k8s_convert_ingress_to_v1.py

"""
Quick and dirty yaml conversion to move from old style k8s Ingresses to 
newer 1.22 style. 

Requires pyyaml installed.

Absolutely no guarantees are given on this being useful. Usage:

> python k8s_convert_ingress_to_v1.py some-ingresses.yaml

Once you are happy, just direct the output to a new file
> python k8s_convert_ingress_to_v1.py some-ingresses.yaml > new-ingresses.yaml

"""
import sys
try:
    import yaml
except ImportError:
    print("pyyaml is required. Please install with:")
    print("> pip install pyyaml")
    sys.exit(1)

if __name__ == "__main__":
    try:
        docs = yaml.load_all(open(sys.argv[1], "rt"), Loader=yaml.Loader)
    except IndexError:
        print("Usage: ./convert <YAML_FILE>")
        sys.exit(1)
    
    yaml_snippets = []
    for doc in docs:
        if not doc:
            continue
        if doc["kind"] != "Ingress":
            continue
        if "backend" in doc["spec"]:
            doc["spec"]["defaultBackend"] = doc["spec"]["backend"]
            del(doc["spec"]["backend"])

        if "rules" not in doc["spec"]:
            print(
                f'✗ {doc["metadata"]["name"]} has no rules, skipping',
                file=sys.stderr
            )
            continue  # might happen with kustomize patched stub ingresses

        for rule in doc["spec"]["rules"]:
            for path in rule["http"]["paths"]:
                backend = path["backend"]
                if "service" in backend:
                    print(
                        f'✗ {doc["metadata"]["name"]} > {rule["host"]} has path already updated, skipping',
                        file=sys.stderr
                    )
                    continue  # consider this already upgraded
                backend["service"] = dict(name=backend["serviceName"])
                path["pathType"] = "ImplementationSpecific"
                port = backend["servicePort"]
                if type(port) == int:
                    backend["service"]["port"] = dict(number=port)
                else:
                    backend["service"]["port"] = dict(name=port)
                del(backend["serviceName"])
                del(backend["servicePort"])

        doc["apiVersion"] = "networking.k8s.io/v1"
        yaml_snippets.append(yaml.dump(doc))
        print(
            f'✓ {doc["metadata"]["name"]} processed',
            file=sys.stderr
        )

    print("\n---\n\n".join(yaml_snippets))