Improve import error handling for ACME modules

changelogs/fragments/519-acme-cryptography.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - "acme_* modules - improve feedback when importing ``cryptography`` does not work (https://github.com/ansible-collections/community.crypto/issues/518, https://github.com/ansible-collections/community.crypto/pull/519)."

plugins/module_utils/acme/acme.py

@@ -27,6 +27,8 @@
 
 from ansible_collections.community.crypto.plugins.module_utils.acme.backend_cryptography import (
     CryptographyBackend,
+    CRYPTOGRAPHY_ERROR,
+    CRYPTOGRAPHY_MINIMAL_VERSION,
     CRYPTOGRAPHY_VERSION,
     HAS_CURRENT_CRYPTOGRAPHY,
 )
@@ -399,8 +401,19 @@ def create_backend(module, needs_acme_v2):
 
     # Create backend object
     if backend == 'cryptography':
+        if CRYPTOGRAPHY_ERROR is not None:
+            # Either we couldn't import cryptography at all, or there was an unexpected error
+            if CRYPTOGRAPHY_VERSION is None:
+                msg = missing_required_lib('cryptography')
+            else:
+                msg = 'Unexpected error while preparing cryptography: {0}'.format(CRYPTOGRAPHY_ERROR.splitlines()[-1])
+            module.fail_json(msg=msg, exception=CRYPTOGRAPHY_ERROR)
         if not HAS_CURRENT_CRYPTOGRAPHY:
-            module.fail_json(msg=missing_required_lib('cryptography'))
+            # We could import cryptography, but an too old version.
+            module.fail_json(
+                msg='Found cryptography, but only version {0}. {1}'.format(
+                    CRYPTOGRAPHY_VERSION,
+                    missing_required_lib('cryptography >= {0}'.format(CRYPTOGRAPHY_MINIMAL_VERSION))))
         module.debug('Using cryptography backend (library version {0})'.format(CRYPTOGRAPHY_VERSION))
         module_backend = CryptographyBackend(module)
     elif backend == 'openssl':

plugins/module_utils/acme/backend_cryptography.py

@@ -14,6 +14,7 @@
 import datetime
 import os
 import sys
+import traceback
 
 from ansible.module_utils.common.text.converters import to_bytes, to_native, to_text
 
@@ -48,6 +49,9 @@
     extract_first_pem,
 )
 
+CRYPTOGRAPHY_MINIMAL_VERSION = '1.5'
+
+CRYPTOGRAPHY_ERROR = None
 try:
     import cryptography
     import cryptography.hazmat.backends
@@ -60,13 +64,18 @@
     import cryptography.hazmat.primitives.serialization
     import cryptography.x509
     import cryptography.x509.oid
-    CRYPTOGRAPHY_VERSION = cryptography.__version__
-    HAS_CURRENT_CRYPTOGRAPHY = (LooseVersion(CRYPTOGRAPHY_VERSION) >= LooseVersion('1.5'))
-    if HAS_CURRENT_CRYPTOGRAPHY:
-        _cryptography_backend = cryptography.hazmat.backends.default_backend()
-except Exception as dummy:
+except ImportError as dummy:
     HAS_CURRENT_CRYPTOGRAPHY = False
     CRYPTOGRAPHY_VERSION = None
+    CRYPTOGRAPHY_ERROR = traceback.format_exc()
+else:
+    CRYPTOGRAPHY_VERSION = cryptography.__version__
+    HAS_CURRENT_CRYPTOGRAPHY = (LooseVersion(CRYPTOGRAPHY_VERSION) >= LooseVersion(CRYPTOGRAPHY_MINIMAL_VERSION))
+    try:
+        if HAS_CURRENT_CRYPTOGRAPHY:
+            _cryptography_backend = cryptography.hazmat.backends.default_backend()
+    except Exception as dummy:
+        CRYPTOGRAPHY_ERROR = traceback.format_exc()
 
 
 if sys.version_info[0] >= 3: