[springs]

Glass would be tricky to make from scratch, simply because of the temperatures required to produce it. Post apocalyptic, though, would scavenging of already produced glass be more likely?
In terms of the food, it does come down to how it's stored/prepared. Curing meat and fish extends that (next to an old smokery would be a good postapocalytic positioning, memo to self), canned stuff should keep well past its useby/bb (although Chrispy is right about citrus fruits, and preserves keep easily a year or two if they're not opened.)