Can you programmatically access current Heroku dyno id/name?

Question

On Heroku, can you programmatically, from within an app, get some kind of identifier for the dyno currently executing your code? For example the dyno name (e.g. "web.1" or "worker.1"), or some other id.

If yes, how to do this in Java?

Answer 1

There is always the hostname of the machine (which looks something like d.LONG_GUID. I suppose (though haven't tried) that this should work:

String localhostname = java.net.InetAddress.getLocalHost().getHostName();

Also, a little known secret, but you can get the "web.1", "web.2" id's by looking at the value of the environment variable PS1

String hostId = System.getenv("PS1")

EDIT 2013-July-26

As per Heroku changelog, the local environment variable DYNO now replaces PS, which replaced PS1.

Answer 2

Heroku team have addressed that issue and now the Dyno Manager adds DYNO environment variables that holds identifier of your Dyno e.g. web.1, web.2, foo.1 etc. However, the variable is still experimental and subject to change or removal.

You can get value of that variable using System.getenv(String) in Java.

Example:

final String dynoId = System.getenv("DYNO");
final Matcher matcher = Pattern.compile("(\\w+)\\.(\\d+)").matcher(dynoId);

String id = null;

if(matcher.find()) {
    id = matcher.group(2); // returns index: 1
    // matcher.group(1) - returns name: web
}

I hope that will help