1. Why We Need to Define the Application Runtime There are more runtime choices. Traditional application runtimes include physical machines, virtual machines, and cloud hosts. In the container era, the common runtimes are Docker and Kubernetes. These runtimes no longer present us with a single runtime choice. Application topologies are more complex.

1. Labels 1.1 What Labels Are Labels are key-value pairs attached to an object. You can add labels directly when the object is created, or modify them dynamically afterwards. Label format: 1 2 3 4 "labels": { "key1" : "value1", "key2" : "value2" } Format requirements: Key: must be unique Value: must start with a letter or a digit, may contain letters, digits, hyphens, dots, and underscores, and is at most 63 characters long 1.