Skip empty directories on prior graphdriver detection
When starting the daemon, the `/var/lib/docker` directory
is scanned for existing directories, so that the previously
selected graphdriver will automatically be used.
In some situations, empty directories are present (those
directories can be created during feature detection of
graph-drivers), in which case the daemon refuses to start.
This patch improves detection, and skips empty directories,
so that leftover directories don't cause the daemon to
fail.
Before this change:
$ mkdir /var/lib/docker /var/lib/docker/aufs /var/lib/docker/overlay2
$ dockerd
...
Error starting daemon: error initializing graphdriver: /var/lib/docker contains several valid graphdrivers: overlay2, aufs; Please cleanup or explicitly choose storage driver (-s <DRIVER>)
With this patch applied:
$ mkdir /var/lib/docker /var/lib/docker/aufs /var/lib/docker/overlay2
$ dockerd
...
INFO[2017-11-16T17:26:43.207739140Z] Docker daemon commit=ab90bc296 graphdriver(s)=overlay2 version=dev
INFO[2017-11-16T17:26:43.208033095Z] Daemon has completed initialization
And on restart (prior graphdriver is still picked up):
$ dockerd
...
INFO[2017-11-16T17:27:52.260361465Z] [graphdriver] using prior storage driver: overlay2
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Sebastiaan van Stijn authored on 2017/11/17 02:22:22Showing 2 changed files
| ... | ... |
@@ -283,8 +283,27 @@ func scanPriorDrivers(root string) map[string]bool {
|
| 283 | 283 |
for driver := range drivers {
|
| 284 | 284 |
p := filepath.Join(root, driver) |
| 285 | 285 |
if _, err := os.Stat(p); err == nil && driver != "vfs" {
|
| 286 |
- driversMap[driver] = true |
|
| 286 |
+ if !isEmptyDir(p) {
|
|
| 287 |
+ driversMap[driver] = true |
|
| 288 |
+ } |
|
| 287 | 289 |
} |
| 288 | 290 |
} |
| 289 | 291 |
return driversMap |
| 290 | 292 |
} |
| 293 |
+ |
|
| 294 |
+// isEmptyDir checks if a directory is empty. It is used to check if prior |
|
| 295 |
+// storage-driver directories exist. If an error occurs, it also assumes the |
|
| 296 |
+// directory is not empty (which preserves the behavior _before_ this check |
|
| 297 |
+// was added) |
|
| 298 |
+func isEmptyDir(name string) bool {
|
|
| 299 |
+ f, err := os.Open(name) |
|
| 300 |
+ if err != nil {
|
|
| 301 |
+ return false |
|
| 302 |
+ } |
|
| 303 |
+ defer f.Close() |
|
| 304 |
+ |
|
| 305 |
+ if _, err = f.Readdirnames(1); err == io.EOF {
|
|
| 306 |
+ return true |
|
| 307 |
+ } |
|
| 308 |
+ return false |
|
| 309 |
+} |
| 291 | 310 |
new file mode 100644 |
| ... | ... |
@@ -0,0 +1,37 @@ |
| 0 |
+package graphdriver |
|
| 1 |
+ |
|
| 2 |
+import ( |
|
| 3 |
+ "io/ioutil" |
|
| 4 |
+ "os" |
|
| 5 |
+ "path/filepath" |
|
| 6 |
+ "testing" |
|
| 7 |
+ |
|
| 8 |
+ "github.com/stretchr/testify/assert" |
|
| 9 |
+ "github.com/stretchr/testify/require" |
|
| 10 |
+) |
|
| 11 |
+ |
|
| 12 |
+func TestIsEmptyDir(t *testing.T) {
|
|
| 13 |
+ tmp, err := ioutil.TempDir("", "test-is-empty-dir")
|
|
| 14 |
+ require.NoError(t, err) |
|
| 15 |
+ defer os.RemoveAll(tmp) |
|
| 16 |
+ |
|
| 17 |
+ d := filepath.Join(tmp, "empty-dir") |
|
| 18 |
+ err = os.Mkdir(d, 0755) |
|
| 19 |
+ require.NoError(t, err) |
|
| 20 |
+ empty := isEmptyDir(d) |
|
| 21 |
+ assert.True(t, empty) |
|
| 22 |
+ |
|
| 23 |
+ d = filepath.Join(tmp, "dir-with-subdir") |
|
| 24 |
+ err = os.MkdirAll(filepath.Join(d, "subdir"), 0755) |
|
| 25 |
+ require.NoError(t, err) |
|
| 26 |
+ empty = isEmptyDir(d) |
|
| 27 |
+ assert.False(t, empty) |
|
| 28 |
+ |
|
| 29 |
+ d = filepath.Join(tmp, "dir-with-empty-file") |
|
| 30 |
+ err = os.Mkdir(d, 0755) |
|
| 31 |
+ require.NoError(t, err) |
|
| 32 |
+ _, err = ioutil.TempFile(d, "file") |
|
| 33 |
+ require.NoError(t, err) |
|
| 34 |
+ empty = isEmptyDir(d) |
|
| 35 |
+ assert.False(t, empty) |
|
| 36 |
+} |