Improve container detection if current process is pid 1

[maxxedev]

If current process is pid 1, read directly from System.getenv() instead of performing file i/o on /proc/1/environ

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[ppkarwasz]

@maxxedev,

Can you explain in what consists the improvement? AFAIK the JVM will never have PID 1. Even if it does, checking /proc/1/environ and the environment of the JVM is equivalent.

[maxxedev]

@ppkarwasz

JVM will never have PID 1

JVM can certainly be PID 1 inside a container. Example:

$ cat App.java
public class App {

        public static void main(String... args) {
                var mxBean = java.lang.management.ManagementFactory.getRuntimeMXBean();
                System.out.println(mxBean.getName());
        }
}

$ docker run -it --entrypoint java -v `pwd`:/tmp/ openjdk:21 /tmp/App.java
1@afecfa5e25bb

 

checking /proc/1/environ and the environment of the JVM is equivalent.

Yes, equivalent but perhaps reading from System.getenv() is a slight improvement by avoiding file i/o on procfs

[ppkarwasz]

JVM will never have PID 1

JVM can certainly be PID 1 inside a container. Example:

Point taken.

checking /proc/1/environ and the environment of the JVM is equivalent.

Yes, equivalent but perhaps reading from System.getenv() is a slight improvement by avoiding file i/o on procfs

Your code requires the java.management Java module to handle a specific case that was already handled correctly by the previous code (which only requires java.base). IMHO this is not an improvement.