Interstellar Risk mvp

This use case showcases how Chainlink Functions can be used to trigger a parametric insurance to offer payouts to clients, with Chainlink Functions being used to fetch data from 3 different weather APIs for temperature data.

Parametric Insurance offers payouts to clients based upon a trigger event. In the sample, a smart contract will offers payouts based on the temperature in New York City. If the temperature falls below 60 degrees Fahrenheit (you can define the different number) for three consecutive days, the insurance will pay the client with balances.

There is a smart contract called ParametricInsurance created for the use case, and clients can get payout if the predefined conditions in the smart contract are met.

In the ParametricInsurance, anyone can call function executeRequest(there is a limit that only one call per day) and send a request to Chainlink Functions. After the request event is detected by off-chain Chainlink node, the node will fetch the data and execute the computing logics defined in Parametric-insurance-example.js.

After results are calculated, the returned data will be passed through Chainlink Off-Chain Reporting mechanism(Chainlink OCR) to be aggregated. After the data aggregation, Chainlink functions will call function fulfillRequest and the client would be paid if predefined condition(three consecutive cold days in the use case) is met.

requirements

• node.js version 18

Instructions to run this sample

1. Clone this repository to your local machine by running git clone

2. Open this directory in your command line, then run npm install to install all dependencies.

3. Create a Github Token for secrets.

   To allow the starter kit(the repo is a fork from starter kit) to write gists on your behalf, create a github fine-grained personal access token. Please find more info about secrets here.

   Create a token based on following steps.

   • Visit Github tokens settings page.
   • Click on Generate new token.
   • Provide a name to your token and define the expiration date.
   • Under Account permissions, enable Read and write for Gists. Note: Do not enable additional settings.
   • Click on Generate token and copy your fine-grained personal access token.

4. Add encrypted environment variables to .env.enc

   • run npx env-enc set-pw to set a password for file .env-enc
   • run npx env-enc set to set required env var. Env vars includes rpc urls you plan to use, private key, exploerer API and weather APIs.

   you have a env-enc file like below:

MUMBAI_RPC_URL: ENCRYPTED|xxx
PRIVATE_KEY: ENCRYPTED|xxx
POLYGONSCAN_API_KEY: ENCRYPTED|xxx
GITHUB_API_TOKEN: ENCRYPTED|xxx
OPEN_WEATHER_API_KEY: ENCRYPTED|xxx
WORLD_WEATHER_API_KEY: ENCRYPTED|xxx
AMBEE_DATA_API_KEY: ENCRYPTED|xxx
CLIENT_ADDR: ENCRYPTED|xxx

• Get a free MUMBAI_RPC_URL from Alchemy.
• PRIVATE_KEY is your private key and KEEP IT IN SECRET in any case.
• Get a free POLYGONSCAN_API_KEY from Polygonscan.
• GITHUB_API_TOKEN is the token created in step 3.
• Get free OPEN_WEATHER_API_KEY from https://openweathermap.org/
• Get free WORLD_WEATHER_ONLINE_API_KEY from https://www.worldweatheronline.com/weather-api/
• Get a free AMBEE_DATA_API_KEY from https://api-dashboard.getambee.com/
• CLIENT_ADDR is the client who is supposed to receive payouts in the use case.

5. Deploy and verify the necessary contracts to an actual blockchain network by running: npx hardhat functions-deploy-client --network network_name_here --verify true

   Note: Make sure _ETHERSCAN_API_KEY_ or _POLYGONSCAN_API_KEY_ are set in file `.env-enc` if using `--verify true`, depending on which network is used.
   

6. Create, fund & authorize a new Functions billing subscription by running: npx hardhat functions-sub-create --network network_name_here --amount LINK_funding_amount_here --contract 0xDeployed_client_contract_address_here

   Note: Ensure your wallet has a sufficient LINK balance before running this command. Testnet LINK can be obtained at [faucets.chain.link](https://faucets.chain.link/).
   

