If using a Eurail pass, how does one get from athens into mykonos?

Are there ferries covered by the pass. Or is this itenerary in greece just not possible unless out of pocket?

As far as I know, no ferries within Greece are covered by a Eurail pass. To Mikonos, there are ferries from Pireas (reached by metro from Athens) or Rafina (bus from Athens).
There really is no point getting a Eurail pass for a trip to Greece. The rail system there is very limited, services are mostly slower than buses, and train fares are very cheap.

Thanks. I will have a Eurail pass because I will be traveling all over europe. I plan on taking the free ferry from bari or brindisi. Any idea how much the ferry would be to mykonos

Between Italy and Greece, the Eurail pass, I believe, includes travel with Blue Star and Superfast Ferries which run from Ancona and Bari, but not from Brindisi.
Blue Star also run from Pireas to Mikonos and their web site (www.bluestarferries.com) shows a one-way fare of 24.20 euros.

Thank you so much. I really appreciate it.