truffle-plugin-verify

This truffle plugin allows you to automatically verify your smart contracts' source code on Etherscan, straight from the Truffle CLI.

I wrote a tutorial on my website that goes through the entire process of installing and using this plugin: Automatically verify Truffle smart contracts on Etherscan.

Note: This version of the plugin uses multi-file verification. If you want to use source code flattening instead for any reason, please use the legacy version (v0.4.x) of the plugin.

Installation / preparation

1. Install the plugin with npm or yarn

   npm install -D truffle-plugin-verify
   yarn add -D truffle-plugin-verify

2. Add the plugin to your truffle-config.js file

   module.exports = {
     /* ... rest of truffle-config */
   
     plugins: [
       'truffle-plugin-verify'
     ]
   }

3. Generate an API Key on your Etherscan account (see the Etherscan website)
4. Add your Etherscan API key to your truffle config (make sure to use something like dotenv so you don't commit the api key)

   module.exports = {
     /* ... rest of truffle-config */
   
     api_keys: {
       etherscan: 'MY_API_KEY'
     }
   }

Usage

Before running verification, make sure that you have successfully deployed your contracts to a public network with Truffle. The contract deployment must have completely finished without errors, including the final step of "saving migration to chain," so that the artifact files are updated with the required information. If this final step fails, try lowering your global gas limit in your truffle-config.js file, as saving migrations to chain uses your global gas limit and gas price, which could be problematic if you do not have sufficient ETH in your wallet to cover this maximum hypothetical cost.

After deployment, run the following command with one or more contracts that you wish to verify:

truffle run verify SomeContractName AnotherContractName --network networkName [--debug]

The network parameter should correspond to a network defined in the Truffle config file, with the correct network id set. The Ethereum mainnet and all main public testnets are supported.

For example, if we defined rinkeby as network in Truffle, and we wish to verify the SimpleStorage contract:

truffle run verify SimpleStorage --network rinkeby

This can take some time, and will eventually either return Pass - Verified or Fail - Unable to verify for each contract. Since the information we get from the Etherscan API is quite limited, it is currently impossible to retrieve any more information on verification failure. There should be no reason though why the verification should fail if the usage is followed correctly.

If you do receive a Fail - Unable to verify and you are sure that you followed the instructions correctly, please open an issue and I will look into it. Optionally, a --debug flag can also be passed into the CLI to output additional debug messages. It is helpful if you run this once before opening an issue and provide the output in your bug report.

Address override (Optional)

You can optionally provide an explicit address of the contract(s) that you wish to verify. This may be useful when you have deployed multiple instances of the same contract. The address is appended with @<address> as follows:

truffle run verify SimpleStorage@0x61C9157A9EfCaf6022243fA65Ef4666ECc9FD3D7 --network rinkeby

Constructor arguments override (Optional)

You can additionally provide an explicit constructor arguments for the contract using the --forceConstructorArgs option. This is useful if the contract was created by another contract rather an EOA, because truffle-plugin-verify cannot automatically retrieve constructor arguments in these cases. Note that the value needs to be prefixed with string: (e.g. --forceConstructorArgs string:0000).

truffle run verify MetaCoin --forceConstructorArgs string:0000000000000000000000000cb966d6a7702a4eff64009502653e302b3ec365 --network goerli

Debugging

You can pass an optional --debug flag into the plugin to display debug messages during the verification process. This is generally not necessary, but can be used to provide additional information when the plugin appears to malfunction.

truffle run verify SimpleStorage --network rinkeby

Usage with other chains

These instructions were written for verification on Etherscan for Ethereum mainnet and testnets, but it also works for verification on Snowtrace, PolygonScan, Optimistic Etherscan, Arbiscan, BscScan, HecoInfo and FtmScan. To verify your contracts on these chains make sure that your truffle-config.js file contains a network config for Avalanche, Polygon, Optimistic Ethereum, Artbitrum, BSC, HECO or FTM using the correct network_id (10 for Optimistic Ethereum, 56 for BSC mainnet, 97 for BSC testnet, 128 for HECO mainnet, 137 for Polygon, 250 for FTM, 256 for HECO testnet, 4002 for FTM testnet, 42161 for Arbitrum, 43113 for Avalanche testnet, 43114 for Avalanche mainnet, 80001 for Polygon testnet, 421611 for Arbitrum testnet).

Also make sure that you request an API key from Snowtrace, PolygonScan, BscScan, HecoInfo or FtmScan and add this key to your truffle-config.js file - Optimistic Etherscan and Arbiscan do not require additional API keys. If you want to verify your contracts on multiple chains, please provide separate API keys. If you take those steps, all other usage is exactly the same.

module.exports = {
  /* ... rest of truffle-config */

  api_keys: {
    etherscan: 'MY_API_KEY',
    bscscan: 'MY_API_KEY',
    hecoinfo: 'MY_API_KEY',
    ftmscan: 'MY_API_KEY',
    polygonscan: 'MY_API_KEY',
    snowtrace: 'MY_API_KEY',
  }
}

Notes

This plugin has a naming conflict with the truffle-security plugin, so when using both truffle-security and truffle-plugin-verify in the same project, truffle run etherscan can be used instead of truffle run verify for truffle-plugin-verify.

Donations

If you've used this plugin and found it helpful in your workflow, please consider sending some Ξ or tokens to 0xe126b3E5d052f1F575828f61fEBA4f4f2603652a or kalis.eth.