Docker container 动态修改内存限制

docker动态修改配置用docker update,用法：

docker update -h
Flag shorthand -h has been deprecated, please use --help

Usage:	docker update [OPTIONS] CONTAINER [CONTAINER...]

Update configuration of one or more containers

Options:
      --blkio-weight uint16         Block IO (relative weight), between 10 and 1000, or 0 to disable (default 0)
      --cpu-period int              Limit CPU CFS (Completely Fair Scheduler) period
      --cpu-quota int               Limit CPU CFS (Completely Fair Scheduler) quota
      --cpu-rt-period int           Limit the CPU real-time period in microseconds
      --cpu-rt-runtime int          Limit the CPU real-time runtime in microseconds
  -c, --cpu-shares int              CPU shares (relative weight)
      --cpuset-cpus string          CPUs in which to allow execution (0-3, 0,1)
      --cpuset-mems string          MEMs in which to allow execution (0-3, 0,1)
      --help                        Print usage
      --kernel-memory string        Kernel memory limit
  -m, --memory string               Memory limit
      --memory-reservation string   Memory soft limit
      --memory-swap string          Swap limit equal to memory plus swap: '-1' to enable unlimited swap
      --restart string              Restart policy to apply when a container exits

当前要做的是把一个运行着gitlab 的容器内存限制在2048M以内，尝试用:
docker update -m 2048m gitlab

报错：

Memory limit should be smaller than already set memoryswap limit, update the memoryswap at the same time

发现问题，docker 默认没有启用memory-swap交换内存，直接设置了内存问题会出问题，也就是说宿主 swap 支持使用多少则容器即可使用多少，如果 –memory-swap 设置小于 –memory则设置不生效。

将memory-swap 设置值为 -1，表示容器程序使用内存受限，而 swap 空间使用不受限制。

docker update --memory 2048m --memory-swap -1 gitlab

问题解决。