What characters are allowed in kubernetes port and container names?

Question

What patterns are valid in kubernetes for the names of containers and ports?

I had underscores in the names of ports and containers and got an error. Replacing the underscores with hyphens worked.

Answer 1

Container names and port names must conform to the RFC 1123 definition of a DNS label.

Names must be no longer than 63 characters, must start and end with a lowercase letter or number, and may contain lowercase letters, numbers, and hyphens.

Expressed as a regular expression:

[a-z0-9]([-a-z0-9]*[a-z0-9])?

Here's the applicable code in GitHub for checking container names, checking port names, and defining acceptable names.