python - 无法访问 Python 的 init.py 文件中的 Kubernetes env var

Question

我在访问 python 应用程序的 init.py 文件中的 Kubernetes 环境变量时遇到问题。然而，它似乎在其他文件中可用。

我的 init.py 文件包含此代码 app.config.from_object(os.environ['APP_SETTINGS'])。 APP_SETTINGS 的值取决于我的环境，值为 config.DevelopmentConfig、config.StagingConfig 或 config.ProductionConfig 。从这里，我的应用程序从我的 config.py 文件中提取配置，如下所示:

import os
basedir = os.path.abspath(os.path.dirname(__file__))

class Config(object):
  WTF_CSRF_ENABLED = True
  SECRET_KEY = 'you-will-never-guess'
  APP_SETTINGS = os.environ['APP_SETTINGS'] # For debug purposes


class DevelopmentConfig(Config):
  TEMPLATES_AUTO_RELOAD = True
  DEBUG = True

class StagingConfig(Config):
  DEBUG = True

class ProductionConfig(Config):
  DEBUG = False

当我在 docker-compose 的开发环境中本地设置 APP_SETTINGS 时，就像这样......

environment:
  - APP_SETTINGS=config.DevelopmentConfig

一切都很好。当我在 Secrets 文件中设置 APP_SETTINGS=config.StagingConfig 并将其部署到 Kubernetes 中的 Staging pod 时，出现以下错误:

Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/werkzeug/utils.py", line 434, in import_string
    return getattr(module, obj_name)
AttributeError: module 'config' has no attribute 'StagingConfig
'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/werkzeug/utils.py", line 436, in import_string
    raise ImportError(e)
ImportError: module 'config' has no attribute 'StagingConfig
'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "manage.py", line 3, in <module>
    from app import app
  File "/root/app/__init__.py", line 11, in <module>
    app.config.from_object(os.environ['APP_SETTINGS'])
  File "/usr/local/lib/python3.6/site-packages/flask/config.py", line 168, in from_object
    obj = import_string(obj)
  File "/usr/local/lib/python3.6/site-packages/werkzeug/utils.py", line 443, in import_string
    sys.exc_info()[2])
  File "/usr/local/lib/python3.6/site-packages/werkzeug/_compat.py", line 137, in reraise
    raise value.with_traceback(tb)
  File "/usr/local/lib/python3.6/site-packages/werkzeug/utils.py", line 436, in import_string
    raise ImportError(e)
werkzeug.utils.ImportStringError: import_string() failed for 'config.StagingConfig\n'. Possible reasons are:
- missing __init__.py in a package;
- package or module path not included in sys.path;
- duplicated package or module name taking precedence in sys.path;
- missing module, class, function or variable;
Debugged import:
- 'config' found in '/root/config.py'.
- 'config.StagingConfig\n' not found.
Original exception:
ImportError: module 'config' has no attribute 'StagingConfig
'
upgrading database schema...
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/werkzeug/utils.py", line 434, in import_string
    return getattr(module, obj_name)
AttributeError: module 'config' has no attribute 'StagingConfig
'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/werkzeug/utils.py", line 436, in import_string
    raise ImportError(e)
ImportError: module 'config' has no attribute 'StagingConfig
'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "manage.py", line 3, in <module>
    from app import app
  File "/root/app/__init__.py", line 11, in <module>
    app.config.from_object(os.environ['APP_SETTINGS'])
  File "/usr/local/lib/python3.6/site-packages/flask/config.py", line 168, in from_object
    obj = import_string(obj)
  File "/usr/local/lib/python3.6/site-packages/werkzeug/utils.py", line 443, in import_string
    sys.exc_info()[2])
  File "/usr/local/lib/python3.6/site-packages/werkzeug/_compat.py", line 137, in reraise
    raise value.with_traceback(tb)
  File "/usr/local/lib/python3.6/site-packages/werkzeug/utils.py", line 436, in import_string
    raise ImportError(e)
werkzeug.utils.ImportStringError: import_string() failed for 'config.StagingConfig\n'. Possible reasons are:
- missing __init__.py in a package;
- package or module path not included in sys.path;
- duplicated package or module name taking precedence in sys.path;
- missing module, class, function or variable;
Debugged import:
- 'config' found in '/root/config.py'.
- 'config.StagingConfig\n' not found.
Original exception:
ImportError: module 'config' has no attribute 'StagingConfig
'
starting metriculous web server...
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/werkzeug/utils.py", line 434, in import_string
    return getattr(module, obj_name)
AttributeError: module 'config' has no attribute 'StagingConfig
'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/werkzeug/utils.py", line 436, in import_string
    raise ImportError(e)
ImportError: module 'config' has no attribute 'StagingConfig
'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "manage.py", line 3, in <module>
    from app import app
  File "/root/app/__init__.py", line 11, in <module>
    app.config.from_object(os.environ['APP_SETTINGS'])
  File "/usr/local/lib/python3.6/site-packages/flask/config.py", line 168, in from_object
    obj = import_string(obj)
  File "/usr/local/lib/python3.6/site-packages/werkzeug/utils.py", line 443, in import_string
    sys.exc_info()[2])
  File "/usr/local/lib/python3.6/site-packages/werkzeug/_compat.py", line 137, in reraise
    raise value.with_traceback(tb)
  File "/usr/local/lib/python3.6/site-packages/werkzeug/utils.py", line 436, in import_string
    raise ImportError(e)
werkzeug.utils.ImportStringError: import_string() failed for 'config.StagingConfig\n'. Possible reasons are:
- missing __init__.py in a package;
- package or module path not included in sys.path;
- duplicated package or module name taking precedence in sys.path;
- missing module, class, function or variable;
Debugged import:
- 'config' found in '/root/config.py'.
- 'config.StagingConfig\n' not found.
Original exception:
ImportError: module 'config' has no attribute 'StagingConfig

