psycopg2: 无法将主机名转换为地址：名称或服务未知

huangapple
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英文:

psycopg2: Could not translate host name to address: Name or service not known

问题

我正尝试使用 psycopg2 和 Django 应用程序连接到 PostgreSQL 数据库。运行应用程序的 Pod 报告以下错误：

  1. 127.0.0.1 - - [13/Jul/2023:17:35:05 -0500] "GET /read HTTP/1.1" 301 0 "-" "PostmanRuntime/7.32.3"
  2. 在处理 GET 请求时发生错误：无法将主机名 "resume-postgresql-primary-hl" 转换为地址：名称或服务未知
  4. 内部服务器错误：/read/

编辑：
添加负责的 views.py 部分：

  1. from django.http import JsonResponse
  2. from django.views.decorators.csrf import csrf_exempt
  3. from django.db import connection
  4. from django.conf import settings
  5. import psycopg2
  6. import logging
  8. # 设置日志记录
  9. logging.basicConfig(level=logging.INFO)
  10. logger = logging.getLogger(__name__)
  12. @csrf_exempt
  13. def read(request):
  14.     try:
  15.         conn = psycopg2.connect(
  16.             host=settings.DATABASES['default']['HOST'],
  17.             dbname=settings.DATABASES['default']['NAME'],
  18.             user=settings.DATABASES['default']['USER'],
  19.             password=settings.DATABASES['default']['PASSWORD']
  20.         )
  21.         with conn.cursor() as cur:
  22.             cur.execute('SELECT * FROM visitor_count;')
  23.             data = cur.fetchall()
  25.         conn.close()
  27.         for item in data:
  28.             response = item[1]
  29.             return JsonResponse({'statusCode': 200, 'data': response})
  31.     except Exception as e:
  32.         logger.error("处理 GET 请求时发生错误：%s", str(e))
  33.         return JsonResponse({'statusCode': 500, 'message': '内部服务器错误'}, status=500)

从 settings.py 中：

  1. # 数据库配置
  2. DATABASES = {
  3.     'default': {
  4.         'ENGINE': 'django.db.backends.postgresql_psycopg2',
  5.         'NAME': os.environ.get('DATABASE'),
  6.         'USER': os.environ.get('DB_USERNAME'),
  7.         'PASSWORD': os.environ.get('DB_PASSWORD'),
  8.         'HOST': os.environ.get('DB_HOST'),
  9.         'PORT': os.environ.get('DB_PORT', '5432'),
  10.     }
  11. }

环境变量通过一个密钥传递给容器：

密钥：

  1. apiVersion: v1
  2. kind: Secret
  3. metadata:
  4.   name: backend-secret
  5.   namespace: resume
  6. data:
  7.   host: cmVzdW1lLXBvc3RncmVzcWwtcHJpbWFyeS1obAo=
  8.   database: 已编辑
  9.   db_username: 已编辑
  10.   db_password: 已编辑
  11.   db_port: NTQzMgo=
  12.   secret_key: 已编辑

部署：

  1. apiVersion: apps/v1
  2. kind: Deployment
  3. metadata:
  4.   name: resume-backend
  5.   labels:
  6.     app: resume-backend
  7. spec:
  8.   template:
  9.     metadata:
  10.       name: resume-backend
  11.       labels:
  12.         app: resume-backend
  13.     spec:
  14.       containers:
  15.       - name: resume-backend
  16.         image: rustybridge/resume-backend:1.0
  17.         imagePullPolicy: Always
  18.         env:
  19.         - name: DB_HOST
  20.           valueFrom:
  21.             secretKeyRef:
  22.               name: backend-secret
  23.               key: host
  24.         - name: DATABASE
  25.           valueFrom:
  26.             secretKeyRef:
  27.               name: backend-secret
  28.               key: database
  29.         - name: DB_USERNAME
  30.           valueFrom:
  31.             secretKeyRef:
  32.               name: backend-secret
  33.               key: db_username
  34.         - name: DB_PASSWORD
  35.           valueFrom:
  36.             secretKeyRef:
  37.               name: backend-secret
  38.               key: db_password
  39.         - name: DB_PORT
  40.           valueFrom:
  41.             secretKeyRef:
  42.               name: backend-secret
  43.               key: db_port
  44.         - name: SECRET_KEY
  45.           valueFrom:
  46.             secretKeyRef:
  47.               name: backend-secret
  48.               key: secret_key
  49.         ports:
  50.         - containerPort: 8000
  51.           name: listen
  52.   selector:
  53.     matchLabels:
  54.       app: resume-backend
  55.   replicas: 2

当我在本地主机上运行时，它可以正常工作（连接到数据库并返回数据）。

Pod 中的 nslookup 也正常工作：

  1. root@resume-backend-677cd68846-m22h8:/srv/app# nslookup resume-postgresql-primary-hl
  2. Server:     10.96.0.10
  3. Address:    10.96.0.10#53
  5. Name:   resume-postgresql-primary-hl.resume.svc.cluster.local
  6. Address: 10.244.0.114

我无法弄清楚发生了什么。有任何想法吗？

英文:

I am attempting to connect to a PostgreSQL DB using psycopg2 and a django app. The pods running the application report the following error:

  1. 127.0.0.1 - - [13/Jul/2023:17:35:05 -0500] "GET /read HTTP/1.1" 301 0 "-" "PostmanRuntime/7.32.3"  
  2. An error occurred while processing the GET request: could not translate host name "resume-postgresql-primary-hl
  3. " to address: Name or service not known
  5. Internal Server Error: /read/