7. Transfer some testnet native tokens to the contract with your wallet(metamask maybe).

8. Resend on-chain requests(at least twice) to make sure the value of variable consecutiveColdDays reach 3 by running the same command in last step:

   npx hardhat functions-request --network network_name_here --contract 0xDeployed_client_contract_address_here --subid subscription_id_number_here, replacing subscription_id_number_here with the subscription ID you received from the previous step

9. Check if the client(client address is defined in CLIENT_ADDR in .env-enc) receives the balance of insurance contract.

Tips

1. The default gaslimit for callback function is 100,000 and it may be insufficient. use --gaslimit 300000 when send request like command below:

npx hardhat functions-request --network {network name} --contract {your contract addr} --subid {your subid} --gaslimit 300000

---

Content below is general knowkedge from function-hardhat-starter-kit.

• Environment Variable Management
  • Environment Variable Management Commands
• Functions Command Glossary
  • Functions Commands
  • Functions Subscription Management Commands
• Request Configuration
  • JavaScript Code
    • Functions Library
  • Modifying Contracts
  • Simulating Requests
  • Off-chain Secrets
• Automation Integration

Environment Variable Management

This repo uses the NPM package @chainlink/env-enc for keeping environment variables such as wallet private keys, RPC URLs, and other secrets encrypted at rest. This reduces the risk of credential exposure by ensuring credentials are not visible in plaintext.

By default, all encrypted environment variables will be stored in a file named .env.enc in the root directory of this repo.

First, set the encryption password by running the command npx env-enc set-password. The password must be set at the beginning of each new session. If this password is lost, there will be no way to recover the encrypted environment variables.

Run the command npx env-enc set to set and save environment variables. These variables will be loaded into your environment when the config() method is called at the top of hardhat.config.js. Use npx env-enc view to view all currently saved environment variables. When pressing ENTER, the terminal will be cleared to prevent these values from remaining visible. Running npx env-enc remove VAR_NAME_HERE deletes the specified environment variable. The command npx env-enc remove-all deletes the entire saved environment variable file.

When running this command on a Windows machine, you may receive a security confirmation prompt. Enter r to proceed.

NOTE: When you finish each work session, close down your terminal to prevent your encryption password from becoming exposes if your machine is compromised.

Environment Variable Management Commands

The following commands accept an optional --path flag followed by a path to the desired encrypted environment variable file. If one does not exist, it will be created automatically by the npx env-enc set command.

The --path flag has no effect on the npx env-enc set-pw command as the password is stored as an ephemeral environment variable for the current terminal session.

Command	Description	Parameters
npx env-enc set-pw	Sets the password to encrypt and decrypt the environment variable file NOTE: On Windows, this command may show a security confirmation prompt
npx env-enc set	Sets and saves variables to the encrypted environment variable file
npx env-enc view	Shows all currently saved variables in the encrypted environment variable file
npx env-enc remove <name>	Removes a variable from the encrypted environment variable file	name: Variable name
npx env-enc remove-all	Deletes the encrypted environment variable file

Functions Command Glossary

The Functions and Functions subscription management commands commands can be executed in the following format: npx hardhat command_here --parameter1 parameter_1_value_here --parameter2 parameter_2_value_here

Example: npx hardhat functions-read --network mumbai --contract 0x787Fe00416140b37B026f3605c6C72d096110Bb8

