psycopg2: 无法将主机名转换为地址:名称或服务未知

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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:

127.0.0.1 - - [13/Jul/2023:17:35:05 -0500] "GET /read HTTP/1.1" 301 0 "-" "PostmanRuntime/7.32.3"
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

内部服务器错误:/read/

编辑:
添加负责的 views.py 部分:

from django.http import JsonResponse
from django.views.decorators.csrf import csrf_exempt
from django.db import connection
from django.conf import settings
import psycopg2
import logging

# 设置日志记录
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

@csrf_exempt
def read(request):
    try:
        conn = psycopg2.connect(
            host=settings.DATABASES['default']['HOST'],
            dbname=settings.DATABASES['default']['NAME'],
            user=settings.DATABASES['default']['USER'],
            password=settings.DATABASES['default']['PASSWORD']
        )
        with conn.cursor() as cur:
            cur.execute('SELECT * FROM visitor_count;')
            data = cur.fetchall()

        conn.close()

        for item in data:
            response = item[1]
            return JsonResponse({'statusCode': 200, 'data': response})

    except Exception as e:
        logger.error("处理 GET 请求时发生错误:%s", str(e))
        return JsonResponse({'statusCode': 500, 'message': '内部服务器错误'}, status=500)

从 settings.py 中:

# 数据库配置
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': os.environ.get('DATABASE'),
        'USER': os.environ.get('DB_USERNAME'),
        'PASSWORD': os.environ.get('DB_PASSWORD'),
        'HOST': os.environ.get('DB_HOST'),
        'PORT': os.environ.get('DB_PORT', '5432'),
    }
}

环境变量通过一个密钥传递给容器:

密钥:

apiVersion: v1
kind: Secret
metadata:
  name: backend-secret
  namespace: resume
data:
  host: cmVzdW1lLXBvc3RncmVzcWwtcHJpbWFyeS1obAo=
  database: 已编辑
  db_username: 已编辑
  db_password: 已编辑
  db_port: NTQzMgo=
  secret_key: 已编辑

部署:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: resume-backend
  labels:
    app: resume-backend
spec:
  template:
    metadata:
      name: resume-backend
      labels:
        app: resume-backend
    spec:
      containers:
      - name: resume-backend
        image: rustybridge/resume-backend:1.0
        imagePullPolicy: Always
        env:
        - name: DB_HOST
          valueFrom:
            secretKeyRef:
              name: backend-secret
              key: host
        - name: DATABASE
          valueFrom:
            secretKeyRef:
              name: backend-secret
              key: database
        - name: DB_USERNAME
          valueFrom:
            secretKeyRef:
              name: backend-secret
              key: db_username
        - name: DB_PASSWORD
          valueFrom:
            secretKeyRef:
              name: backend-secret
              key: db_password
        - name: DB_PORT
          valueFrom:
            secretKeyRef:
              name: backend-secret
              key: db_port
        - name: SECRET_KEY
          valueFrom:
            secretKeyRef:
              name: backend-secret
              key: secret_key
        ports:
        - containerPort: 8000
          name: listen
  selector:
    matchLabels:
      app: resume-backend
  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:

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

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:

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

Internal Server Error: /read/

EDIT:
Adding part of views.py responsible:

from django.http import JsonResponse
from django.views.decorators.csrf import csrf_exempt
from django.db import connection
from django.conf import settings
import psycopg2
import logging

# Set up logging
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

@csrf_exempt
def read(request):
    try:
        conn = psycopg2.connect(
            host=settings.DATABASES['default']['HOST'],
            dbname=settings.DATABASES['default']['NAME'],
            user=settings.DATABASES['default']['USER'],
            password=settings.DATABASES['default']['PASSWORD']
        )
        with conn.cursor() as cur:
            cur.execute('SELECT * FROM visitor_count;')
            data = cur.fetchall()

        conn.close()

        for item in data:
            response = item[1]
            return JsonResponse({'statusCode': 200, 'data': response})

    except Exception as e:
        logger.error("An error occurred while processing the GET request: %s", str(e))
        return JsonResponse({'statusCode': 500, 'message': 'Internal Server Error'}, status=500)

From settings.py:

# Database
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': os.environ.get('DATABASE'),
        'USER': os.environ.get('DB_USERNAME'),
        'PASSWORD': os.environ.get('DB_PASSWORD'),
        'HOST': os.environ.get('DB_HOST'),
        'PORT': os.environ.get('DB_PORT', '5432'),
    }
}

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

Secret:

apiVersion: v1
kind: Secret
metadata:
  name: backend-secret
  namespace: resume
data:
  host: cmVzdW1lLXBvc3RncmVzcWwtcHJpbWFyeS1obAo= 
  database: REDACTED
  db_username: REDACTED
  db_password: REDACTED
  db_port: NTQzMgo=
  secret_key: REDACTED

Deployment:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: resume-backend
  labels:
    app: resume-backend
spec:
  template:
    metadata:
      name: resume-backend
      labels:
        app: resume-backend
    spec:
      containers:
      - name: resume-backend
        image: rustybridge/resume-backend:1.0
        imagePullPolicy: Always
        env:
        - name: DB_HOST
          valueFrom:
            secretKeyRef:
              name: backend-secret
              key: host
        - name: DATABASE
          valueFrom:
            secretKeyRef:
              name: backend-secret
              key: database
        - name: DB_USERNAME
          valueFrom:
            secretKeyRef:
              name: backend-secret
              key: db_username
        - name: DB_PASSWORD
          valueFrom:
            secretKeyRef:
              name: backend-secret
              key: db_password
        - name: DB_PORT
          valueFrom:
            secretKeyRef:
              name: backend-secret
              key: db_port
        - name: SECRET_KEY
          valueFrom:
            secretKeyRef:
              name: backend-secret
              key: secret_key
        ports:
        - containerPort: 8000
          name: listen
  selector:
    matchLabels:
      app: resume-backend
  replicas: 2

root@resume-backend-677cd68846-9vrm6:/srv/app# env | grep DB_HOST
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
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