但是，当我像这样 app.config.from_object('config.StagingConfig') 在 init.py 文件中硬编码 APP_SETTINGS 值并部署到 Kubernetes 时，它工作正常。当我这样做时，我什至可以通过登录我的 pod 并运行 echo $APP_SETTINGS 来确认 Kubernetes 设置中声明的 APP_SETTINGS env var 是否存在。

对我做错了什么有什么想法吗？

编辑#1 - 添加我的deployment.yaml 文件

kind: Deployment
apiVersion: apps/v1beta2
metadata:
  annotations:
    deployment.kubernetes.io/revision: '4'
  selfLink: /apis/apps/v1beta2/namespaces/tools/deployments/met-staging-myapp
  resourceVersion: '51731234'
  name: met-staging-myapp
  uid: g1fce905-1234-56y4-9c15-12de61100d0a
  creationTimestamp: '2018-01-29T17:22:14Z'
  generation: 6
  namespace: tools
  labels:
    app: myapp
    chart: myapp-1.0.1
    heritage: Tiller
    release: met-staging
spec:
  replicas: 1
  selector:
    matchLabels:
      app: myapp
      release: met-staging
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: myapp
        release: met-staging
    spec:
      containers:
        - name: myapp-web
          image: 'gitlab.ourdomain.com:4567/ourspace/myapp:web-latest'
          ports:
            - containerPort: 80
              protocol: TCP
          env:
            - name: APP_SETTINGS
              valueFrom:
                secretKeyRef:
                  name: myapp-creds
                  key: APP_SETTINGS
            - name: AWS_ACCESS_KEY_ID
              valueFrom:
                secretKeyRef:
                  name: myapp-creds
                  key: AWS_ACCESS_KEY_ID
            - name: AWS_SECRET_ACCESS_KEY
              valueFrom:
                secretKeyRef:
                  name: myapp-creds
                  key: AWS_SECRET_ACCESS_KEY
          resources: {}
          terminationMessagePath: /dev/termination-log
          terminationMessagePolicy: File
          imagePullPolicy: Always
        - name: myapp-celery
          image: 'gitlab.ourdomain.com:4567/ourspace/myapp:celery-latest'
          env:
            - name: APP_SETTINGS
              valueFrom:
                secretKeyRef:
                  name: myapp-creds
                  key: APP_SETTINGS
            - name: AWS_ACCESS_KEY_ID
              valueFrom:
                secretKeyRef:
                  name: myapp-creds
                  key: AWS_ACCESS_KEY_ID
            - name: AWS_SECRET_ACCESS_KEY
              valueFrom:
                secretKeyRef:
                  name: myapp-creds
                  key: AWS_SECRET_ACCESS_KEY
          resources: {}
          terminationMessagePath: /dev/termination-log
          terminationMessagePolicy: File
          imagePullPolicy: Always
        - name: rabbit
          image: 'rabbitmq:alpine'
          env:
            - name: RABBITMQ_DEFAULT_USER
              value: rabbit_user
            - name: RABBITMQ_DEFAULT_PASS
              value: fake_pw
          resources: {}
          terminationMessagePath: /dev/termination-log
          terminationMessagePolicy: File
          imagePullPolicy: IfNotPresent
      restartPolicy: Always
      terminationGracePeriodSeconds: 30
      dnsPolicy: ClusterFirst
      securityContext: {}
      imagePullSecrets:
        - name: gitlab-registry
      schedulerName: default-scheduler
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 1
      maxSurge: 1
  revisionHistoryLimit: 10
  progressDeadlineSeconds: 600
status:
  observedGeneration: 6
  replicas: 1
  updatedReplicas: 1
  readyReplicas: 1
  availableReplicas: 1
  conditions:
    - type: Available
      status: 'True'
      lastUpdateTime: '2018-01-29T17:22:14Z'
      lastTransitionTime: '2018-01-29T17:22:14Z'
      reason: MinimumReplicasAvailable
      message: Deployment has minimum availability.
    - type: Progressing
      status: 'True'
      lastUpdateTime: '2018-05-25T10:20:49Z'
      lastTransitionTime: '2018-02-16T20:29:45Z'
      reason: NewReplicaSetAvailable
      message: >-
        ReplicaSet "met-staging-myapp-2615c4545f" has successfully
        progressed.

Answer 1

werkzeug.utils.ImportStringError: import_string() failed for 'config.StagingConfig\n'. Possible reasons are:

它非常清楚地向您显示模块名称尾部有一个换行符，对于尝试 echo something | base64 的人来说，这是一个非常非常常见的错误并将该值放入 kubernetes Secret 。正确的方法是通过 kubectl create secret generic myapp-creds --from-literal=APP_SETTINGS=config.StagingConfig ，或printf '%s' config.StagingConfig | base64 。或者，当然，停止将非 secret 文本放入 secret 中并使用 ConfigMap或者只是传统环境value: config.StagingConfig设置，并保留Secret构造 Secret值。