help request: upstream with eureka discovery got no host allowed while connecting to upstream!

[lchpersonal]

Description

Access an upstream discovered through Eureka service via version 3.12 of apisix, where the Eureka registered address is a domain name: dev-test.com, not an IP address. Access via http:dev-test.com/HJService/info works alone. However, when accessed via apisix, the following error occurs:

2025/05/20 11:10:39 [error] 1470660#1470660: *359 [lua] balancer.lua:388: run(): failed to set server peer [dev-test.com:80] err: no host allowed while connecting to upstream, client: 10.10.120.117, server: _, request: "GET /HJService/info HTTP/1.1", host: "172.30.94.83:9080"

dns resolve worked good:

nslookup dev-test.com 10.255.255.88
Server:         10.255.255.88
Address:        10.255.255.88#53

Non-authoritative answer:
Name:   dev-test.com
Address: 172.30.9.198

I tried modifying eureka/init.lua, adding logic for domain name resolution to IP addresses. The process worked, but I found another issue: the forwarded request cannot carry the original domain name of the service discovery target node.

How to resolve this problem?

中文描述

通过apisix 3.12版本访问通过Eureka服务发现的上游节点，其中Eureka注册的地址为域名（dev-test.com，而非IP地址）。单独通过http://dev-test.com/HJService/info访问是正常的，但通过apisix访问时出现以下错误：

2025/05/20 11:10:39 [error] 1470660#1470660: *359 [lua] balancer.lua:388: run(): failed to set server peer [dev-test.com:80] err: no host allowed while connecting to upstream, client: 10.10.120.117, server: _, request: "GET /HJService/info HTTP/1.1", host: "172.30.94.83:9080"

DNS解析正常：

nslookup dev-test.com 10.255.255.88  
Server:         10.255.255.88  
Address:        10.255.255.88#53  

Non-authoritative answer:  
Name:   dev-test.com  
Address: 172.30.9.198  

我尝试修改eureka/init.lua，增加域名解析为IP的逻辑，流程可以走通，但发现另一个问题：转发的请求无法携带服务发现目标节点的原始域名。

如何解决这个问题？

Environment/环境

• APISIX version (run apisix version): 3.12
• Operating system (run uname -a): Linux 172.30.94.83 5.10.0-60.18.0.50.oe2203.x86_64 change: added doc of how to load plugin. #1 SMP Wed Mar 30 03:12:24 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
• OpenResty / Nginx version (run openresty -V or nginx -V): openresty/1.27.1.1
• etcd version, if relevant (run curl http://127.0.0.1:9090/v1/server_info): etcd_version":"3.4.0
• APISIX Dashboard version, if relevant:
• Plugin runner version, for issues related to plugin runners:
• LuaRocks version, for installation issues (run luarocks --version):

[Baoyuantop]

Can you provide the apisix config file? Also are there any other error logs?

[lchpersonal]

Can you provide the apisix config file? Also are there any other error logs?

After a day's effort, I have resolved this issue. The original eureka/init.lua had two problems:

1. It does not support domain names for registered nodes
2. After modifying the init.lua code to add the logic for resolving domain names to IPs, it could not use the original upstream domain name as the header host.

I will submit a PR when I have time to contribute my modifications.