EDIT:
Adding part of views.py responsible:

  1. from django.http import JsonResponse
  2. from django.views.decorators.csrf import csrf_exempt
  3. from django.db import connection
  4. from django.conf import settings
  5. import psycopg2
  6. import logging
  8. # Set up logging
  9. logging.basicConfig(level=logging.INFO)
  10. logger = logging.getLogger(__name__)
  12. @csrf_exempt
  13. def read(request):
  14.     try:
  15.         conn = psycopg2.connect(
  16.             host=settings.DATABASES['default']['HOST'],
  17.             dbname=settings.DATABASES['default']['NAME'],
  18.             user=settings.DATABASES['default']['USER'],
  19.             password=settings.DATABASES['default']['PASSWORD']
  20.         )
  21.         with conn.cursor() as cur:
  22.             cur.execute('SELECT * FROM visitor_count;')
  23.             data = cur.fetchall()
  25.         conn.close()
  27.         for item in data:
  28.             response = item[1]
  29.             return JsonResponse({'statusCode': 200, 'data': response})
  31.     except Exception as e:
  32.         logger.error("An error occurred while processing the GET request: %s", str(e))
  33.         return JsonResponse({'statusCode': 500, 'message': 'Internal Server Error'}, status=500)

From settings.py:

  1. # Database
  2. DATABASES = {
  3.     'default': {
  4.         'ENGINE': 'django.db.backends.postgresql_psycopg2',
  5.         'NAME': os.environ.get('DATABASE'),
  6.         'USER': os.environ.get('DB_USERNAME'),
  7.         'PASSWORD': os.environ.get('DB_PASSWORD'),
  8.         'HOST': os.environ.get('DB_HOST'),
  9.         'PORT': os.environ.get('DB_PORT', '5432'),
  10.     }
  11. }

The environmental variables are passed to the container with a secret:

Secret:

  1. apiVersion: v1
  2. kind: Secret
  3. metadata:
  4.   name: backend-secret
  5.   namespace: resume
  6. data:
  7.   host: cmVzdW1lLXBvc3RncmVzcWwtcHJpbWFyeS1obAo= 
  8.   database: REDACTED
  9.   db_username: REDACTED
  10.   db_password: REDACTED
  11.   db_port: NTQzMgo=
  12.   secret_key: REDACTED

Deployment:

  1. apiVersion: apps/v1
  2. kind: Deployment
  3. metadata:
  4.   name: resume-backend
  5.   labels:
  6.     app: resume-backend
  7. spec:
  8.   template:
  9.     metadata:
  10.       name: resume-backend
  11.       labels:
  12.         app: resume-backend
  13.     spec:
  14.       containers:
  15.       - name: resume-backend
  16.         image: rustybridge/resume-backend:1.0
  17.         imagePullPolicy: Always
  18.         env:
  19.         - name: DB_HOST
  20.           valueFrom:
  21.             secretKeyRef:
  22.               name: backend-secret
  23.               key: host
  24.         - name: DATABASE
  25.           valueFrom:
  26.             secretKeyRef:
  27.               name: backend-secret
  28.               key: database
  29.         - name: DB_USERNAME
  30.           valueFrom:
  31.             secretKeyRef:
  32.               name: backend-secret
  33.               key: db_username
  34.         - name: DB_PASSWORD
  35.           valueFrom:
  36.             secretKeyRef:
  37.               name: backend-secret
  38.               key: db_password
  39.         - name: DB_PORT
  40.           valueFrom:
  41.             secretKeyRef:
  42.               name: backend-secret
  43.               key: db_port
  44.         - name: SECRET_KEY
  45.           valueFrom:
  46.             secretKeyRef:
  47.               name: backend-secret
  48.               key: secret_key
  49.         ports:
  50.         - containerPort: 8000
  51.           name: listen
  52.   selector:
  53.     matchLabels:
  54.       app: resume-backend
  55.   replicas: 2
  1. root@resume-backend-677cd68846-9vrm6:/srv/app# env | grep DB_HOST
  2. DB_HOST=resume-postgresql-primary-hl

When I run it on localhost, it works (connects to the DB and returns the data)

Nslookup from the pods is also working:

> root@resume-backend-677cd68846-m22h8:/srv/app# nslookup resume-postgresql-primary-hl
Server: 10.96.0.10
Address: 10.96.0.10#53
>
>Name: resume-postgresql-primary-hl.resume.svc.cluster.local
Address: 10.244.0.114

I can't figure out what is going on. Any ideas?

答案1

得分: 0

问题出在秘密值的编码方式上（它们都包含了一个换行符）

解决方法是将它们编码为这样：
echo -n 'resume-postgresql-primary-hl' | base64 -w0

来源：https://github.com/kubernetes/kubernetes/issues/23404#issuecomment-203404986

英文:

The issue was with how the secret values were encoded (they all contained a newline)

What worked was to encode them like this:
echo -n 'resume-postgresql-primary-hl' | base64 -w0

credit: https://github.com/kubernetes/kubernetes/issues/23404#issuecomment-203404986

huangapple
  • 本文由 发表于 2023年7月14日 06:53:47
  • 转载请务必保留本文链接：https://go.coder-hub.com/76683734.html
  • django
  • kubernetes
  • psycopg2
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