Authenticating with the Walmart.io API in Node.js

main.js

make_wm_request: async function({method,url,http_body,vendor_id,consumer_id,consumer_pk,channel_type} = {}){
  return new Promise(async function(resolve,reject){

		//if you don't have a PEM-formatted private key (we didn't), generate one real quick
		var pk_chunked = chunkSubstr(consumer_pk, 64).join("\n")
		pk_chunked = "-----BEGIN PRIVATE KEY-----\n" + pk_chunked + "\n-----END PRIVATE KEY-----\n"


    var epoch_timestamp = Date.now()

		//generate the payload to be signed
    var input = consumer_id + "\n" + url + "\n" + method + "\n" + epoch_timestamp + "\n"


		//you'll need to require crypto somewhere along the way
    const sign = crypto.createSign('SHA256');
    sign.write(input);
    sign.end();
    const sig = sign.sign(pk_chunked, 'base64');


    var headers = {
      "Accept":"application/json",
      "WM_SVC.NAME":"Warehouse Supplier Services",
      "WM_QOS.CORRELATION_ID":"0000001",
      "WM_SEC.TIMESTAMP":epoch_timestamp,
      "WM_SEC.AUTH_SIGNATURE":sig,
      "WM_CONSUMER.ID":consumer_id,
      "WM_CONSUMER.CHANNEL.TYPE":channel_type,
      "Content-Type":"application/json"
    }
    var options = {
      method: method,
      url: url,
      headers: headers
			body: http_body
    }


		//use your favorite request package here (axios, request, etc)
    request(options,function(e,r,body){

			if (e)
				resolve({error:e,message:"Request failed"})

			else
				resolve({success:true,result:body})

    })



		//breaks up a string into chunks of a certain size. Returns array of strings
		function chunkSubstr(str, size) {
			const numChunks = Math.ceil(str.length / size)
			const chunks = new Array(numChunks)

			for (let i = 0, o = 0; i < numChunks; ++i, o += size) {
				chunks[i] = str.substr(o, size)
			}

			return chunks
		}
  })
}