Move the capabilities detection into a runtime method

runtime.go

@@ -307,6 +307,27 @@ func (runtime *Runtime) restore() error {
 	return nil
 }
 
+func (runtime *Runtime) UpdateCapabilities(quiet bool) {
+	if cgroupMemoryMountpoint, err := FindCgroupMountpoint("memory"); err != nil {
+		if !quiet {
+			log.Printf("WARNING: %s\n", err)
+		}
+	} else {
+		_, err1 := ioutil.ReadFile(path.Join(cgroupMemoryMountpoint, "memory.limit_in_bytes"))
+		_, err2 := ioutil.ReadFile(path.Join(cgroupMemoryMountpoint, "memory.soft_limit_in_bytes"))
+		runtime.capabilities.MemoryLimit = err1 == nil && err2 == nil
+		if !runtime.capabilities.MemoryLimit && !quiet {
+			log.Printf("WARNING: Your kernel does not support cgroup memory limit.")
+		}
+
+		_, err = ioutil.ReadFile(path.Join(cgroupMemoryMountpoint, "memory.memsw.limit_in_bytes"))
+		runtime.capabilities.SwapLimit = err == nil
+		if !runtime.capabilities.SwapLimit && !quiet {
+			log.Printf("WARNING: Your kernel does not support cgroup swap limit.")
+		}
+	}
+}
+
 // FIXME: harmonize with NewGraph()
 func NewRuntime(autoRestart bool) (*Runtime, error) {
 	runtime, err := NewRuntimeFromDirectory("/var/lib/docker", autoRestart)
@@ -322,23 +343,7 @@ func NewRuntime(autoRestart bool) (*Runtime, error) {
 			log.Printf("WARNING: You are running linux kernel version %s, which might be unstable running docker. Please upgrade your kernel to 3.8.0.", k.String())
 		}
 	}
-
-	if cgroupMemoryMountpoint, err := FindCgroupMountpoint("memory"); err != nil {
-		log.Printf("WARNING: %s\n", err)
-	} else {
-		_, err1 := ioutil.ReadFile(path.Join(cgroupMemoryMountpoint, "memory.limit_in_bytes"))
-		_, err2 := ioutil.ReadFile(path.Join(cgroupMemoryMountpoint, "memory.soft_limit_in_bytes"))
-		runtime.capabilities.MemoryLimit = err1 == nil && err2 == nil
-		if !runtime.capabilities.MemoryLimit {
-			log.Printf("WARNING: Your kernel does not support cgroup memory limit.")
-		}
-
-		_, err = ioutil.ReadFile(path.Join(cgroupMemoryMountpoint, "memory.memsw.limit_in_bytes"))
-		runtime.capabilities.SwapLimit = err == nil
-		if !runtime.capabilities.SwapLimit {
-			log.Printf("WARNING: Your kernel does not support cgroup swap limit.")
-		}
-	}
+	runtime.UpdateCapabilities(false)
 	return runtime, nil
 }
 

runtime_test.go

@@ -93,7 +93,7 @@ func newTestRuntime() (*Runtime, error) {
 	if err != nil {
 		return nil, err
 	}
-
+	runtime.UpdateCapabilities(true)
 	return runtime, nil
 }