using-a-fallback-director.vcl

# api - you have to run this locally
backend rails {
  .host = "localhost";
  .port = "3000";
}


# local version of ember app
backend ember_app {
  .host = "localhost";
  .port = "4200";
}

# pre-built version of the previous app, hosted on an s3 bucket or whatever
backend ember_app_prebuilt {
  .host = "ember_app.development.yourdomain.com";
  .port = "80";
}


# this is the "varnish routing magic"
sub vcl_recv {

  # Defaults to rails
  set req.backend = rails;
  set req.grace = 60s;
  set req.hash_always_miss = false;


  # builds a "fallback director" - if the first backend is unhealthy, it will use the second
  new ember_director = directors.fallback();
  ember_director.add_backend(ember_app);
  ember_director.add_backend(ember_app_prebuilt);


  # routes traffic based on the request
  if(req.url ~ "^/cool-url/") {
    # send to the embeer-cli app instead
    set req.backend = ember_director;

    # this tells s3 which domain you're asking for
    set req.http.Host = "ember_app.development.yourdomain.com";

    # serve index.html for noon-asset requests
    if (req.http.file_ext == "") {
      set req.url = "/index.html";
    }

    return(pass);
  }


}