How to set the current host for Passport strategy callbackURL?

Question

How to set the current host for Passport strategy callbackURL?

I'm using the Passport-Linkedin strategy for Passport with Express, to allow users to log in with their LinkedIn profile.

I have the following code:

passport.use(new LinkedInStrategy({
    consumerKey: config.linkedin.LINKEDIN_API_KEY,
    consumerSecret: config.linkedin.LINKEDIN_SECRET_KEY,
    callbackURL: "http://localhost:3000/auth/linkedin/callback"
  },
  function(token, tokenSecret, profile, done) {
    // asynchronous verification, for effect...
    process.nextTick(function () {

      // To keep the example simple, the user's LinkedIn profile is returned to
      // represent the logged-in user.  In a typical application, you would want
      // to associate the LinkedIn account with a user record in your database,
      // and return that user instead.
      return done(null, profile);
    });
  }
));

On line 4, I have to set the full callback URL manually. I had one string for production and one for development, but my URLs keep changing, and so do the ports (I use 2 machines to develop).

How can I set the first portion of the URL (http://localhost:3000) automatically? Is there a property of express or app that would allow me to do that? Do I need to resort to an app.use(function(req, res){});?

Thanks!

javascript
node.js
express
passport.js

Answer 1

Old question, possibly y answer only valid for newer versions. However if someone runs into this, like me, solution is just to not specify a hostname in the callbackURL:

passport.use(new LinkedInStrategy({
    consumerKey: config.linkedin.LINKEDIN_API_KEY,
    consumerSecret: config.linkedin.LINKEDIN_SECRET_KEY,
    callbackURL: "/auth/linkedin/callback"
  },

To get this to work for heroku https redirect, we have to tell the system to trust the x-forwarded-protocol headers, by trusting the proxy:

passport.use(new LinkedInStrategy({
    consumerKey: config.linkedin.LINKEDIN_API_KEY,
    consumerSecret: config.linkedin.LINKEDIN_SECRET_KEY,
    callbackURL: "/auth/linkedin/callback",
    proxy: true
  },

Answer 2

In my config.js I have a cfg.site_url, that's one way, or you could look at req.host

http://expressjs.com/api.html#req.host

// Host: "example.com:3000"
req.hostname
// => "example.com"

Not sure if you have a req object in your context there.

Answer 3

Eventually solved this by dynamically building the callback URL from pieces of URL and the actual port. Not happy with this solution as it looks non-elegant, but could not find a way to get the actual URL without adding a middleware use call (which I'm sure impacts performance more than a simple string concatenation).