camera-operator/camera-operator.py

#!/usr/bin/env python3
import asyncio
import logging
import os
import yaml
from base64 import b64decode
from kubernetes_asyncio.client.api_client import ApiClient
from kubernetes_asyncio import client, config, watch
from time import time
from urllib.parse import urlparse
import useful.logs

useful.logs.setup(json_fields={"msg": "message", "level": "levelname", "traceback": "exc_text"})
logger = logging.getLogger()

NAMESPACE = os.environ["MY_POD_NAMESPACE"]

LABEL_MANAGED_BY = "camera-operator"
with open("camera-service.yml") as stream:
    SERVICE_BODY = stream.read()
with open("camera-deployment.yml") as stream:
    DEPLOYMENT_BODY = stream.read()


def object_managed(i, now):
    """
    Check if Kubernetes object is managed according to CRD-s
    """
    if not i.metadata.labels:
        return False
    if i.metadata.labels.get("app.kubernetes.io/managed-by") != LABEL_MANAGED_BY:
        return False
    if i.metadata.labels.get("modified") == now:
        return False
    return True


async def cleanup_dangling_objects(v1, apps_api, now):
    await asyncio.sleep(2)
    logger.info("Cleaning up dangling deployments and services")
    resp = await v1.list_namespaced_service(NAMESPACE)
    for i in resp.items:
        if not object_managed(i, now):
            continue
        logger.debug("Removing service: %s/%s", NAMESPACE, i.metadata.name)
        await v1.delete_namespaced_service(i.metadata.name, NAMESPACE)
    resp = await apps_api.list_namespaced_deployment(NAMESPACE)
    for i in resp.items:
        if not object_managed(i, now):
            continue
        logger.debug("Removing deployment: %s/%s", NAMESPACE, i.metadata.name)
        await apps_api.delete_namespaced_deployment(i.metadata.name, NAMESPACE)


async def apply_changes(item, v1, now, apps_api):
    target = item["spec"]["target"]
    replicas = item["spec"].get("replicas")

    # Pull in secrets for the target URL
    secret_ref = item["spec"].get("secretRef")
    if secret_ref:
        secret = await v1.read_namespaced_secret(secret_ref, NAMESPACE)
        username = b64decode(secret.data.get("username", b"")).decode("ascii")
        password = b64decode(secret.data.get("password", b"")).decode("ascii")
        o = urlparse(target)
        netloc = o.netloc
        if "@" in netloc:
            _, netloc = o.netloc.split("@", 1)
        target = o._replace(netloc="%s:%s@%s" % (username, password, netloc)).geturl()

    name = "camera-%s" % item["metadata"]["name"]
    logger.info("Applying changes for %s", name)

    # Generate Deployment
    body = yaml.safe_load(DEPLOYMENT_BODY.replace("foobar", name))
    body["metadata"]["labels"]["app.kubernetes.io/managed-by"] = LABEL_MANAGED_BY
    body["metadata"]["labels"]["modified"] = now
    body["spec"]["template"]["spec"]["containers"][0]["args"] = [target]

    if replicas:
        body["spec"]["replicas"] = replicas
    try:
        await apps_api.replace_namespaced_deployment(name, NAMESPACE, body)
        logger.debug("Updated deployment %s/%s", NAMESPACE, name)
    except client.exceptions.ApiException:
        await apps_api.create_namespaced_deployment(NAMESPACE, body)
        logger.debug("Created deployment %s/%s", NAMESPACE, name)

    # Generate Service
    body = yaml.safe_load(SERVICE_BODY.replace("foobar", name))
    body["metadata"]["labels"]["app.kubernetes.io/managed-by"] = LABEL_MANAGED_BY
    body["metadata"]["labels"]["modified"] = now
    try:
        await v1.replace_namespaced_service(name, NAMESPACE, body)
        logger.debug("Updated service %s/%s", NAMESPACE, name)
    except client.exceptions.ApiException:
        await v1.create_namespaced_service(NAMESPACE, body)
        logger.debug("Created service %s/%s", NAMESPACE, name)


async def update_loop(v1, apps_api, api_instance):
    cleanup_task = None
    latest_version = None
    now = str(time())
    w = watch.Watch()
    args = "k-space.ee", "v1alpha1", NAMESPACE, "cams"
    logger.info("Subscribing to updates")
    async for event in w.stream(api_instance.list_namespaced_custom_object, *args, resource_version=latest_version):
        latest_version = event["object"]["metadata"]["resourceVersion"]
        if event["type"] == "ADDED":
            await apply_changes(event["object"], v1, now, apps_api)
        elif event["type"] == "DELETED":
            name = "camera-%s" % event["object"]["metadata"]["name"]
            logger.info("Remove %s" % name)
            try:
                await v1.delete_namespaced_service(name, NAMESPACE)
            except client.exceptions.ApiException:
                pass
            else:
                logger.debug("Remove service: %s/%s", NAMESPACE, name)
            try:
                await apps_api.delete_namespaced_deployment(name, NAMESPACE)
            except client.exceptions.ApiException:
                pass
            else:
                logger.debug("Remove deployment: %s/%s", NAMESPACE, name)
        if cleanup_task:
            cleanup_task.cancel()
        cleanup_task = asyncio.create_task(cleanup_dangling_objects(v1, apps_api, now))


async def main():
    if os.getenv("KUBECONFIG"):
        await config.load_kube_config()
    else:
        config.load_incluster_config()
    async with ApiClient() as api:
        v1 = client.CoreV1Api(api)
        apps_api = client.AppsV1Api()
        api_instance = client.CustomObjectsApi(api)
        while True:
            try:
                await update_loop(v1, apps_api, api_instance)
            except asyncio.exceptions.TimeoutError:
                pass


if __name__ == "__main__":
    loop = asyncio.new_event_loop()
    loop.run_until_complete(main())
    loop.close()