Recent change caused Environment variables to no longer work

[xarinatan]

Today when I updated my dockergen container (latest tag), it no longer worked, seemingly not finding the environment variables I have defined anymore.
When I reverted to 0.14 everything worked fine again, so it seems like in image 9209330fbea3 there's a bug that it doesn't read from environment anymore.

I saw these errors that seem to indicate that it's reading the wrong maps for the wrong variables perhaps, but perhaps I'm wrong:

nginx-proxy-gen   | 2025/06/18 16:15:16 unable to find key from the path expression VIRTUAL_HOST in map map[PATH:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin]
nginx-proxy-gen   | 2025/06/18 16:15:16 unable to find key from the path expression VIRTUAL_HOST in map map[ACMESH_VERSION:3.1.1 COMPANION_VERSION:v2.6.0-4-g1fd6385 DHPARAM_GENERATION:false DOCKER_HOST:unix:///var/run/docker.sock PATH:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/app]
[...]
map[LETSENCRYPT_HOST:bashquotes.dragonhive.net NODE_VERSION:18.20.8 PATH:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin VIRTUAL_HOST:bashquotes.dragonhive.net VIRTUAL_PORT:3000 VIRTUAL_PROTO:http YARN_VERSION:1.22.22]
nginx-proxy-gen   | 2025/06/18 16:15:16 unable to find key from the path expression CERT_NAME in map map[LETSENCRYPT_HOST:bashquotes.dragonhive.net NODE_VERSION:18.20.8 PATH:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin VIRTUAL_HOST:bashquotes.dragonhive.net VIRTUAL_PORT:3000 VIRTUAL_PROTO:http YARN_VERSION:1.22.22]

Note the VIRTUAL_HOST is present in the maps of the later errors when it's looking for different variables (like CERT_NAME), but not in the maps when it's looking for the VIRTUAL_HOST variable, so perhaps it's grabbing the wrong ones?

I know about the work to move to labels instead of environment variables but this seemed unrelated (and I also recall it being said they would still support the 'legacy' environment variables for the time being)

[aaccioly]

Likely #682 @buchdag.

[buchdag]

@aaccioly agreed 👍

@xarinatan could your pull the image nginxproxy/docker-gen:revert-682 and validate that it fix the issue ?

[xarinatan]

@aaccioly agreed 👍

@xarinatan could your pull the image nginxproxy/docker-gen:revert-682 and validate that it fix the issue ?

Sorry for the delay, I've been busy and forgot to get back to this. I just gave it a quick test in production (because I'm 🤠 like that) and it seems to work 👍
nice quick find! @aaccioly @buchdag

[buchdag]

@xarinatan I'm actually unable to reproduce the bug on my side, and the nginx-proxy test suite seem to pass just fine with a docker-gen version that include the patch from #682, the one that was supposed to cause the bug 🤷

• could you detail the issues you experienced beside the log warnings ?
• could you provide a reproducible example ?

So far I've seen that #682 mistakenly generate a LOT of undesirable logs, but I did not manage to make it break anything.

[xarinatan]

I've tested the latest tag again and it seems like it works again. Previously it definitely didn't work, the frontend was fully offline while I had those error messages in the log I posted in the original report. I'm not seeing those anymore either.. so maybe something was fixed, or maybe it was a temporary glitch on my side somehow (I did reboot the server at least once since for unrelated updates).

So I guess it can be closed for now, I'll reopen it if the problem happens again (or if anyone else runs into it, feel free to reopen it too).