Are Church Covenants and Vows Biblical?

Many churches now quire signing a so called church covenant. In some cases the documents seem to be limited to simple affirmations of commonly held christian beliefs, along with a commitment to support and serve the local body. Others seem to add commitments to very particular theological or moral imperatives. Some seem to suggest that participation in communion or being baptized are conditions upon signing these documents. I think i understand the practical reason for church covenants and vows, for discipline and efficiency. But are these biblical? I suppose this varies from place to place. Different churches will have, you know, different forms of this, tom, and you might want comment on what, you know,. typically it looks like