Consider the following schema snippet:

     templates:
        type: object
        additionalProperties: false
        patternProperties:
          "^[a-zA-Z][-a-zA-Z0-9]{0,29}$":
            $ref: "#/definitions/docker-component"

If there is a key in the templates JSON object that doesn't match that regex the error message looks like this (I'm formatting this with error.path + error.message):

/templates: Additional properties are not allowed ("postgresql-v9'6" was unexpected)

This is not very informative to the reader. Here's my proposal for a better error message:

/templates: "postgresql-v9'6" does not match any of these regexs: ^[a-zA-Z][-a-zA-Z0-9]{0,29}$.