swagger-k8s-crd-codegen.py

#!/usr/bin/python3

import yaml
import os
import shutil

from prance import ResolvingParser
from jinja2 import Template


# This tool reads a swagger.yml to produce Kubernetes CRDs
# of the specified models. This parser looks for special
# attributes in your model definition. Please define the following:
#    * x-groupName = group name to use for generated CRD (e.g. ndslabs.org)
#    * x-version = version name to use for generated CRD (e.g. v1)
#    * x-singular = name for a single CRD of this type (e.g. workbenchuserapp)
#    * x-plural = name for multiple CRD of this type (e.g. workbenchuserapps)
#    * x-kind: CamelCase kind for this CRD (e.g. WorkbenchUserApp)
#    * x-scope: "Namespaced" or "Cluster" (share to all namespaces)
#    * x-shortNames: list of shorter string aliases for this CRD

# Describe the swagger spec to read
# TODO: Read from args and/or env
SWAGGER_URL = './swagger.yml'
DEFN_SUBPATH = 'definitions'

# Template inputs and outputs
TEMPLATE_URL = './template.crd.yaml'
OUTPUT_DIR = 'target'

# Extra customizations added to our swagger models
GROUPNAME_KEY = 'x-groupName'
VERSION_KEY = 'x-version'
PLURAL_KEY = 'x-plural'
SINGULAR_KEY = 'x-singular'
KIND_KEY = 'x-kind'
SCOPE_KEY = 'x-scope'
SHORTNAMES_KEY = 'x-shortNames'


CRD_GEN_COMMENT = """
## This file was generated by Workbench API server.
## Any manual changes to this file may be overwritten.
"""


def write_crd(defn, output_file):
    with open(TEMPLATE_URL, "r") as f:
        template = Template(f.read())

        # Grab custom vars from swagger spec
        crd_kind = defn[KIND_KEY]
        crd_version = defn[VERSION_KEY]
        crd_plural = defn[PLURAL_KEY]
        crd_singular = defn[SINGULAR_KEY]
        crd_groupname = defn[GROUPNAME_KEY]
        crd_scope = defn[SCOPE_KEY]
        crd_shortnames = defn[SHORTNAMES_KEY]

        # Strip out customizations
        crd_spec_schema = defn
        for key in [KIND_KEY, VERSION_KEY, PLURAL_KEY, SINGULAR_KEY, GROUPNAME_KEY, SCOPE_KEY, SHORTNAMES_KEY]:
            crd_spec_schema.pop(key)

        full_crd = template.render(
            crd_gen_comment=CRD_GEN_COMMENT,
            crd_kind=crd_kind,
            crd_version=crd_version,
            crd_plural=crd_plural,
            crd_singular=crd_singular,
            crd_groupname=crd_groupname,
            crd_scope=crd_scope,
            crd_shortnames=yaml.dump(crd_shortnames),
            crd_spec_schema=yaml.dump(crd_spec_schema)
        )

    # Write resulting CRD
    with open(output_file, "w") as f:
        print("Writing " + output_file)
        f.write(full_crd)
    return


if __name__ == '__main__':
    # Clean old models
    #if os.path.exists(OUTPUT_DIR):
    #    shutil.rmtree(OUTPUT_DIR)

    # Create output directory
    if not os.path.exists(OUTPUT_DIR):
        os.mkdir(OUTPUT_DIR)

    # Parse swagger spec, resolve any $refs
    parser = ResolvingParser(SWAGGER_URL)
    for defn in parser.specification[DEFN_SUBPATH]:
        schema = parser.specification[DEFN_SUBPATH][defn]
        if 'x-groupName' in schema:
            plural = schema[PLURAL_KEY]

            file_name = "%s.crd.yml" % plural
            write_crd(schema, os.path.join(OUTPUT_DIR, file_name))