How to limit IO speed in docker and share file with system in the same time?

Question

Temporarily, I use the -v param like /rootfs/shared_dir:/docker/docker_file.

My container creates some data file in the folder and I want to share the folder with my system.

Also I want to limit the IO speed in the docker container. How can I do this?

Answer 1

After version 1.10 docker added new features to manipulate IO speed in the container.

~$ docker help run | grep -E 'bps|IO'
Usage:  docker run [OPTIONS] IMAGE [COMMAND] [ARG...]
  --blkio-weight                  Block IO (relative weight), between 10 and 1000
  --blkio-weight-device=[]        Block IO weight (relative device weight)
  --device-read-bps=[]            Limit read rate (bytes per second) from a device
  --device-read-iops=[]           Limit read rate (IO per second) from a device
  --device-write-bps=[]           Limit write rate (bytes per second) to a device
  --device-write-iops=[]          Limit write rate (IO per second) to a device

for example if you want to limit write speed to 50 MB/s

$ docker run -it --rm --device-write-bps /dev/sda:50mb ubuntu /bin/bash
root@e88db9cb1263:/# time dd if=/dev/zero of=test.out bs=1M count=1024 oflag=direct
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 20.4334 s, 52.5 MB/s

real    0m20.437s
user    0m0.016s
sys     0m0.472s

without limit my speed is 291 MB/s

~$ docker run -it ubuntu bash
root@2911226bd75e:/# time dd if=/dev/zero of=test.out bs=1M count=1024 oflag=direct
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 3.69373 s, 291 MB/s

real    0m3.696s
user    0m0.004s
sys     0m0.496s