[refactor] fail gracefully if some modules not present

this allows for better modularization in, for instance, the debian
package. we should be able to install just the submodules for the vpn
service, or the mail service.

a better modularization needs the mail_services under core to be moved
to bitmask.mail, and do the switch in the main service module for
bitmask daemon.

3 files changed, 44 insertions, 15 deletions

diff --git a/src/leap/bitmask/cli/keys.py b/src/leap/bitmask/cli/keys.py
index 12191a5d..82de3868 100644
--- a/src/leap/bitmask/cli/keys.py
+++ b/src/leap/bitmask/cli/keys.py
@@ -23,7 +23,12 @@ import sys
 from colorama import Fore
 
 from leap.bitmask.cli import command
-from leap.bitmask.keymanager.validation import ValidationLevels
+
+try:
+    from leap.bitmask.keymanager.validation import ValidationLevels
+    HAS_KM = True
+except ImportError:
+    HAS_KM = False
 
 
 class Keys(command.Command):
diff --git a/src/leap/bitmask/core/mail_services.py b/src/leap/bitmask/core/mail_services.py
index 9c34c120..20d6a342 100644
--- a/src/leap/bitmask/core/mail_services.py
+++ b/src/leap/bitmask/core/mail_services.py
@@ -33,19 +33,31 @@ from twisted.logger import Logger
 
 from leap.common.events import catalog, emit_async
 from leap.common.files import check_and_fix_urw_only
-from leap.bitmask.mua import pixelizer
-from leap.bitmask.hooks import HookableService
+
 from leap.bitmask.bonafide import config
-from leap.bitmask.keymanager import KeyManager
-from leap.bitmask.keymanager.errors import KeyNotFound
-from leap.bitmask.keymanager.validation import ValidationLevels
-from leap.bitmask.mail.constants import INBOX_NAME
-from leap.bitmask.mail.mail import Account
-from leap.bitmask.mail.imap import service as imap_service
-from leap.bitmask.mail.smtp import service as smtp_service
-from leap.bitmask.mail.incoming.service import IncomingMail
-from leap.bitmask.mail.incoming.service import INCOMING_CHECK_PERIOD
+from leap.bitmask.hooks import HookableService
 from leap.bitmask.util import get_gpg_bin_path, merge_status
+
+try:
+    from leap.bitmask.keymanager import KeyManager
+    from leap.bitmask.keymanager.errors import KeyNotFound
+    from leap.bitmask.keymanager.validation import ValidationLevels
+    from leap.bitmask.mail.constants import INBOX_NAME
+    from leap.bitmask.mail.mail import Account
+    from leap.bitmask.mail.imap import service as imap_service
+    from leap.bitmask.mail.smtp import service as smtp_service
+    from leap.bitmask.mail.incoming.service import IncomingMail
+    from leap.bitmask.mail.incoming.service import INCOMING_CHECK_PERIOD
+    HAS_MAIL = True
+except ImportError:
+    HAS_MAIL = False
+
+try:
+    from leap.bitmask.mua import pixelizer
+    HAS_MUA = True
+except ImportError:
+    HAS_MUA = False
+
 from leap.soledad.client.api import Soledad
 
 from leap.bitmask.core.uuid_map import UserMap
@@ -628,7 +640,7 @@ class StandardMailService(service.MultiService, HookableService):
     def _maybe_start_pixelated(self, passthrough, userid, soledad, keymanager):
         incoming = self.getServiceNamed('incoming_mail')
         account = incoming.getServiceNamed(userid).account
-        if pixelizer.HAS_PIXELATED:
+        if HAS_MUA and pixelizer.HAS_PIXELATED:
             pixelizer.start_pixelated_user_agent(
                 userid, soledad, keymanager, account)
         return passthrough
@@ -646,6 +658,9 @@ class IMAPService(service.Service):
         super(IMAPService, self).__init__()
 
     def startService(self):
+        if not HAS_MAIL:
+            self.log.info('Mail module not found')
+            return
         self.log.info('Starting IMAP Service')
         port, factory = imap_service.run_service(
             self._soledad_sessions, factory=self._factory)
@@ -686,6 +701,9 @@ class SMTPService(service.Service):
         super(SMTPService, self).__init__()
 
     def startService(self):
+        if not HAS_MAIL:
+            self.log.info('Mail module not found')
+            return
         self.log.info('starting smtp service')
         port, factory = smtp_service.run_service(
             self._soledad_sessions,
diff --git a/src/leap/bitmask/core/service.py b/src/leap/bitmask/core/service.py
index 6244b17e..ec3536f2 100644
--- a/src/leap/bitmask/core/service.py
+++ b/src/leap/bitmask/core/service.py
@@ -35,8 +35,13 @@ from leap.bitmask.core import flags
 from leap.bitmask.core import _zmq
 from leap.bitmask.core import _session
 from leap.bitmask.core.web.service import HTTPDispatcherService
-from leap.bitmask.vpn.service import VPNService
 from leap.common.events import server as event_server
+try:
+    from leap.bitmask.vpn.service import VPNService
+    HAS_VPN = True
+except ImportError:
+    HAS_VPN = False
+
 
 backend = flags.BACKEND
 
@@ -201,7 +206,8 @@ class BitmaskBackend(configurable.ConfigurableService):
         self._maybe_init_service('mail', service, self.basedir)
 
     def _init_vpn(self):
-        self._maybe_init_service('vpn', VPNService)
+        if HAS_VPN:
+            self._maybe_init_service('vpn', VPNService)
 
     def _init_zmq(self):
         zs = _zmq.ZMQServerService(self)