embark/lib/modules/code_generator/code_templates/define-web3-simple.js.ejs

__mainContext.web3 = undefined;
web3 = new Web3(new Web3.providers.HttpProvider("<%- url -%>"));
web3.eth.getAccounts(function(err, accounts) {
  if (err) {
    return done(new Error(err));
  }
  web3.defaultAccount = accounts[0];
  <%- done  %>
});