Kubernetes部署只读文件系统错误 [英] Kubernetes deployment read-only filesystem error

问题描述

我在Kubernetes上部署Airflow时遇到错误(正是此版本的Airflow

I am facing an error while deploying Airflow on Kubernetes (precisely this version of Airflow https://github.com/puckel/docker-airflow/blob/1.8.1/Dockerfile) regarding writing permissions onto the filesystem.

豆荚的日志上显示的错误是:

The error displayed on the logs of the pod is:

sed: couldn't open temporary file /usr/local/airflow/sed18bPUH: Read-only file system
sed: -e expression #1, char 131: unterminated `s' command
sed: -e expression #1, char 118: unterminated `s' command
Initialize database...
sed: couldn't open temporary file /usr/local/airflow/sedouxZBL: Read-only file system
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/airflow/configuration.py", line 769, in
    ....
    with open(TEST_CONFIG_FILE, 'w') as f:
IOError: [Errno 30] Read-only file system: '/usr/local/airflow/unittests.cfg'

似乎文件系统是只读的，但我不明白为什么.我不确定这是否是 Kubernetes配置错误(我是否需要针对Pod的特殊RBAC?不知道)还是 Dockerfile 问题.

It seems that the filesystem is read-only but I do not understand why it is. I am not sure if it is a Kubernetes misconfiguration (do I need a special RBAC for pods ? No idea) or if it is a problem with the Dockerfile.

部署文件如下所示:

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: airflow
  namespace: test
spec:
  replicas: 1
  revisionHistoryLimit: 3
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 0
      maxSurge: 1
  template:
    metadata:
      labels:
        app: airflow
    spec:
      restartPolicy: Always
      containers:
      - name: webserver
        image: davideberdin/docker-airflow:0.0.4
        imagePullPolicy: Always
        resources:
          limits:
            cpu: 1
            memory: 1Gi
          requests:
            cpu: 50m
            memory: 128Mi
        securityContext:  #does not have any effect
          runAsUser: 0    #does not have any effect
        ports:
        - name: airflow-web
          containerPort: 8080
        args: ["webserver"]
        volumeMounts:
          - name: airflow-config-volume
            mountPath: /usr/local/airflow
            readOnly: false #does not have any effect
          - name: airflow-logs
            mountPath: /usr/local/logs
            readOnly: false #does not have any effect
      volumes:
      - name: airflow-config-volume
        secret:
          secretName: airflow-config-secret
      - name: airflow-parameters-volume
        secret:
          secretName: airflow-parameters-secret
      - name: airflow-logs
        emptyDir: {}

有什么想法可以使文件系统可写吗?容器以 USER airflow 的身份运行，但我认为该用户具有root特权.

Any idea how I can make the filesystem writable? The container is running as USER airflow but I think that this user has root privileges.

推荐答案

    volumeMounts:
      - name: airflow-config-volume
        mountPath: /usr/local/airflow
  volumes:
  - name: airflow-config-volume
    secret:
      secretName: airflow-config-secret

是您问题的根源，有两个原因:首先，您已破坏了气流用户的

Is the source of your problems, for two reasons: first, you have smashed the airflow user's home directory by volume mounting your secret onto the image directly into a place where the image expects a directory owned by airflow.

另外，尽管我必须启动一个集群以确认100％，但我很确定Secret卷已装入-并且我认为他们的ConfigMap朋友-已被读取-仅对Pod文件系统的投影；这种怀疑肯定符合您的经验.毫无疑问，对这些卷的更改不会传播回到kubernetes集群中，所以为什么假装否则.

Separately, while I would have to fire up a cluster to confirm 100%, I am pretty sure that Secret volume mounts -- and I think their ConfigMap friends -- are read-only projections into the Pod filesystems; that suspicion certainly appears to match your experience. There is certainly no expectation that changes to those volumes propagate back up into the kubernetes cluster, so why pretend otherwise.

如果您想继续尝试这种事情，实际上会对

If you want to continue to attempt such a thing, you do actually have influence over the defaultMode of the files projected into that volumeMount, so you could set them to 0666, but caveat emptor for sure. The short version is, by far, not to smash $AIRFLOW_HOME with a volume mount.

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