kubernetes pods 的 DNS 和气流工作者日志

Question

➜ k get pods -n edna    
NAME                              READY   STATUS    RESTARTS   AGE
airflow-79d5f59644-dd4k7          1/1     Running   0          16h
airflow-worker-67bcf7844b-rq7r8   1/1     Running   0          22h
backend-65bcb6546-wvvqj           1/1     Running   0          2d16h

so airflow 运行 in airflow-79d5f59644-dd4k7 pod 正在尝试从 airflow worker（celery/python 中提取日志，它运行一个简单的基于烧瓶的网络服务器处理日志）并且它不能因为域名 airflow-worker-67bcf7844b-rq7r8 在 airflow-79d5f59644-dd4k7 中未解析

*** Log file does not exist: /usr/local/airflow/logs/hello_world/hello_task/2020-07-14T22:05:12.123747+00:00/1.log
*** Fetching from: http://airflow-worker-67bcf7844b-rq7r8:8793/log/hello_world/hello_task/2020-07-14T22:05:12.123747+00:00/1.log
*** Failed to fetch log file from worker. HTTPConnectionPool(host='airflow-worker-67bcf7844b-rq7r8', port=8793): Max retries exceeded with url: /log/hello_world/hello_task/2020-07-14T22:05:12.123747+00:00/1.log (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7fd37d6a9790>: Failed to establish a new connection: [Errno -2] Name or service not known'))

我怎样才能完成这项工作？

我知道 Airflow 可以远程登录到 s3，但是有没有办法通过 POD 随机 hasotnames 路由请求？

我创建了一个 NodeType 服务，但 airflow 不知道该服务的 DNS 名称，并试图通过 airflow worker 的主机名访问日志（由 Celery 报告）。

➜ k get pods -n edna
NAME                              READY   STATUS    RESTARTS   AGE
airflow-79d5f59644-dd4k7          1/1     Running   0          16h
airflow-worker-67bcf7844b-rq7r8   1/1     Running   0          22h
backend-65bcb6546-wvvqj           1/1     Running   0          2d17h

kubectl get pods -n edna -l app=edna-airflow-worker \                                                                        
    -o go-template='{{range .items}}{{.status.podIP}}{{"\n"}}{{end}}'
'Tipz:' kgp -n edna -l app=edna-airflow-worker \ -o go-template='{{range .items}}{{.status.podIP}}{{" "}}{{end}}'
10.0.101.120

进入 airflow-79d5f59644-dd4k7 pod

k exec -ti -n edna airflow-79d5f59644-dd4k7 bash  

  [DEV] airflow-79d5f59644-dd4k7 app # curl -L http://airflow-worker-67bcf7844b-rq7r8:8793/log/hello_world/hello_task/2020-07-14T21:59:01.400678+00:00/1.log

curl: (6) Could not resolve host: airflow-worker-67bcf7844b-rq7r8; Unknown error
  [DEV] airflow-79d5f59644-dd4k7 app # curl -L http://10.0.101.120:8793/log/hello_world/hello_task/2020-07-14T21:59:01.400678+00:00/1.log
[2020-07-14 21:59:07,257] {{taskinstance.py:669}} INFO - Dependencies all met for <TaskInstance: hello_world.hello_task 2020-07-14T21:59:01.400678+00:00 [queued]>
[2020-07-14 21:59:07,341] {{taskinstance.py:669}} INFO - Dependencies all met for <TaskInstance: hello_world.hello_task 2020-07-14T21:59:01.400678+00:00 [queued]>
[2020-07-14 21:59:07,342] {{taskinstance.py:879}} INFO - 
--------------------------------------------------------------------------------
[2020-07-14 21:59:07,342] {{taskinstance.py:880}} INFO - Starting attempt 1 of 1
[2020-07-14 21:59:07,342] {{taskinstance.py:881}} INFO - 
--------------------------------------------------------------------------------
[2020-07-14 21:59:07,348] {{taskinstance.py:900}} INFO - Executing <Task(PythonOperator): hello_task> on 2020-07-14T21:59:01.400678+00:00
[2020-07-14 21:59:07,351] {{standard_task_runner.py:53}} INFO - Started process 5795 to run task
[2020-07-14 21:59:07,912] {{logging_mixin.py:112}} INFO - Running %s on host %s <TaskInstance: hello_world.hello_task 2020-07-14T21:59:01.400678+00:00 [running]> airflow-worker-67bcf7844b-rq7r8
[2020-07-14 21:59:07,989] {{logging_mixin.py:112}} INFO - Hello world! This is really cool!
[2020-07-14 21:59:07,989] {{python_operator.py:114}} INFO - Done. Returned value was: Hello world! This is really cool!
[2020-07-14 21:59:08,161] {{taskinstance.py:1065}} INFO - Marking task as SUCCESS.dag_id=hello_world, task_id=hello_task, execution_date=20200714T215901, start_date=20200714T215907, end_date=20200714T215908
[2020-07-14 21:59:17,070] {{logging_mixin.py:112}} INFO - [2020-07-14 21:59:17,070] {{local_task_job.py:103}} INFO - Task exited with return code 0
  [DEV] airflow-79d5f59644-dd4k7 app #

Answer 1

If a pod A wants to communicate to pod B, pod B has to be exposed with a service svc-b.

Then pod A can communicate with the svc-b.

这是规则。

对于你的情况，pod B 是 airflow-worker-67bcf7844b-rq7r8 :

kubectl -n edna expose airflow-worker-67bcf7844b-rq7r8 \
  --name airflow-worker \
  --port 8793 \
  --target-port 8793

现在可以随意使用 curl -L http://airflow-worker:8793/ 而不是 curl -L http://airflow-worker-67bcf7844b-rq7r8:8793/

Answer 2

解决方案

为 worker pod 的 deployment.yaml 提供以下 ENV AIRFLOW__CORE__HOSTNAME_CALLABLE：

env:
  - name: AIRFLOW__CORE__HOSTNAME_CALLABLE
    value: 'airflow.utils.net:get_host_ip_address'

或者只是改变airflow.cfg

然后 airflow 正在尝试通过 POD 的 IP 访问，如果你的 POD 公开端口 8793

，一切正常

kubernetes pods 的 DNS 和气流工作者日志

DNS for kubernetes pods and airflow worker logs

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