This QuickStart will guide you through using the Forte Rules Engine in a local anvil devlopment environment utilizing the Forte Rules Engine SDK. This guide will go over:

  1. Environment prerequisites
  2. Building
  3. Starting a local Anvil instance
  4. Configuring your environment
  5. Creating a sample policy in the Rules Engine
  6. Configuring and Deploying the ExampleContract
  7. Setting the Rules Engine Address in the ExampleContract
  8. Applying the policy to the sample contract and verifying functionality

NOTE: This guide was developed in a MacOS environment, some modification may be necessary to suit a Linux/Windows environment.

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1. Environment dependencies

This guide assumes the following tools are installed and configured correctly. Please see each tool’s installation instructions for more details:

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2. Building

Create a copy of our template repository in your own github account by navigating here: https://github.com/thrackle-io/fre-quickstart and clicking the “Use this template” button on GitHub.

Next, clone the freshly created repository to your local machine:

git clone https://github.com/<YOUR_GITHUB_USERNAME>/fre-quickstart

If you named the repository something different than fre-quickstart, use that name in the clone command instead.

Navigate to the repository in your local shell. To build the repository, run the following commands:

npm install
forge install

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3. Starting a local Anvil chain

An Anvil dumpState file is provided with a pre-deployed Rules Engine instance. Start the local Anvil instance in a terminal window with the following command:

anvil --load-state anvilState.json

Listening on 127.0.0.1:8545 should be the last thing displayed if the state file was successfuly loaded. Leave this Anvil instance running in this terminal for the rest of the quickstart. It may be restarted at any time but restarting will lose any on-chain progress you’ve made during the quickstart.

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4. Configure your local environment

The .env.sample environment file contains the following configurations:

RPC_URL - The RPC endpoint to utilize when interacting with an EVM chain. This is defaulted to a local anvil RPC that is enabled when starting anvil. This can be updated to point to any testnet/mainnet RPC if desired. See anvil for more details.

# local anvil RPC, change this if you're deploying to a network
RPC_URL=http://127.0.0.1:8545

PRIV_KEY - The private key for the account that will be performing the actions outlined in this guide. This is defaulted to a widely known default Anvil account for the purposes of this guide. It is recommended that this be updated prior to deploying to any testnet or mainnet.

# local anvil account private key, change to your deployer wallet key when using a live network
PRIV_KEY=0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80

RULES_ENGINE_ADDRESS - The address of the deployed Rules Engine instance on the target RPC’s chain. This is defaulted to the address where the Rules Engine was deployed in the anvilState.json file. For additional chain locations, please see the Forte Rules Engine docs.

# address of the rules engine within the anvil state file
RULES_ENGINE_ADDRESS=0x0165878A594ca255338adfa4d48449f69242Eb8F

Once you are satisfied with the above configurations open a new terminal window (separate from the running anvil instance) and ensure the variables are exported in your local shell with the following command:

cp .env.sample .env
source .env

The SDK utilizes the Rules Engine address and private key values from the environment file. This requires that you name your file .env, which enables the SDK to access the values.

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5. Create the sample policy in the Rules Engine

To use the Rules engine, we must first create a policy. A default policy has been created within the policy.json that is tailored to work with the ExampleContract. To create this policy in the Rules Engine, run the following command:

npx tsx index.ts setupPolicy policy.json

Note the returned Policy Id, for this example the Policy Id should be 1, and create a local environment variable to store this Id for uses in subsequent commands:

export POLICY_ID=1

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6. Configure and Deploy the ExampleContract

The ExampleContract is a blank contract that conforms to a standard ERC20 interface transfer() function. The file does not store any data. The integration of the Rules Engine occurs by adding a modifier. This modifier may be generated by passing the policy information, destination modifier filename, and the example contract to the SDK. The SDK will process the policy, generate modifiers within the specified modifier file for each function within the Policy, and inject these newly generated modifiers within the supplied contract. This has been scripted in the index.ts with the following command:

npx tsx index.ts injectModifiers policy.json src/RulesEngineIntegration.sol src/ExampleContract.sol

After running this command, it will inject the beforeXXX() modifier within the function specified within the policy.json file. Verify the contract compiles and deploy the contract with the following commands:

forge script script/ExampleContract.s.sol --ffi --broadcast -vvv --non-interactive --rpc-url $RPC_URL --private-key $PRIV_KEY

Note the contract address, and export the address in your local terminal for subsequent testing.

export CONTRACT_ADDRESS=<0xYourContractAddress>

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7. Set Rules Engine Address in the ExampleContract

The ExampleContract extends the RulesEngineClient to encapsulate storing the Rules Engine address and checks. It is recommended that all calling contracts extend this contract. This ensures calling contracts will only invoke the Rules Engine checks if the Rules Engine Address is specified. Set the Rules Engine Address in the ExampleContract via the following command:

cast send $CONTRACT_ADDRESS "setRulesEngineAddress(address)" $RULES_ENGINE_ADDRESS --rpc-url $RPC_URL --private-key $PRIV_KEY

To verify the address was set correct, the following commmand should return the same Rules Engine Address:

cast call $CONTRACT_ADDRESS "rulesEngineAddress()(address)" --rpc-url $RPC_URL

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8. Apply the Policy and Test

npx tsx index.ts applyPolicy $POLICY_ID $CONTRACT_ADDRESS

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Test Success Condition

cast send $CONTRACT_ADDRESS "transfer(address,uint256)" 0x70997970C51812dc3A010C7d01b50e0d17dc79C8 10001 --rpc-url $RPC_URL --private-key $PRIV_KEY

You should receive a revert with the text “Passed Test”

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Test Failure Condition

cast send $CONTRACT_ADDRESS "transfer(address,uint256)" 0x70997970C51812dc3A010C7d01b50e0d17dc79C8 9999 --rpc-url $RPC_URL --private-key $PRIV_KEY

You should receive a revert with the text “Failed Test”