Remove lock existence checks when creating pods/containers

Given that we don't have a good way of cleaning up locks, these
could potential cause issues if we ever reuse a container or pod
ID

Also changes locks dir to use tmpfs, as we can't directly clean
up locks

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>

Closes: #138
Approved by: rhatdan

libpod/container.go

@@ -430,11 +430,6 @@ func newContainer(rspec *spec.Spec, lockDir string) (*Container, error) {
 
 	// Path our lock file will reside at
 	lockPath := filepath.Join(lockDir, ctr.config.ID)
-	// Ensure there is no conflict - file does not exist
-	_, err := os.Stat(lockPath)
-	if err == nil || !os.IsNotExist(err) {
-		return nil, errors.Wrapf(ErrCtrExists, "lockfile for container ID %s already exists", ctr.config.ID)
-	}
 	// Grab a lockfile at the given path
 	lock, err := storage.GetLockfile(lockPath)
 	if err != nil {

libpod/pod.go

@@ -1,7 +1,6 @@
 package libpod
 
 import (
-	"os"
 	"path/filepath"
 
 	"github.com/containers/storage"
@@ -57,11 +56,6 @@ func newPod(lockDir string) (*Pod, error) {
 
 	// Path our lock file will reside at
 	lockPath := filepath.Join(lockDir, pod.id)
-	// Ensure there is no conflict - file does not exist
-	_, err := os.Stat(lockPath)
-	if err == nil || !os.IsNotExist(err) {
-		return nil, errors.Wrapf(ErrCtrExists, "lockfile for pod ID %s already exists", pod.id)
-	}
 	// Grab a lockfile at the given path
 	lock, err := storage.GetLockfile(lockPath)
 	if err != nil {

libpod/runtime.go

@@ -138,7 +138,7 @@ func NewRuntime(options ...RuntimeOption) (runtime *Runtime, err error) {
 	}
 
 	// Make a directory to hold container lockfiles
-	lockDir := filepath.Join(runtime.config.StaticDir, "lock")
+	lockDir := filepath.Join(runtime.config.TmpDir, "lock")
 	if err := os.MkdirAll(lockDir, 0755); err != nil {
 		// The directory is allowed to exist
 		if !os.IsExist(err) {