Adding integration tests for --cgroup-parent feature.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)

docs/sources/reference/api/docker_remote_api.md

@@ -72,6 +72,10 @@ Added a `RepoDigests` field to include image digest information.
 **New!**
 Builds can now set resource constraints for all containers created for the build.
 
+**New!**
+(`CgroupParent`) can be passed in the host config to setup container cgroups under a specific cgroup.
+
+
 ## v1.17
 
 ### Full Documentation

docs/sources/reference/api/docker_remote_api_v1.18.md

@@ -162,7 +162,8 @@ Create a container
                "NetworkMode": "bridge",
                "Devices": [],
                "Ulimits": [{}],
-               "LogConfig": { "Type": "json-file", Config: {} }
+               "LogConfig": { "Type": "json-file", Config: {} },
+               "CgroupParent": ""
             }
         }
 
@@ -260,6 +261,7 @@ Json Parameters:
         `{ "Type": "<driver_name>", "Config": {"key1": "val1"}}
         Available types: `json-file`, `none`.
         `json-file` logging driver.
+  -   **CgroupParent** - Path to cgroups under which the cgroup for the container will be created. If the path is not absolute, the path is considered to be relative to the cgroups path of the init process. Cgroups will be created if they do not already exist.
 
 Query Parameters:
 

docs/sources/reference/commandline/cli.md

@@ -805,7 +805,7 @@ Creates a new container.
       -c, --cpu-shares=0         CPU shares (relative weight)
       --cap-add=[]               Add Linux capabilities
       --cap-drop=[]              Drop Linux capabilities
-      --cgroup-parent=           Optional parent cgroup for the container
+      --cgroup-parent=""         Optional parent cgroup for the container
       --cidfile=""               Write the container ID to the file
       --cpuset-cpus=""           CPUs in which to allow execution (0-3, 0,1)
       --device=[]                Add a host device to the container

integration-cli/docker_cli_run_unix_test.go

@@ -7,6 +7,7 @@ import (
 	"io/ioutil"
 	"os"
 	"os/exec"
+	"path"
 	"path/filepath"
 	"strings"
 	"testing"
@@ -107,3 +108,81 @@ func TestRunWithUlimits(t *testing.T) {
 
 	logDone("run - ulimits are set")
 }
+
+func getCgroupPaths(test string) map[string]string {
+	cgroupPaths := map[string]string{}
+	for _, line := range strings.Split(test, "\n") {
+		parts := strings.Split(line, ":")
+		if len(parts) != 3 {
+			fmt.Printf("unexpected file format for /proc/self/cgroup - %q", line)
+			continue
+		}
+		cgroupPaths[parts[1]] = parts[2]
+	}
+	return cgroupPaths
+}
+
+func TestRunContainerWithCgroupParent(t *testing.T) {
+	testRequires(t, NativeExecDriver)
+	defer deleteAllContainers()
+
+	cgroupParent := "test"
+	data, err := ioutil.ReadFile("/proc/self/cgroup")
+	if err != nil {
+		t.Fatalf("failed to read '/proc/self/cgroup - %v", err)
+	}
+	selfCgroupPaths := getCgroupPaths(string(data))
+	selfCpuCgroup, found := selfCgroupPaths["cpu"]
+	if !found {
+		t.Fatalf("unable to find self cpu cgroup path. CgroupsPath: %v", selfCgroupPaths)
+	}
+
+	out, _, err := runCommandWithOutput(exec.Command(dockerBinary, "run", "--cgroup-parent", cgroupParent, "--rm", "busybox", "cat", "/proc/self/cgroup"))
+	if err != nil {
+		t.Fatalf("unexpected failure when running container with --cgroup-parent option - %s\n%v", string(out), err)
+	}
+	cgroupPaths := getCgroupPaths(string(out))
+	if len(cgroupPaths) == 0 {
+		t.Fatalf("unexpected output - %q", string(out))
+	}
+	found = false
+	expectedCgroupPrefix := path.Join(selfCpuCgroup, cgroupParent)
+	for _, path := range cgroupPaths {
+		if strings.HasPrefix(path, expectedCgroupPrefix) {
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Fatalf("unexpected cgroup paths. Expected at least one cgroup path to have prefix %q. Cgroup Paths: %v", expectedCgroupPrefix, cgroupPaths)
+	}
+	logDone("run - cgroup parent")
+}
+
+func TestRunContainerWithCgroupParentAbsPath(t *testing.T) {
+	testRequires(t, NativeExecDriver)
+	defer deleteAllContainers()
+
+	cgroupParent := "/cgroup-parent/test"
+
+	out, _, err := runCommandWithOutput(exec.Command(dockerBinary, "run", "--cgroup-parent", cgroupParent, "--rm", "busybox", "cat", "/proc/self/cgroup"))
+	if err != nil {
+		t.Fatalf("unexpected failure when running container with --cgroup-parent option - %s\n%v", string(out), err)
+	}
+	cgroupPaths := getCgroupPaths(string(out))
+	if len(cgroupPaths) == 0 {
+		t.Fatalf("unexpected output - %q", string(out))
+	}
+	found := false
+	for _, path := range cgroupPaths {
+		if strings.HasPrefix(path, cgroupParent) {
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Fatalf("unexpected cgroup paths. Expected at least one cgroup path to have prefix %q. Cgroup Paths: %v", cgroupParent, cgroupPaths)
+	}
+
+	logDone("run - cgroup parent with absolute cgroup path")
+}