23 year old tight head prop Archer and 21 year old wing Barnes have both come through the Munster Academy and Development systems while Varley returned to Munster at the start of last season after a spell with London Wasps.
Commenting on the news Tony McGahan said. "It is extremely satisfying to see players come up through the Munster system whether is it from the Schools program for Stephen or the Youth program for Danny.
"For these two players to continue through the Academy system and now graduate to the Senior programme having accumulated Magners League time before reaching a professional contract gives a clear indication of the hard work done by the Academy programme.
"Damien's signing of a new contract reflects his hard work and single minded approach he has displayed since his return to Munster.
"His form for us has been rewarded with an International cap and we feel his continued progress will play a significant role in both Munster's and Irelands Rugby programmes.
Since returning to his native province, the Garryowen clubman has won 44 caps, and this term has played in 21 of Munster's 24 games to date.
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