Custom API to let me upload avatars to my blob storage account.

sasApi.js

var azure = require('azure'); 
var qs = require('querystring');

function getSAS(accountName, accountKey, path, resourceType, sharedAccessPolicy) {                         
     return qs.encode(new azure.SharedAccessSignature(accountName, accountKey)
        .generateSignedQueryString(path, {}, resourceType, sharedAccessPolicy));                           
}

function formatDate(date){ 
        var raw = date.toJSON();
        //blob service does not like milliseconds on the end of the time so strip
        return raw.substr(0, raw.lastIndexOf('.')) + 'Z'; 
}

function createAvatarSas(name) {  
        var accountName = '<your blob account name>';
        var accountKey = '<your key>';         
        var host =   accountName + '.blob.core.windows.net';
        var canonicalizedResource = '/avatars/' + name;
        
        // Container exists now define a policy that provides write access                      
        // that starts immediately and expires in 5 mins        
        var sharedAccessPolicy = {
          AccessPolicy:{
                Permissions: azure.Constants.BlobConstants.SharedAccessPermissions.WRITE,
                //Start: //use for start time in future, beware of server time skew 
                Expiry: formatDate(new Date(new Date().getTime() + 1 * 60 * 1000)) //1 minutes from now
            }
        };
        
        //Generate the SAS for your BLOB
        var sasQueryString = getSAS(accountName,
                          accountKey, 
                          canonicalizedResource,
                          azure.Constants.BlobConstants.ResourceTypes.BLOB,
                          sharedAccessPolicy);
        
        //full path for resource with sas
        return 'https://' + host + canonicalizedResource + '?' + sasQueryString;                                         
}

exports.post = function(request, response) {
    // storage key
    var sas = createAvatarSas(request.user.userId.replace(':','') + '.png');
    response.send( { url: sas});
};