Azure Redis Cache is not working

Question

Hello,

I have an unusuall issue, I have multiple basic tier azure redis caches and the ones that are newly created (past 3 days) no matter from where, terraform or the portal, they all have connectivity issues, I cannot connect to any of them because of timeout. I have 3 old ones in the same tier and they work perfectly.

Does anyone experience similar things or is it just for me? Maybe any solution for it?

Answer 1

It sounds like you are experiencing connectivity issues with your newly created Azure Redis caches. Here are some potential causes and solutions to consider:

1. Firewall Rules: Ensure that your client IP address is added to the firewall rules for the new Azure Redis caches. You can check this in the Azure portal under the Firewall settings for your cache.
2. Private Endpoint Configuration: If you are using a private endpoint, verify that it is configured correctly. Make sure that Enable public network access is set appropriately, especially if you need to connect from outside the virtual network.
3. Public IP Address Change: If you have any networking resources that rely on the cache's public IP address, check if the public IP address has changed since the caches were created.
4. Network Configuration: Check your virtual network configuration to ensure that it allows connectivity to the new caches.
5. Server Maintenance: Sometimes, planned or unplanned maintenance can affect connectivity. You can check the Errors (Type: Failover) metric in the Azure portal to see if there are any ongoing issues.

If none of these solutions resolve the issue, consider testing connectivity using the Redis command line tool redis-cli or using PSPING in Azure PowerShell to diagnose further.

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References:

• Troubleshoot Azure Cache for Redis connectivity
• Connectivity configuration issues

Answer 2

Hi Énok Gábor,

Thank you for reaching out to Microsoft Q&A.

I understand you are experiencing timeout and connectivity issues with newly created Azure Redis Cache instances in the Basic tier, while your older instances function without any problems.

Please review the following suggestions and let us know if they resolve your issue. Firstly, check the firewall rules to ensure the new caches allow your client IP addresses. In the Azure portal, verify and add your client IP if it's missing. For those using private endpoints, confirm that public network access is enabled if you need to connect from outside the virtual network.

Next, examine the Network Security Groups (NSG) to see if any rules are blocking traffic to ports 6379 or 6380, which Redis uses. Also, ensure the cache hostname resolves correctly from your client machine by using the command nslookup .redis.cache.windows.net. Double-check your connection string and ports. Make sure your application uses the correct connection string, the right port (usually 6380 for SSL), and the appropriate password. Compare these settings with your old working caches and align the new ones accordingly.

If the initial solution does not resolve the connectivity issue with Azure Redis Cache,

Please share the below information further investigating the issue;

• Are the new Redis Cache instances configured with the same firewall rules as the old working instances?
• Can you confirm which IP addresses or ranges are allowed?
• Are you using private endpoints or virtual network integration with these new caches?
• If so, have you verified the private endpoint configuration and DNS resolution inside the VNet?
• Can you perform basic network connectivity tests (such as ping or redis-cli connect) to the Redis Cache hostname and port from your client machine?
• Is the connection string used by your application exactly the same for old and new caches, including hostnames, ports (6379 for non-SSL or 6380 for SSL), and authentication keys?
• Are there any Network Security Groups (NSGs) or firewall rules on the client subnet or Redis subnet that might be blocking traffic on ports 6379 or 6380?
• What is the Redis Cache tier and size of the newly created instances compared to the old ones?
• Are there any differences in tier or configuration?
• Have you enabled diagnostic logging on the new Redis Cache instances? What errors or warnings does the diagnostic log indicate?
• Are there any recent changes in your network environment, such as changes in DNS configuration, proxy settings, or VPNs, that might affect connectivity?
• Can you share the exact timeout or error messages you receive when trying to connect?

Your detailed response will help us identify and resolve the issue more effectively.

Microsoft Reference documents:

• Troubleshoot Azure Cache for Redis connectivity issues: https://learn.microsoft.com/en-us/azure/azure-cache-for-redis/cache-troubleshoot-connectivity
• Troubleshoot Azure Cache for Redis latency and timeouts: https://learn.microsoft.com/en-us/azure/azure-cache-for-redis/cache-troubleshoot-timeouts
• Configure firewall rules for Azure Cache for Redis:https://learn.microsoft.com/en-us/cli/azure/redis/firewall-rules
• Azure Cache for Redis network isolation and private endpoints: https://learn.microsoft.com/en-us/azure/azure-cache-for-redis/cache-network-isolation
• Use Network Security Groups with Azure Cache for Redis: https://www.trendmicro.com/cloudoneconformity/knowledge-base/azure/RedisCache/use-network-security-…
• Troubleshoot DNS name resolution issues with Azure Redis Cache: https://learn.microsoft.com/en-us/answers/questions/1298631/troubleshooting-temporary-dns-name-reso…
• .Azure Service Health - Check for regional outages and advisories: https://learn.microsoft.com/en-us/azure/service-health/service-health-overview
• Enable diagnostic logging for Azure Cache for Redis: https://learn.microsoft.com/en-us/azure/azure-cache-for-redis/monitor-diagnostics Hope this helps. Do let us know if you have any further queries.

Kindly let us know if the above helps or you need further assistance on this issue.