Runtime constraints on resources

It may be useful to restrict the Docker container usage of resources when running. Docker gives you a many possibilities to set constraints on the memory, CPU usage or disk access usage. Let's begin with setting the memory constraints.

Memory

It's worth knowing that, by default, that is, if you use the default settings without any constraints, the running container can use all of the host memory. To change this behavior we can use the --memory (or -m for short) switch for the docker run command. It takes the usual suffixes k, m, or g for kilobytes, megabytes and gigabytes, respectively.

The syntax of the docker run command with memory constraints set will be as follows:

$ docker run -it -m 512m ubuntu

The preceding command will execute the Ubuntu image with the maximum memory that can be used by the container of half of a gigabyte.

Note

If you do not set the limit on memory that the container can allocate, this can lead to random issues where a single container...