Add KernelMemory to "info" and show warning

This change adds "KernelMemory" to the /info endpoint and
shows a warning if KernelMemory is not supported by the kernel.

This makes it more consistent with the other memory-limit
options.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

api/client/info.go

@@ -105,6 +105,9 @@ func (cli *DockerCli) CmdInfo(args ...string) error {
 		if !info.SwapLimit {
 			fmt.Fprintln(cli.err, "WARNING: No swap limit support")
 		}
+		if !info.KernelMemory {
+			fmt.Fprintln(cli.err, "WARNING: No kernel memory limit support")
+		}
 		if !info.OomKillDisable {
 			fmt.Fprintln(cli.err, "WARNING: No oom kill disable support")
 		}

daemon/info.go

@@ -111,6 +111,7 @@ func (daemon *Daemon) SystemInfo() (*types.Info, error) {
 	if runtime.GOOS != "windows" {
 		v.MemoryLimit = sysInfo.MemoryLimit
 		v.SwapLimit = sysInfo.SwapLimit
+		v.KernelMemory = sysInfo.KernelMemory
 		v.OomKillDisable = sysInfo.OomKillDisable
 		v.CPUCfsPeriod = sysInfo.CPUCfsPeriod
 		v.CPUCfsQuota = sysInfo.CPUCfsQuota

docs/reference/api/docker_remote_api.md

@@ -122,6 +122,7 @@ This section lists each version from latest to oldest.  Each listing includes a
 * `POST /containers/(name)/update` now supports updating container's restart policy.
 * `POST /networks/create` now supports enabling ipv6 on the network by setting the `EnableIPv6` field (doing this with a label will no longer work).
 * `GET /info` now returns `CgroupDriver` field showing what cgroup driver the daemon is using; `cgroupfs` or `systemd`.
+* `GET /info` now returns `KernelMemory` field, showing if "kernel memory limit" is supported.
 
 ### v1.22 API changes
 

docs/reference/api/docker_remote_api_v1.23.md

@@ -2161,6 +2161,7 @@ Display system-wide information
         "IndexServerAddress": "https://index.docker.io/v1/",
         "InitPath": "/usr/bin/docker",
         "InitSha1": "",
+        "KernelMemory": true,
         "KernelVersion": "3.12.0-1-amd64",
         "Labels": [
             "storage=ssd"