Encode Transaction and called MakerDAO DsProxyActions Contract

.sol

/* ------------------------ */
// Call Vault Manager (DsProxyActions.sol)
/* ------------------------ */
function callVaultManager (bytes memory _data) public payable {
  IDSProxy proxy = IDSProxy(dss_proxy);
  proxy.execute.value(msg.value)(vault_manager, _data);
}

function callVaultManager (uint256 _amount, bytes memory _data) public {
  IDSProxy proxy = IDSProxy(dss_proxy);
  proxy.execute.value(_amount)(vault_manager, _data);
}

// ETH Vault Functions
/* ------------------------ */
function openETHVault(
      uint wadD, 
      bytes32 ilk
  ) public payable {
      GenerateCallData proxy = GenerateCallData(data_generation);
      bytes memory data = proxy.openLockETHAndDraw(
          dai_manager,
          dai_jug,
          dai_ethJoin,
          dai_daiJoin,
          ilk,
          wadD
      );
      callVaultManager(data);
  }