Functions Commands

Command	Description	Parameters
compile	Compiles all smart contracts
functions-simulate	Simulates an end-to-end fulfillment locally for the FunctionsConsumer contract	gaslimit (optional): Maximum amount of gas that can be used to call fulfillRequest in the client contract (defaults to 100,000 & must be less than 300,000)
functions-deploy-client	Deploys the FunctionsConsumer contract	network: Name of blockchain network, verify (optional): Set to true to verify the deployed FunctionsConsumer contract (defaults to false)
functions-request	Initiates a request from a FunctionsConsumer client contract using data from Functions-request-config.js	network: Name of blockchain network, contract: Address of the client contract to call, subid: Billing subscription ID used to pay for the request, gaslimit (optional): Maximum amount of gas that can be used to call fulfillRequest in the client contract (defaults to 100,000 & must be less than 300,000), requestgas (optional): Gas limit for calling the executeRequest function (defaults to 1,500,000), simulate (optional): Flag indicating if simulation should be run before making an on-chain request (defaults to true)
functions-read	Reads the latest response (or error) returned to a FunctionsConsumer or AutomatedFunctionsConsumer client contract	network: Name of blockchain network, contract: Address of the client contract to read
functions-deploy-auto-client	Deploys the AutomatedFunctionsConsumer contract and sets the Functions request using data from Functions-request-config.js	network: Name of blockchain network, subid: Billing subscription ID used to pay for Functions requests, gaslimit (optional): Maximum amount of gas that can be used to call fulfillRequest in the client contract (defaults to 250000), interval (optional): Update interval in seconds for Chainlink Automation to call performUpkeep (defaults to 300), verify (optional): Set to true to verify the deployed AutomatedFunctionsConsumer contract (defaults to false), simulate (optional): Flag indicating if simulation should be run before making an on-chain request (defaults to true)
functions-check-upkeep	Checks if checkUpkeep returns true for an Automation compatible contract	network: Name of blockchain network, contract: Address of the contract to check, data (optional): Hex string representing bytes that are passed to the checkUpkeep function (defaults to empty bytes)
functions-perform-upkeep	Manually call performUpkeep in an Automation compatible contract	network: Name of blockchain network, contract: Address of the contract to call, data (optional): Hex string representing bytes that are passed to the performUpkeep function (defaults to empty bytes)
functions-set-auto-request	Updates the Functions request in deployed AutomatedFunctionsConsumer contract using data from Functions-request-config.js	network: Name of blockchain network, contract: Address of the contract to update, subid: Billing subscription ID used to pay for Functions requests, interval (optional): Update interval in seconds for Chainlink Automation to call performUpkeep (defaults to 300), gaslimit (optional): Maximum amount of gas that can be used to call fulfillRequest in the client contract (defaults to 250,000)
functions-set-oracle-addr	Updates the oracle address for a client contract using the FunctionsOracle address from network-config.js	network: Name of blockchain network, contract: Address of the client contract to update
functions-build-request	Creates a JSON file with Functions request parameters including encrypted secrets, using data from Functions-request-config.js	network: Name of blockchain network, output (optional): Output JSON file name (defaults to Functions-request.json), simulate (optional): Flag indicating if simulation should be run before building the request JSON file (defaults to true)
functions-build-offchain-secrets	Builds an off-chain secrets object that can be uploaded and referenced via URL	network: Name of blockchain network, output (optional): Output JSON file name (defaults to offchain-secrets.json)

Functions Subscription Management Commands

Command	Description	Parameters
functions-sub-create	Creates a new Functions billing subscription for Functions client contracts	network: Name of blockchain network, amount (optional): Initial amount used to fund the subscription in LINK (decimals are accepted), contract (optional): Address of the client contract to add to the subscription
functions-sub-info	Gets the Functions billing subscription balance, owner, and list of authorized client contract addresses	network: Name of blockchain network, subid: Subscription ID
functions-sub-fund	Funds a Functions billing subscription with LINK	network: Name of blockchain network, subid: Subscription ID, amount: Amount to fund subscription in LINK (decimals are accepted)
functions-sub-cancel	Cancels a Functions billing subscription and refunds the unused balance. Cancellation is only possible if there are no pending requests.	network: Name of blockchain network, subid: Subscription ID, refundaddress (optional): Address where the remaining subscription balance is sent (defaults to caller's address)
functions-sub-add	Authorizes a client contract to use the Functions billing subscription	network: Name of blockchain network, subid: Subscription ID, contract: Address of the client contract to authorize for billing
functions-sub-remove	Removes a client contract from a Functions billing subscription	network: Name of blockchain network, subid: Subscription ID, contract: Address of the client contract to remove from billing subscription
functions-sub-transfer	Request ownership of a Functions subscription be transferred to a new address	network: Name of blockchain network, subid: Subscription ID, newowner: Address of the new owner
functions-sub-accept	Accepts ownership of a Functions subscription after a transfer is requested	network: Name of blockchain network, subid: Subscription ID
functions-timeout-requests	Times out expired requests	network: Name of blockchain network, requestids: 1 or more request IDs to timeout separated by commas

