Allow one to define Dovecot's schemes in settings

modoboa/core/password_hashers/__init__.py

@@ -2,6 +2,7 @@
 Password hashers for Modoboa.
 """
 
+from django.conf import settings
 from django.utils.encoding import smart_text
 
 from modoboa.core.password_hashers.advanced import (  # NOQA:F401
@@ -32,17 +33,21 @@ def get_password_hasher(scheme):
 
 
 def get_dovecot_schemes():
-    """Return schemes supported by dovecot"""
-    supported_schemes = None
-    try:
-        _, schemes = doveadm_cmd("pw -l")
-    except OSError:
-        pass
-    else:
-        supported_schemes = ["{{{}}}".format(smart_text(scheme))
-                             for scheme in schemes.split()]
+    """Return schemes supported by Dovecot.
 
-    if not supported_schemes:
-        supported_schemes = ['{MD5-CRYPT}', '{PLAIN}']
+    It first try to get supported schemes fron the settings, then from the
+    doveadm output, and fallback to {MD5-CRYPT} and {PLAIN} if the command
+    is not found.
 
-    return supported_schemes
+    :return: A list of supported '{SCHEME}'
+    """
+    schemes = getattr(settings, "DOVECOT_SUPPORTED_SCHEMES", None)
+
+    if not schemes:
+        try:
+            _, schemes = doveadm_cmd("pw -l")
+        except OSError:
+            schemes = "MD5-CRYPT PLAIN"
+
+    return ["{{{}}}".format(smart_text(scheme))
+            for scheme in schemes.split()]

modoboa/core/tests/test_authentication.py

@@ -173,7 +173,7 @@ class AuthenticationTestCase(ModoTestCase):
 
     @override_settings(DOVEADM_LOOKUP_PATH=[DOVEADM_TEST_PATH])
     def test_dovecot_supported_schemes(self):
-        """Validate dovecot supported schemes with fake output."""
+        """Validate Dovecot supported schemes with fake command output."""
         supported_schemes = get_dovecot_schemes()
         self.assertEqual(supported_schemes,
                          ["{MD5}",
@@ -207,6 +207,12 @@ class AuthenticationTestCase(ModoTestCase):
                           "{SHA256-CRYPT}",
                           "{SHA512-CRYPT}"])
 
+    @override_settings(DOVECOT_SUPPORTED_SCHEMES="SHA1 SHA512-CRYPT")
+    def test_dovecot_supported_schemes_from_settings(self):
+        """Validate dovecot supported schemes from the settings."""
+        supported_schemes = get_dovecot_schemes()
+        self.assertEqual(supported_schemes, ["{SHA1}", "{SHA512-CRYPT}"])
+
     def test_dovecot_default_schemes(self):
         """Check default scheme if doveadm is not found."""
         supported_schemes = get_dovecot_schemes()