在Google Colab中使用redis-om JsonModel无法连接Redis Cloud的问题

问题 #

在Google Colab中使用redis-om的JsonModel将数据以JSON格式持久化到Redis Cloud时，出现连接错误。错误提示尝试连接localhost:6379，但实际Redis Cloud端口并非6379。

错误栈 #

OSError                                   Traceback (most recent call last)
/usr/local/lib/python3.10/dist-packages/redis/connection.py in connect(self)
    706         try:
---> 707             sock = self.retry.call_with_retry(
    708                 lambda: self._connect(), lambda error: self.disconnect(error)

10 frames
/usr/local/lib/python3.10/dist-packages/redis/retry.py in call_with_retry(self, do, fail)
     45             try:
---> 46                 return do()
     47             except self._supported_errors as error:

/usr/local/lib/python3.10/dist-packages/redis/connection.py in <lambda>()
    707             sock = self.retry.call_with_retry(
---> 708                 lambda: self._connect(), lambda error: self.disconnect(error)
    709             )

/usr/local/lib/python3.10/dist-packages/redis/connection.py in _connect(self)
   1005         if err is not None:
---> 1006             raise err
   1007         raise OSError("socket.getaddrinfo returned an empty list")

/usr/local/lib/python3.10/dist-packages/redis/connection.py in _connect(self)
    993                 # connect
---> 994                 sock.connect(socket_address)
    995 

OSError: [Errno 99] Cannot assign requested address

During handling of the above exception, another exception occurred:

ConnectionError                           Traceback (most recent call last)
<ipython-input-27-4ee06a3d036c> in <cell line: 24>()
     22 
     23 # Create an instance of the model class with some data
---> 24 person = Person(name="Alice", age=25, email="alice@example.com")
     25 
     26 # Save the instance to Redis as a JSON document

/usr/local/lib/python3.10/dist-packages/redis_om/model/model.py in __init__(self, *args, **kwargs)
   1676 
   1677     def __init__(self, *args, **kwargs):
---> 1678         if not has_redis_json(self.db()):
   1679             log.error(
   1680                 "Your Redis instance does not have the RedisJson module "

/usr/local/lib/python3.10/dist-packages/redis_om/checks.py in has_redis_json(conn)
     15     if conn is None:
     16         conn = get_redis_connection()
---> 17     command_exists = check_for_command(conn, "json.set")
     18     return command_exists
     19 

/usr/local/lib/python3.10/dist-packages/redis_om/checks.py in check_for_command(conn, cmd)
      7 @lru_cache(maxsize=None)
      8 def check_for_command(conn, cmd):
----> 9     cmd_info = conn.execute_command("command", "info", cmd)
     10     return None not in cmd_info
     11 

/usr/local/lib/python3.10/dist-packages/redis/client.py in execute_command(self, *args, **options)
   1264         pool = self.connection_pool
   1265         command_name = args[0]
---> 1266         conn = self.connection or pool.get_connection(command_name, **options)
   1267 
   1268         try:

/usr/local/lib/python3.10/dist-packages/redis/connection.py in get_connection(self, command_name, *keys, **options)
   1459         try:
   1460             # ensure this connection is connected to Redis
---> 1461             connection.connect()
   1462             # connections that the pool provides should be ready to send
   1463             # a command. if not, the connection was either returned to the

/usr/local/lib/python3.10/dist-packages/redis/connection.py in connect(self)
    711             raise TimeoutError("Timeout connecting to server")
    712         except OSError as e:
---> 713             raise ConnectionError(self._error_message(e))
    714 
    715         self._sock = sock

ConnectionError: Error 99 connecting to localhost:6379. Cannot assign requested address.

备注 #

• Redis Cloud端口不是6379，不清楚脚本为何尝试连接localhost
• Redis Cloud已配置Redis Stack模块
• 使用相同凭证可正常读写流数据，凭证无误
• Redis文档显示JsonModel可用于Redis Cloud

使用的脚本 #

!pip install redis
!pip install redis-om
import redis
import redis_om
from redis_om import JsonModel, Field


server_ip = "my correct redis cloud server_ip"
port =  "my correct redis cloud port"
password =  "my correct redis cloud password"

# Connect to the Redis instance
client = redis.Redis(host=server_ip, port=port, password=password)

# Define a custom model class using JsonModel
class Person(JsonModel):
    name: str = Field(index=True)
    age: int 
    email: str 

# Create an instance of the model class with some data
person = Person(name="Alice", age=25, email="alice@example.com")

# Save the instance to Redis as a JSON document
person.save()

# Print the ID and the JSON representation of the instance
print(person.id)
print(person.to_json())

解决方案 #

问题核心是JsonModel没有使用你手动创建的Redis连接，而是默认尝试连接本地Redis。以下两种方法可解决：

方法1：设置全局Redis连接 #

在定义模型前，调用redis_om.set_redis_connection()将你的远程连接设为全局默认：

# ... 原有连接代码 ...
client = redis.Redis(host=server_ip, port=port, password=password)

# 设置全局连接
redis_om.set_redis_connection(client)

# 再定义模型
class Person(JsonModel):
    name: str = Field(index=True)
    age: int 
    email: str 

方法2：在模型中指定连接 #

通过模型的Meta类直接绑定你的Redis连接：

# ... 原有连接代码 ...
client = redis.Redis(host=server_ip, port=port, password=password)

class Person(JsonModel):
    name: str = Field(index=True)
    age: int 
    email: str 

    class Meta:
        database = client

修改后的完整验证脚本 #

!pip install redis
!pip install redis-om
import redis
import redis_om
from redis_om import JsonModel, Field


server_ip = "my correct redis cloud server_ip"
port =  "my correct redis cloud port"
password =  "my correct redis cloud password"

# Connect to the Redis instance
client = redis.Redis(host=server_ip, port=port, password=password)

# 设置全局连接（或用Meta类方式）
redis_om.set_redis_connection(client)

# Define a custom model class using JsonModel
class Person(JsonModel):
    name: str = Field(index=True)
    age: int 
    email: str 

# Create an instance of the model class with some data
person = Person(name="Alice", age=25, email="alice@example.com")

# Save the instance to Redis as a JSON document
person.save()

# Print the ID and the JSON representation of the instance
print(person.id)
print(person.to_json())

原理说明 #

JsonModel默认通过get_redis_connection()获取连接，该方法未配置全局连接时会自动尝试连接localhost:6379。通过上述两种方式绑定你配置的Redis Cloud连接，即可解决错误。

内容的提问来源于stack exchange，提问作者a2z Tests