fix(docker): nginx caches wrong upstream IP after restart when host DNS search domains resolve service names externally

TL;DR

Fix: Contributor kanson1996 diagnosed: nginx resolved upstream service names to IPs once at startup and cached them, so after a container restart the IP was stale whenever host DNS search domains resolved the service names externally. Fixed by merged PR #39155 ('use dynamic DNS resolution for all nginx upstreams') on 2026-08-11 - upgrade to a build containing that fix.

The error

Issue langgenius/dify#39154 (closed, 60 comments): ### Self Checks - [x] I have read the [Contributing Guide](https://github.com/langgenius/dify/blob/main/CONTRIBUTING.md) and [Language Policy](https://github.com/langgenius/dify/issues/1542). - [x] This is only for bug report, if you would like to ask a question, please head to [Discussions](https://github.com/langgenius/dify/discussions/categories/general). - [x] I have searched for existing issues [search for existing issues](https://github.com/langgenius/dify/issues), including closed ones. - [x] I confirm that I am using English to submit this report, otherwise it will be closed. - [x] 【中文

Fix

1. Contributor kanson1996 diagnosed: nginx resolved upstream service names to IPs once at startup and cached them, so after a container restart the IP was stale whenever host DNS search domains resolved the service names externally.
2. Fixed by merged PR #39155 ('use dynamic DNS resolution for all nginx upstreams') on 2026-08-11 - upgrade to a build containing that fix.

Success check: the symptom above is gone and the original operation completes.

When to use

• You hit this exact symptom in dify.
• You want the verified fix without digging through the thread.

When not to use

• A different error in dify, even a similar-looking one.
• General dify setup or credential questions.

Compatibility

• Dify (langgenius/dify)

Variant phrasings

• How to fix "fix(docker): nginx caches wrong upstream IP after restart when host DNS search domains resolve service names externally" in dify
• dify: fix(docker): nginx caches wrong upstream IP after restart when host DNS search domains resolve service names externally

Source

• https://github.com/langgenius/dify/issues/39154

In gh:langgenius/dify#39154 (https://github.com/langgenius/dify/issues/39154), someone reported: Issue langgenius/dify#39154 (closed, 60 comments): ### Self Checks - [x] I have read the Contributing Guide and Language Policy. - [x] This is only for bug report, if you would like to ask a question, please head to Discussions. - [x] I have searched for existing issues search for existing issues, including closed ones. - [x] I confirm that I am using English to submit this report, otherwise it will be closed. - [x] 【中文 The verified resolution from the thread: Contributor kanson1996 diagnosed: nginx resolved upstream service names to IPs once at startup and cached them, so after a container restart the IP was stale whenever host DNS search domains resolved the service names externally. Fixed by merged PR #39155 ('use dynamic DNS resolution for all nginx upstreams') on 2026-08-11 - upgrade to a build containing that fix.