Switchboard On-Demand: Lottery Example

This example demonstrates how to build a decentralized lottery using Switchboard's On-Demand Randomness functionality.

Getting Started

Welcome to the Switchboard Lottery example. This project showcases how to build a secure and fair lottery system using Switchboard's on-demand randomness solution on Solana.

To read more about the security guarantees that Switchboard Randomness On-Demand provides, please see: https://docs.switchboard.xyz/docs/switchboard/switchboard-randomness

PLEASE ENSURE YOU USE ANCHOR VERSION 0.30.0

Configure the anchor.toml file to point to your solana wallet and the Solana cluster of your choice - Devnet, Mainnet, etc.

Then, build the program:

anchor build

After building, take note of your program address and insert it in your program lib.rs file: Note: You can view your program address with anchor keys list

declare_id!("[YOUR_PROGRAM_ADDRESS]");

Rebuild your program and deploy:

anchor build
anchor deploy
anchor idl init --filepath target/idl/lottery.json YOUR_PROGRAM_ADDRESS

Note: You may need to use anchor idl upgrade --filepath target/idl/lottery.json YOUR_PROGRAM_ADDRESS if you are upgrading the program.

About the Lottery

This example implements a decentralized lottery with the following features:

• Multiple concurrent lotteries identified by unique IDs
• Configurable entry fees and end times
• Fair winner selection using Switchboard's verifiable randomness
• 90% prize pool distribution to winner, 10% to developer
• Automatic prize claiming system

Test Setup & Execution

Prerequisites

1. Install Solana Tool Suite (1.17.0 or later)
2. Install Anchor (0.30.0):

   cargo install --git https://github.com/coral-xyz/anchor avm --locked --force
   avm install 0.30.1
   avm use 0.30.1

3. Install Node.js
4. Configure Solana CLI for devnet:

   solana config set --url devnet

5. Create a test wallet and fund it:

   solana-keygen new -o test-wallet.json
   solana airdrop 2 test-wallet.json --url devnet

6. Set wallet=/path/to/test-wallet.json in Anchor.toml

Note: You can get the cli config by using the solana config get command.

Setup Steps

1. Clone the repository:

   git clone <repository-url>
   cd lottery

2. Build the program:

   anchor clean  # Clean any existing build artifacts
   anchor build

3. Get your program ID:

   anchor keys list

4. Update program ID in two places:

   • In programs/lottery/src/lib.rs:

     declare_id!("YOUR_PROGRAM_ID");

   • In Anchor.toml:

     [programs.devnet]
     lottery = "YOUR_PROGRAM_ID"

5. Build and deploy:

   anchor build
   anchor deploy

6. Initialize IDL:

   anchor idl init --filepath target/idl/lottery.json YOUR_PROGRAM_ID

Running Tests

1. Ensure you have sufficient SOL for testing:

   solana balance  # Should show at least 1 SOL

2. Run the test suite:

   anchor test

Troubleshooting Common Test Issues

• If tests fail with account errors:

  anchor clean
  anchor build
  anchor deploy

• If you see program ID mismatches:

  1. Get the correct program ID:

     anchor keys list

  2. Update both locations mentioned in Setup Step 5
  3. Rebuild and redeploy

• If you get IDL errors:

  anchor idl upgrade --filepath target/idl/lottery.json YOUR_PROGRAM_ID

Note: Always ensure you're on devnet and have sufficient SOL before running tests.

Debugging

Common Issues

1. Account Size Errors / Program Changes When making significant changes to the program's state or instruction parameters, you may need to:

   cargo clean
   anchor build
   anchor keys list
   # Update program ID in lib.rs and Anchor.toml
   anchor build (again for safe measure)
   anchor deploy

   This is necessary when:

   • Adding/removing fields in account structs
   • Changing account sizes
   • Modifying instruction parameters
   • Getting program/account size mismatch errors
   • Encountering IDL inconsistencies

2. Program ID Mismatches If you see errors related to program IDs:

   anchor keys list  # View your program address
   # Update declare_id!() in lib.rs
   # Update Anchor.toml
   anchor build
   anchor deploy

3. IDL Updates After making program changes:

   anchor idl init --filepath target/idl/lottery.json YOUR_PROGRAM_ADDRESS
   # Or if upgrading:
   anchor idl upgrade --filepath target/idl/lottery.json YOUR_PROGRAM_ADDRESS

Build System Cleaning

anchor clean vs cargo clean:

• anchor clean: Cleans Anchor-specific build artifacts including:

  • Program keypairs
  • IDL files
  • Program deployment info
  • TypeScript bindings
  • All Cargo build artifacts

• cargo clean: Only cleans Rust/Cargo build artifacts:

  • Compiled program files
  • Dependencies
  • Does not touch Anchor-specific files

Use anchor clean when you need a complete reset of your program's build state, especially after structural changes. Use cargo clean when you only need to rebuild the Rust code.

RPC Config

solana config set --url devnet

solana config set --url devnet

RPC Providers:

• https://shyft.to
• https://quicknode.com/
• https://helius.dev/