Implemet docker update command

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>

integration-cli/docker_api_update_unix_test.go

@@ -0,0 +1,43 @@
+// +build !windows
+
+package main
+
+import (
+	"strings"
+
+	"github.com/docker/docker/pkg/integration/checker"
+	"github.com/go-check/check"
+)
+
+func (s *DockerSuite) TestApiUpdateContainer(c *check.C) {
+	testRequires(c, DaemonIsLinux)
+	testRequires(c, memoryLimitSupport)
+	testRequires(c, swapMemorySupport)
+
+	name := "apiUpdateContainer"
+	hostConfig := map[string]interface{}{
+		"Memory":     314572800,
+		"MemorySwap": 524288000,
+	}
+	dockerCmd(c, "run", "-d", "--name", name, "-m", "200M", "busybox", "top")
+	_, _, err := sockRequest("POST", "/containers/"+name+"/update", hostConfig)
+	c.Assert(err, check.IsNil)
+
+	memory, err := inspectField(name, "HostConfig.Memory")
+	c.Assert(err, check.IsNil)
+	if memory != "314572800" {
+		c.Fatalf("Got the wrong memory value, we got %d, expected 314572800(300M).", memory)
+	}
+	file := "/sys/fs/cgroup/memory/memory.limit_in_bytes"
+	out, _ := dockerCmd(c, "exec", name, "cat", file)
+	c.Assert(strings.TrimSpace(out), checker.Equals, "314572800")
+
+	memorySwap, err := inspectField(name, "HostConfig.MemorySwap")
+	c.Assert(err, check.IsNil)
+	if memorySwap != "524288000" {
+		c.Fatalf("Got the wrong memorySwap value, we got %d, expected 524288000(500M).", memorySwap)
+	}
+	file = "/sys/fs/cgroup/memory/memory.memsw.limit_in_bytes"
+	out, _ = dockerCmd(c, "exec", name, "cat", file)
+	c.Assert(strings.TrimSpace(out), checker.Equals, "524288000")
+}