This is a string that has no internal whitespace, comma, colon, curly-braces or square-braces. As such, it does not require double-quotes. For example, all the field names and the first two values in the following map are symbols.

a: one-is-a-lonely-number
b: "two-s-company"
c: 3's a crowd

Note that the field value for b is a symbol even though it is written with double-quotes. The double-quotes are unnecessary, but not invalid. The other way to think about it is: If you need to use double-quotes, you are not writing a symbol.

This is a number optionally followed by a scaling suffix.

Note: The suffix is case-sensitive; m and M differ.

This is a top-level field for Service, Pod and ReplicationController files and additionally found as a member of the ReplicationController’s template map. Common sub-fields (all optional unless otherwise indicated) are:

Strictly speaking, metadata is optional. However, we recommend including it along with the others, anyway, because name and labels facilitate later manipulation of the Service, Pod or ReplicationController.

This is often one of the fields in the metadata map. Valid label keys have two segements:

[prefix/]name

The prefix and “/” (slash, U+2F) portions are optional. The name portion is required and must be 1-63 characters in length. It must begin and end with with an alphanumeric character (i.e., [0-9A-Za-z]). The internal characters of name may include hyphen, dot and underscore. Here are some label keys, valid and invalid:

In the following example, labels and name comprise the map value of field metadata and the map value of labels has only one key/value pair.

metadata:
  labels:
    name: rabbitmq
  name: rabbitmq-controller

Note that in this example metadata.labels.name and metadata.name differ.

This is often one of the fields in the spec map of a Service or ReplicationController, but is also found at top-level. The map specifies field names and values that must match in order for the configured object to receive traffic. For example, the following fragment matches the labels example above.

spec:
  selector:
    name: rabbitmq

The field value is the TCP/UDP port where the service, pod or replication controller can be contacted for administration and control purposes. Similar fields are containerPort, hostPort and targetPort. Often, port is found in the same map with name and protocol. For example, here is a fragment that shows a list of two such maps as the value for field ports:

ports:
- name: dns
  port: 53
  protocol: UDP
- name: dns-tcp
  port: 53
  protocol: TCP

In this example, the port in both maps is identical, while the name and protocol differ.

The field value is a sub-map associating resource types with resource-quantity values. For limits the quantities describe maximum allowable values. A similar field is request, which describes desired values.

Valid resource types are cpu and memory. The units for cpu are Kubernetes Compute Unit seconds/second (i.e., CPU cores normalized to a canonical "Kubernetes CPU"). The units for memory are bytes.

In the following fragment, cpu is limited to 0.1 KCU and memory to 2GiB.

resources:
  limits:
    cpu: 100m
    memory: 2Gi

As shown here, the limits field is often found as part of the map value for the resources field.