How to add metadata to nodejs grpc call

Question

I\'d like to know how to add metadata to a nodejs grpc function call. I can use channel credentials when making the client with

var client = new proto.Docume         


        

Answer 1

I eventually worked it out through introspecting the grpc credentials code and modifying the implementation to expose an inner function. In the grpc module in the node_modules, file grpc/src/node/src/credentials.js add the line

exports.CallCredentials = CallCredentials;

after CallCredentials is imported. Then, in your code, you can write something like

var meta = grpc.Metadata();
meta.add('key', 'value');
var extra_creds = grpc.credentials.CallCredentials.createFromPlugin(
  function (url, callback) {
    callback(null, meta);
  }
)

Then use extra_creds in the client builder

var creds = grpc.credentials.combineChannelCredentials(
  grpc.credentials.createSsl(),
  extra_creds,
)

Now you can make your client

var client = new proto.Document(
  'some.address:8000',
  creds,
)