This is most evidently a metaphor. The thing to keep in mind when analyzing literature/poetry is that if you see figurative language making comparisons/drawing parallels between two differing things--instances where the meaning is not literal such as how injustice is not really a fire and has no flames--it's a safe bet you'll have on your hands a metaphor.
The host should be told if something is broken
A thank you note is appreciated after the diner
Flowers were sent to the martins from Alice
A formal dress is required
The first toast was offered by the host