Request Configuration

Chainlink Functions requests can be configured by modifying values in the requestConfig object found in the Functions-request-config.js file located in the root of this repository.

Setting Name	Description
codeLocation	This specifies where the JavaScript code for a request is located. Currently, only the Location.Inline option is supported (represented by the value 0). This means the JavaScript string is provided directly in the on-chain request instead of being referenced via a URL.
codeLanguage	This specifies the language of the source code which is executed in a request. Currently, only JavaScript is supported (represented by the value 0).
source	This is a string containing the source code which is executed in a request. This must be valid JavaScript code that returns a Buffer. See the JavaScript Code section for more details.
secrets	This is an object which contains secret values that are injected into the JavaScript source code and can be accessed using the name secrets. This object can only contain string values. This object will be automatically encrypted by the tooling using the DON public key before making request. Any DON member can use these secrets when processing a request.
perNodeSecrets	This is an array of secrets objects that enables the optional ability to assign a separate set of secrets for each node in the DON. DON members can only use the set of secrets which they have been assigned.
walletPrivateKey	This is the EVM private key. It is used to generate a signature for the encrypted secrets such that the secrets cannot be reused by an unauthorized 3rd party.
args	This is an array of strings which contains values that are injected into the JavaScript source code and can be accessed using the name args. This provides a convenient way to set modifiable parameters within a request.
expectedReturnType	This specifies the expected return type of a request. It has no on-chain impact, but is used by the CLI to decode the response bytes into the specified type. The options are uint256, int256, string, or Buffer.
secretsURLs	This is an array of URLs where encrypted secrets can be fetched when a request is executed. This array is converted into a space-separated string, encrypted using the DON public key, and used as the secrets parameter on-chain. If any URLs are provided, automatic Gist uploading will be disabled in favor of the provided URLs.

JavaScript Code

The JavaScript source code for a Functions request can use vanilla Node.js features, but cannot use any require statements or imported modules other than the built-in modules buffer, crypto, querystring, string_decoder, url, and util.

It must return a JavaScript Buffer which represents the response bytes that are sent back to the requesting contract. Encoding functions are provided in the Functions library. Additionally, the script must return in less than 10 seconds or it will be terminated and send back an error to the requesting contract.

In order to make HTTP requests, the source code must use the Functions.makeHttpRequest function from the exposed Functions library. Asynchronous code with top-level await statements is supported, as shown in the file API-request-example.js.

Functions Library

The Functions library is injected into the JavaScript source code and can be accessed using the name Functions.

In order to make HTTP requests, only the Functions.makeHttpRequest function can be used. All other methods of accessing the Internet are restricted. The function takes an object with the following parameters.

{
  url: String with the URL to which the request is sent,
  method (optional): String specifying the HTTP method to use which can be either 'GET', 'POST', 'PUT', 'DELETE', 'PATCH', 'HEAD', or 'OPTIONS' (defaults to 'GET'),
  headers (optional): Object with headers to use in the request,
  params (optional): Object with URL query parameters,
  data (optional): Object which represents the body sent with the request,
  timeout (optional): Number with the maximum request duration in ms (defaults to 5000 ms),
  responseType (optional): String specifying the expected response type which can be either 'json', 'arraybuffer', 'document', 'text' or 'stream' (defaults to 'json'),
}

The function returns a promise that resolves to either a success response object or an error response object.

