Environment variables are not bound properly when unknown fields are not ignored

[wujek-srujek]

When deploying to Cloud Foundry, the embedded web server (Undertow in my case) must use the port defined in the PORT env variable. Simply deploying the repackaged jar to CF used to work for M2.
After an upgrade to M3, Undertow always starts on its default port 8080, which results in an error: 'Instance (index 0) failed to start accepting connections'. This issue is caused by CF checking if the application listens on the port it defined for it, and if it doesn't, it's an error and the app is killed.
I'm not sure if this is a Boot issue, or maybe Undertow's (I think M3 upgrades Untertow, among others).

[wilkinsona]

Thanks for the report. The Java build pack maps the PORT environment variable to the SERVER_PORT environment variable.

Running the Undertow sample:

• java -DSERVER_PORT=8888 -jar target/spring-boot-sample-undertow-1.3.0.M3.jar uses 8080
• java -Dserver.port=8888 -jar target/spring-boot-sample-undertow-1.3.0.M3.jar uses 8888

This looks like a Boot issue to me.

[wilkinsona]

DefaultPropertyNamePatternsMatcher is created with a single name (server), two delimiters (_ and .) and ignoreCase set to false. This causes it to consider SERVER_PORT as not matching so it's not included in the property values used for the binding.