Kernel memory is not allowed to be updated if container is
running, it's not actually a precise kernel limitation.
Before kernel version 4.6, kernel memory will not be accounted
until kernel memory limit is set, if a container created with
kernel memory initialized, kernel memory is accounted as soon
as process created in container, so kernel memory limit update
is allowed afterward. If kernel memory is not initialized,
kernel memory consumed by processes in container will not be
accounted, so we can't update the limit because the account
will be wrong.
So update kernel memory of a running container with kernel memory
initialized is allowed, we should soften the limitation by docker.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
1. Replace raw `docker inspect -f xxx` with `inspectField`, to make code
cleaner and more consistent
2. assert the error in function `inspectField*` so we don't need to
assert the return value of it every time, this will make inspect easier.
Signed-off-by: Zhang Wei <zhangwei555@huawei.com>
When a container create with -m 100m and then docker update other
cgroup settings such as --cpu-quota, the memory limit show by
docker stats will become the default value but not the 100m.
Signed-off-by: Lei Jitang <leijitang@huawei.com>
It's used for updating properties of one or more containers, we only
support resource configs for now. It can be extended in the future.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Qiang Huang