Locking for entire focker by default.

focker/focker.py

@@ -38,6 +38,7 @@ from .compose import \
     command_compose_build, \
     command_compose_run
 from .bootstrap import command_bootstrap
+from .misc import focker_lock
 
 
 class ListForwarderFunctor(object):
@@ -203,6 +204,7 @@ def create_parser():
 
 
 def main():
+    focker_lock()
     zfs_init()
     parser = create_parser()
     args = parser.parse_args()

focker/jail.py

@@ -15,8 +15,6 @@ import os
 import jailconf
 from .mount import getmntinfo
 import shlex
-import fcntl
-# import pdb
 import stat
 
 
@@ -38,18 +36,9 @@ def backup_file(fname, nbackups=10):
 
 
 def jail_conf_write(conf):
-    os.makedirs('/var/lock', exist_ok=True)
-    with open('/var/lock/focker.lock', 'a+') as f:
-        print('Waiting for /var/lock/focker.lock ...')
-        fcntl.flock(f, fcntl.LOCK_EX)
-        print('Lock acquired')
-        try:
-            bakname = backup_file('/etc/jail.conf')
-            os.chmod(bakname, 0o600)
-            conf.write('/etc/jail.conf')
-        finally:
-            fcntl.flock(f, fcntl.LOCK_UN)
-            print('Lock released')
+    bakname = backup_file('/etc/jail.conf')
+    os.chmod(bakname, 0o600)
+    conf.write('/etc/jail.conf')
 
 
 def jail_fs_create(image=None):

focker/misc.py

@@ -7,6 +7,8 @@
 
 import random
 from .zfs import zfs_exists
+import os
+import fcntl
 
 
 def random_sha256_hexdigest():
@@ -19,3 +21,20 @@ def find_prefix(head, tail):
         if not zfs_exists(name):
             break
     return name
+
+
+def focker_lock():
+    os.makedirs('/var/lock', exist_ok=True)
+    if focker_lock.fd is None:
+        focker_lock.fd = open('/var/lock/focker.lock', 'a+')
+    print('Waiting for /var/lock/focker.lock ...')
+    fcntl.flock(focker_lock.fd, fcntl.LOCK_EX)
+    print('Lock acquired.')
+focker_lock.fd = None
+
+
+def focker_unlock():
+    if focker_lock.fd is None:
+        return
+    fcntl.flock(focker_lock.fd, fcntl.LOCK_UN)
+    print('Lock released')