/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.stream.Stream;
 
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone {
    public static void main(String[] args) throws java.lang.Exception {
        System.out.println("Am I running inside docker? " + Ideone.isRunningInsideDocker());
    }
 
    public static Boolean isRunningInsideDocker() {
 
        try (Stream < String > stream =
            Files.lines(Paths.get("/proc/1/cgroup"))) {
            return stream.anyMatch(line -> line.contains("docker"));
        } catch (IOException e) {
            return false;
        }
    }
}

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