When someone files a bankruptcy, it is filed electronically and is public record. Anyone can find out you filed if they know where to look.
Someone in interested in doing the search can simply open a PACER account and discovered you filed.
All creditors and co-debtors on any debts you have will be noticed when the case is filed as you will have to include this information in your petition. You will also have to list anyone you owe child support or alimony to in the petition.
Some employers will discover the bankruptcy filing if they pull a credit report during the hiring process you or while you are employed.