Pandas Fill rows missing in date range

Question

I have a Dataframe that represents a hotel reservations by date:

date        volume  city
2020-01-05      10    NY
2020-01-06      10    NY
2020-01-07      30    NY

The Dataframe is ultimately being written to the Database and because of that I need to have a complete range of dates from a given point in the past to a given point in the future, for example, the Dataframe (for entire 2020) I need should look like this:

date        volume  city
2020-01-01       0    NY
2020-01-02       0    NY
2020-01-03       0    NY
2020-01-04       0    NY
2020-01-05      10    NY
2020-01-06      10    NY
2020-01-07      30    NY
...
2020-12-31       0    NY

It's important that all the rows filling the range have a volume=0 and the city is repeated in the entire dataset.

How can I effective convert my Dataframe to fill dates missing in the range ?