Limit memory on a Docker container doesn't work

Question

I am running the last version of Docker on top of Ubuntu 13.04 (Raring Ringtail):

root@docker:~# docker version
Client version: 0.6.6
Go version (client         


        

Answer 1

The -m switch does work (setting hard memory limit), and accepts human-readable k|m|g memory units.

You can use docker inspect to verify it has desired effect on the "Memory" key:

$ docker run --rm -d --name ubuntu -m 8g ubuntu:focal && docker inspect ubuntu | grep Memory
            "Memory": 8589934592,
            "KernelMemory": 0,
            "KernelMemoryTCP": 0,
            "MemoryReservation": 0,
            "MemorySwap": -1,
            "MemorySwappiness": null,

$ docker run --rm -d --name ubuntu -m 16g ubuntu:focal && docker inspect ubuntu | grep Memory
            "Memory": 17179869184,
            "KernelMemory": 0,
            "KernelMemoryTCP": 0,
            "MemoryReservation": 0,
            "MemorySwap": -1,
            "MemorySwappiness": null,

You can also set burstable limits, i.e. memory requests / reservations / guaranteed minimums (that won't protect the host from crashing, but will protect the containerized app from running out of memory, until the physical limit is reached):

$ docker run --rm -d --name ubuntu --memory-reservation 16g ubuntu:focal && docker inspect ubuntu | grep Memory
            "Memory": 0,
            "KernelMemory": 0,
            "KernelMemoryTCP": 0,
            "MemoryReservation": 17179869184,
            "MemorySwap": 0,
            "MemorySwappiness": null,