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Lasso is configured via YAML profile files located in config/profiles/. Each profile defines chains, providers, routing policies, and rate limits. Multiple profiles enable isolated configurations for different environments or tenants.

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Profile System

Profiles are the core configuration unit in Lasso. Each profile:
  • Defines which blockchain networks (chains) to support
  • Specifies RPC providers for each chain
  • Configures routing behavior, health monitoring, and WebSocket subscriptions
  • Sets rate limits and capacity controls
  • Can be accessed via unique URL paths

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Profile File Structure

Each profile is a YAML file with two sections separated by document markers (---): 
# config/profiles/<slug>.yml

# --- Frontmatter: Profile metadata ---
---
name: "My Profile"
slug: "my-profile"
rps_limit: 100
burst_limit: 500
---

# --- Body: Chain configurations ---
chains:
  ethereum:
    chain_id: 1
    providers:
      - id: "my_provider"
        url: "https://..."
Frontmatter contains profile-level settings like name, URL slug, and rate limits. Body defines chain configurations with providers, monitoring settings, and routing parameters.

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URL Structure

Profiles are accessed via URL paths: 
# Default profile
POST /rpc/ethereum

# Named profile
POST /rpc/profile/production/ethereum

# Strategy override
POST /rpc/fastest/ethereum

# Profile + strategy
POST /rpc/profile/production/fastest/ethereum

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Configuration Hierarchy

Lasso’s configuration follows this hierarchy:
  1. Application Level - Runtime environment variables and system defaults
  2. Profile Level - Frontmatter settings (rate limits, metadata)
  3. Chain Level - Per-chain configuration (monitoring, selection, WebSocket)
  4. Provider Level - Individual provider settings (URLs, capabilities, priority)

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Multiple Profiles

Create separate profiles for different use cases: 
config/profiles/
├── default.yml      # Free public providers
├── production.yml   # BYOK + own nodes
└── staging.yml      # Subset for testing
Benefits:
  • Environment isolation - Separate configs for dev, staging, production
  • Tenant segmentation - Different provider sets per customer
  • A/B testing - Compare provider performance across profiles
  • Cost optimization - Route low-priority traffic to free providers

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Configuration Best Practices

The included default.yml profile contains battle-tested public providers for major chains. Use it as a reference or starting point.
Profile slugs appear in URLs. Choose descriptive, URL-safe names: production, high-priority, customer-acme.
Configure rps_limit and burst_limit based on expected traffic patterns. Start conservative and increase as needed.
Lasso validates all profiles at startup and crashes on errors (missing required fields, unresolved environment variables). This prevents runtime surprises.
Use YAML comments to explain why providers are included, their known limitations, and any special configuration.

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Next Steps

Profile Configuration

Learn about frontmatter fields and chain configuration

Provider Setup

Configure providers, API keys, and capabilities

Environment Variables

Reference for all runtime configuration options

Capabilities

Define provider limits and error handling rules