I have a tenant who rents a house from me in an HOA community. They had a bankruptcy a long time ago due to the real estate market. Their credit should be clean enough now to buy. Even if not, I'm considering selling the house to them via seller financing.

Concern here is: if they fail to pay the HOA dues, fines, etc. will the HOA foreclose on my house or merely put a lien on it? I don't want to seller finance the house to them if there is a risk that the HOA will take the house and thus the collateral out from under me if they become a problem. I imagine if they stop paying the mortgage they will have also stopped paying the HOA dues, etc. as well.

Ask the HOA if they would foreclose, you just need to make sure you foreclose first and pay off the HOA debt.