There are always examples of figurative language in poems. Some are harder to find than others and some require a lot deeper analysis. Figurative language includes metaphors, similes, assonance, personification, alliteration etc. Once you learn the examples of figurative language, you will be able to idenfity it more easily.
From the poem, the following are examples of figurative language.
The harbor lights glaze over restless docks
This is personification. This is attributing human qualities, actions or characteristics to objects. The lights see: they are looking over the docks that are restless, meaning that the water is probably hitting against the docks continuously.
police cars cockroach through the tunnel streets:
This is metaphor and personification. The cars creep, like people, through the streets and only come out at night. This compares to how cockroaches are, and they scurry to the dark when the lights come on.
violence like a bug-infested rag is tossed
and fear is immanent as sound in the wind-swung bell
This has similes. It is comparison using like and as that compares violence to a bug infested rag and fear to the presence of the sound of bells swung by the wind.
the long day’s anger pants from sand and rocks;
but for this breathing night at last
This is personifciation. The day feels and has anger from sands and rocks, and the night is breathing as with lungs.