usage environment

VirtulBox : 6.1 Host OS: Ubuntu 18.04 Docer : docker-ce 19.03.13

The host OS of docker is a virtual environment running on VirtualBox.

Image execution

When booting CentOS with privileges.

$ sudo docker run -itd --privileged --name PROCESS_NAME IMAGE_NAME /sbin/init
$ sudo docker run -itd --privileged -p 8080:80 --name PROCESS_NAME IMAGE_NAME /sbin/init
↑ When specifying the port, it looks like this

Sudo is not required if the user to be executed is included in the docker group.

Checking the status of the container

Stream

$ sudo docker stats centos8

Do not stream

$ sudo docker stats centos8 --no-stream

Set memory limit after booting

I stumbled in various ways, but succeeded by doing the following.

$ sudo docker update -m 1G --memory-swap -1 CONTAINER_ID

The following things such as stumbling

At first, I executed the following command, but an error occurred.

$ sudo docker update -m 1G CONTAINER_ID
Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.

Solved by changing the swap setting of grub.

$ sudo vi /etc/default/grub
$ sudo update-grub
grub.Update cfg and restart the host OS.

When I re-executed it after restarting, the following error occurred.

$ docker update -m 1G 917f3986a06b
Error response from daemon: Cannot update container 917f3986a06bb9f99b095af4f3e5334ce125f596f9926db2733bdb4d20868b47: Memory limit should be smaller than already set memoryswap limit, update the memoryswap at the same time

So, I set the "--memory-swap -1" option and executed it, and it succeeded.

When the memory is loaded as shown below, it can be confirmed that the 1G limit is applied.

$ docker exec -it centos8 /bin/bash
# /dev/null < `yes`

$ docker stats centos8 --no-stream
CONTAINER ID        NAME                CPU %               MEM USAGE / LIMIT   MEM %               NET I/O             BLOCK I/O           PIDS
917f3986a06b        centos8             106.50%             1GiB / 1GiB         100.00%             15.4kB / 10.4kB     52.3MB / 4.1kB      229

Docker operation memo