I have two containers ran by Docker Swarm:
# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
18f1e7d79f5b default/image1:latest "/bin/sh -c 'java ..." 12 hours ago Up 12 hours image1.1.x56zz152kmqtqpxzle5nkbs8r
11d1f05fcff1 default/image2:latest "java -cp /app/sca..." 13 hours ago Up 13 hours image2.1.ljztzeeh8i5r6ebr3n4hcj45e
$ docker stats --no-stream
CONTAINER CPU % MEM USAGE / LIMIT MEM % NET I/O BLOCK I/O PIDS
18f1e7d79f5b 0.92% 0B / 0B 0.00% 648B / 0B 0B / 0B 0
11d1f05fcff1 0.91% 0B / 0B 0.00% 39.9MB / 26.9MB 51.2MB / 0B 0
Host OS is Debian Jessie. There are JVM applications in both containers. Why does docker stats show zero memory usage? Should I configure my Java apps somehow to be able to see memory usage in docker stats? Is there some other way to check memory usage?