Just for info.
When the engine is not running you will have a hard pedal, but this does not mean you have brakes. Without engine vacuum (comes into play when engine is running) you do not have any servo assistance.
I recently rolled my car slightly further on the sloping drive with the keys out, ie no engine running, i released the handbrake and tried to stop the bloody thing with the foot pedal but although the pedal was solid the car still rolled into the garage wall. What an idiot I am. Hard pedal without engine is normal and does not indicate anything.
Just my opinion but the pool of fluid is a dead giveaway. Could be hose, could be calliper seal giving way etc. whatever the cause, either hose or seal, I would check all my brakes as they should be exactly the same age on each axle. Therefore if one side is old enough to fail the other side may do so also in short order.