Question

我有一个简单的脚本，可以监视Kubernetes事件，然后将消息发布到NATS服务器：

#!/usr/bin/env python
import asyncio
import argparse
import json
import logging
import os

from kubernetes import client, config, watch

from nats.aio.client import Client as NATS
from nats.aio.errors import ErrConnectionClosed, ErrTimeout, ErrNoServers

# monkey patch
from kube import local_load_oid_token
config.kube_config.KubeConfigLoader._load_oid_token = local_load_oid_token

parser = argparse.ArgumentParser()
parser.add_argument('--in-cluster', help="use in cluster kubernetes config", action="store_true")
parser.add_argument('-a', '--nats-address', help="address of nats cluster", default=os.environ.get('NATS_ADDRESS', None))
parser.add_argument('-d', '--debug', help="enable debug logging", action="store_true")
parser.add_argument('-p', '--publish-events', help="publish events to NATS", action="store_true")
parser.add_argument('--output-events', help="output all events to stdout", action="store_true", dest='enable_output')
parser.add_argument('--connect-timeout', help="NATS connect timeout (s)", type=int, default=10, dest='conn_timeout')
parser.add_argument('--max-reconnect-attempts', help="number of times to attempt reconnect", type=int, default=1, dest='conn_attempts')
parser.add_argument('--reconnect-time-wait', help="how long to wait between reconnect attempts", type=int, default=10, dest='conn_wait')
args = parser.parse_args()

logger = logging.getLogger('script')
ch = logging.StreamHandler()
if args.debug:
    logger.setLevel(logging.DEBUG)
    ch.setLevel(logging.DEBUG)
else:
    logger.setLevel(logging.INFO)
    ch.setLevel(logging.INFO)
formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
ch.setFormatter(formatter)
logger.addHandler(ch)

if not args.nats_address:
    logger.critical("No NATS cluster specified")
    exit(parser.print_usage())
else:
    logger.debug("Using nats address: %s", args.nats_address)

if args.in_cluster:
    config.load_incluster_config()
else:
    try:
        config.load_kube_config()
    except Exception as e:
        logger.critical("Error creating Kubernetes configuration: %s", e)
        exit(2)

v1 = client.CoreV1Api()


async def run(loop):
    nc = NATS()
    try:
        await nc.connect(args.nats_address, loop=loop, connect_timeout=args.conn_timeout, max_reconnect_attempts=args.conn_attempts, reconnect_time_wait=args.conn_wait)
        logger.info("Connected to NATS at %s..." % (nc.connected_url.netloc))
    except Exception as e:
        exit(e)

    #print("Connected to NATS at {}...".format(nc.connected_url.netloc))

    async def get_node_events():
        w = watch.Watch()
        for event in w.stream(v1.list_node):
            accepted = ["DELETED"]
            if event['type'] in accepted:
                logger.info("Event: %s %s %s" % (event['type'], event['object'].kind, event['object'].metadata.name))
                msg = {'type':event['type'],'object':event['raw_object']}
                logger.debug("Raw Message: %s"  % msg)
                await nc.publish("k8s_events", json.dumps(msg).encode('utf-8'))
                if args.enable_output:
                    print(json.dumps(msg))

    await get_node_events()
    await nc.flush(timeout=3)
    await nc.close()




if __name__ == '__main__':

    loop = asyncio.get_event_loop()
    loop.create_task(run(loop))
    try:
        loop.run_forever()
    except KeyboardInterrupt:
        logger.info('keyboard shutdown')
        tasks = asyncio.gather(*asyncio.Task.all_tasks(loop=loop), loop=loop, return_exceptions=True)
        tasks.add_done_callback(lambda t: loop.stop())
        tasks.cancel()

        # Keep the event loop running until it is either destroyed or all
        # tasks have really terminated
        while not tasks.done() and not loop.is_closed():
            loop.run_forever()
    finally:
        logger.info('closing event loop')
        loop.close()

在启用事件发布的情况下运行此命令时，我可以看到正在输出事件JSON。

但是，由于某种原因，我的接收者实际上并未收到有关删除事件的NATS消息。

如何调试将其发送到主题的消息？我可以添加任何可以验证通过代码将其传达到主题的消息吗？
我的异步逻辑在这里正确吗？
为什么删除事件不能按照这种逻辑进入主题？

Answer 1

您可以验证通过NATS服务器日志进行的邮件传递。在配置NATS服务器时，请使用传递给NATS服务器的 -DV 标志或通过以下命令在NATS配置文件中临时启用调试/跟踪：

debug=true
trace=true

您应该看到类似这样的内容：

[31070] 2019/09/10 13:34:40.426198 [DBG] 127.0.0.1:53203 - cid:6 - Client connection created
[31070] 2019/09/10 13:34:40.426582 [TRC] 127.0.0.1:53203 - cid:6 - <<- [CONNECT {"verbose":false,"pedantic":false,"tls_required":false,"name":"NATS Sample Subscriber","lang":"go","version":"1.7.0","protocol":1,"echo":true}]
[31070] 2019/09/10 13:34:40.426614 [TRC] 127.0.0.1:53203 - cid:6 - <<- [PING]
[31070] 2019/09/10 13:34:40.426625 [TRC] 127.0.0.1:53203 - cid:6 - ->> [PONG]
[31070] 2019/09/10 13:34:40.426804 [TRC] 127.0.0.1:53203 - cid:6 - <<- [SUB k8s_events  1]
[31070] 2019/09/10 13:34:40.426821 [TRC] 127.0.0.1:53203 - cid:6 - <<- [PING]
[31070] 2019/09/10 13:34:40.426827 [TRC] 127.0.0.1:53203 - cid:6 - ->> [PONG]
[31070] 2019/09/10 13:34:44.167844 [DBG] ::1:53206 - cid:7 - Client connection created
[31070] 2019/09/10 13:34:44.168352 [TRC] ::1:53206 - cid:7 - <<- [CONNECT {"verbose":false,"pedantic":false,"tls_required":false,"name":"NATS Sample Publisher","lang":"go","version":"1.7.2","protocol":1,"echo":true}]
[31070] 2019/09/10 13:34:44.168383 [TRC] ::1:53206 - cid:7 - <<- [PING]
[31070] 2019/09/10 13:34:44.168390 [TRC] ::1:53206 - cid:7 - ->> [PONG]
[31070] 2019/09/10 13:34:44.168594 [TRC] ::1:53206 - cid:7 - <<- [PUB k8s_events 11]
[31070] 2019/09/10 13:34:44.168607 [TRC] ::1:53206 - cid:7 - <<- MSG_PAYLOAD: ["{json data}"]
[31070] 2019/09/10 13:34:44.168623 [TRC] 127.0.0.1:53203 - cid:6 - ->> [MSG k8s_events 1 11]
[31070] 2019/09/10 13:34:44.168648 [TRC] ::1:53206 - cid:7 - <<- [PING]
[31070] 2019/09/10 13:34:44.168653 [TRC] ::1:53206 - cid:7 - ->> [PONG]

使用连接ID，您可以看到连接ID 7向k8s_events发布了11个字节（协议消息PUB k8s_events 11及其后的消息有效负载），并且接收到连接ID 6（订阅者）消息（MSG k8s_events 1 11）。

这是一种检查客户是否正在发布消息以及订阅者是否正在收听正确主题的方法。

从Kubernetes事件调试NATS消息

1 个答案: