Labels are a way to apply metadata to Docker object

Key

• alphanumeric string may have . or -
• lowercase
• . separates the namespace

Value

• any type can be represented as a string

Management

• labels on images, containers, local daemons, volumes, and networks are static for the lifetime of the object.
• docker swarm nodes and service can update label dynamically.

image and container

• Dockerfile - LABEL instruction

  • LABEL = =
• runtime

 docker run -l empty-label --label com.example.foo=bar ubuntu bash
 docker run --label-file ./labels ubuntu bash

• filter label

  docker images --filter "key=value"
  docker ps --filter "key=value"