-balanced. Neither strategy promises that one provider always wins.

for chain in ethereum base arbitrum; do
  curl --fail-with-body --silent --show-error \
    "http://localhost:4000/rpc/profile/my-app/fastest/$chain?include_meta=body" \
    -H 'Content-Type: application/json' \
    -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'
done

Check the response result and lasso_meta for each chain. The metadata identifies selection candidates, recorded attempts, and the executed channel when available. A candidate is not proof of a dispatch. See request metadata for the released field contract and a failover example.

Test a provider failure

In a non-production trial, interrupt one upstream that you control while you send replay-safe reads through the profile. Compare successful responses, errors, p95/p99 latency, head freshness, and attempted_channels before and during the fault. Then restore it and check recovery. Lasso can try another eligible provider within its deadline and dispatch budget; it cannot recover if the remaining pool is unavailable, over quota, or does not support the request. Signed transactions and other unsafe work have different replay rules in the method contract. Keep the original provider route available for rollback while you compare the same application traffic. Before exposing the container to clients, apply the network and authentication guidance: Core does not provide inbound API-key authentication or per-client RPC quotas.

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Core Concepts

Configuration

Deployment

Observability

Advanced

Route across your own RPC providers

Start the container

Add your providers

Exercise each route

Test a provider failure

​Start the container

​Add your providers

​Exercise each route

​Test a provider failure

Start the container

Add your providers

Exercise each route

Test a provider failure