A success response object will have the following parameters.

{
  error: false,
  data: Response data sent by the server,
  status: Number representing the response status,
  statusText: String representing the response status,
  headers: Object with response headers sent by the server,
}

An error response object will have the following parameters.

{
  error: true,
  message (may be undefined): String containing error message,
  code (may be undefined): String containing an error code,
  response (may be undefined): Object containing response sent from the server,
}

This library also exposes functions for encoding JavaScript values into Buffers which represent the bytes that a returned on-chain.

• Functions.encodeUint256 takes a positive JavaScript integer number and returns a Buffer of 32 bytes representing a uint256 type in Solidity.
• Functions.encodeInt256 takes a JavaScript integer number and returns a Buffer of 32 bytes representing a int256 type in Solidity.
• Functions.encodeString takes a JavaScript string and returns a Buffer representing a string type in Solidity.

Remember, it is not required to use these encoding functions. The JavaScript code must only return a Buffer which represents the bytes array that is returned on-chain.

Modifying Contracts

Client contracts which initiate a request and receive a fulfillment can be modified for specific use cases. The only requirements are that the contract successfully calls sendRequest in the FunctionsOracle contract and correctly implements their own handleOracleFulfillment function. At this time, the maximum amount of gas that handleOracleFulfillment can use is 300,000. See FunctionsClient.sol for details.

Simulating Requests

An end-to-end request initiation and fulfillment can be simulated for the default FunctionsConsumer contract using the functions-simulate command. This command will report the total estimated gas use. If the FunctionsConsumer client contract is modified, this task must also be modified to accomodate the changes. See tasks/Functions-client/simulate for details.

Note: The actual gas use on-chain can vary, so it is recommended to set a higher fulfillment gas limit when making a request to account for any differences.

Off-chain Secrets

Instead of using encrypted secrets written directly on the blockchain, encrypted secrets are hosted off-chain and be fetched by DON nodes via HTTP when a request is initiated. This allows encrypted secrets to be deleted when they are no longer in use. By default, the tooling automatically uploads secrets to private Github Gists and deletes them once a request is fulfilled unless the secrets are being used for an AutomatedFunctionsConsumer.sol contract. If integrating with Chainlink Automation, it is recommended to delete the secrets Gist manually once it is not longer in use. Note that if there are URL(s) provided for the secretsURLs parameter in Functions_request_config.js, automatic Gist uploading will be disabled in favor of using the provided URL(s).

Additionally, per-node secrets allow a separate set of secrets to be assigned to each node in the DON. Each node will not be able to decrypt the set of secrets belonging to another node. Optionally, a set of default secrets encrypted with the DON public key can be used as a fallback by any DON member who does not have a set of secrets assigned to them. This handles the case where a new member is added to the DON, but the assigned secrets have not yet been updated.

To use per-node assigned secrets, enter a list of secrets objects into perNodeSecrets in Functions-request-config.js. The number of objects in the array must correspond to the number of nodes in the DON. Default secrets can be entered into the secrets parameter of Functions-request-config.js. Each secrets object must have the same set of entries, but the values for each entry can be different (ie: [ { apiKey: '123' }, { apiKey: '456' }, ... ]). If the per-node secrets feature is not desired, perNodeSecrets can be left empty and a single set of secrets can be entered for secrets.

If you prefer to host secrets elsewhere instead of having them automatically uploaded to a Github Gist, generate the encrypted secrets JSON file by running the command npx hardhat functions-build-offchain-secrets --network network_name_here. This will output the file offchain-secrets.json which can be uploaded to any other hosting service that allows the JSON file to be fetched via URL. Once the JSON file is uploaded, enter the URL(s) where the JSON file is hosted into secretsURLs. Multiple URLs can be entered as a fallback in case any of the URLs are offline. Each URL should host the exact same JSON file. The tooling will automatically pack the secrets URL(s) into a space-separated string and encrypt the string using the DON public key so no 3rd party can view the URLs. Finally, this encrypted string of URLs is used in the secrets parameter when making an on-chain request.

URLs which host secrets must be available ever time a request is executed by DON nodes. For optimal security, it is recommended to expire the URLs when the off-chain secrets are no longer in use.

Automation Integration

Chainlink Functions can be used with Chainlink Automation in order to automatically trigger a Functions request.

1. Create & fund a new Functions billing subscription by running:
   npx hardhat functions-sub-create --network network_name_here --amount LINK_funding_amount_here
   Note: Ensure your wallet has a sufficient LINK balance before running this command.
   
   
2. Deploy the AutomationFunctionsConsumer client contract by running:
   npx hardhat functions-deploy-auto-client --network network_name_here --subid subscription_id_number_here --interval time_between_requests_here --verify true
   Note: Make sure ETHERSCAN_API_KEY or POLYGONSCAN_API_KEY environment variables are set. API keys for these services are freely available to anyone who creates an EtherScan or PolygonScan account.
   
   
3. Register the contract for upkeep via the Chainlink Automation web app here: https://automation.chain.link/
   • Be sure to set the Gas limit for the performUpkeep function to a high enough value. The recommended value is 1,000,000.
   • Find further documentation for working with Chainlink Automation here: https://docs.chain.link/chainlink-automation/introduction

Once the contract is registered for upkeep, check the latest response or error with the commands npx hardhat functions-read --network network_name_here --contract contract_address_here.

For debugging, use the command npx hardhat functions-check-upkeep --network network_name_here --contract contract_address_here to see if Automation needs to call performUpkeep. To manually trigger a request, use the command npx hardhat functions-perform-upkeep --network network_name_here --contract contract_address_here.

.
├── .github
│   ├── actions
│   │   └── setup
│   │       ├── action.yml
│   ├── workflows
│   │   ├── main.yml
│   │   ├── sync-upstream.yml
├── .husky
│   └── pre-commit
├── frontend
│   └── pre-commit
├── FunctionsSandboxLibrary
│   ├── Functions.js
│   ├── Logic.js
│   ├── Sandbox.js
│   ├── Validators.js
│   ├── buildRequest.js
│   ├── encryptSecrets.js
│   ├── getRequestConfig.js
│   ├── handler.js
│   ├── index.js
│   ├── simulateRequest.js
├── assets
├── contracts
│   ├── dev
│   │   ├── functions
│   │   │   ├── interfaces
│   │   │   └── or2
│   │   └── vendor
│   ├── AuthorizedReceiver.sol
│   ├── LinkToken.sol
│   ├── MockV3Aggregator.sol
│   ├── AutomatedFunctionsConsumer.sol
│   ├── FunctionsConsumer.sol
│   ├── ParametricInsurance.sol
│   ├── contract-design.md
├── scripts
│   ├── generateKeypair.js
│   ├── simulateFunctionsJavaScript.js
├── tasks
│   ├── Functions-billing
│   ├── Functions-client
│   │   ├── utils
│   │   │   ├── accounts.js
│   │   │   ├── balance.js
│   │   │   ├── block-numbers.js
│   │   │   ├── index.js
├── test/unit
│   ├── FunctionsConsumer.spec.js
├── .env.example
├── .gitignore
├── .solhint.json
├── .solhintignore
├── API-request-example.js
├── Functions-request-config.js
├── LICENSE
├── parametric-insurance-example.js
├── README.md
├── calculation-example.js
├── contract-diff.sh
├── contract.json
├── hardhat.config.js
├── network-config.js
├── package.json
├── parametric-insurance-contracts.md
├── passes.key
├── sepolia-guide.md
├── yarn.lock