[enh] Prevent non-updated multi-instances apps installation (close #126)

locales/en.json

@@ -34,6 +34,8 @@
     "app_extraction_failed" : "Unable to extract installation files",
     "app_install_files_invalid" : "Invalid installation files",
     "app_manifest_invalid" : "Invalid app manifest",
+    "app_incompatible" : "The app is incompatible with your YunoHost version",
+    "app_package_need_update" : "The app package need to be updated to follow YunoHost changes",
     "app_argument_choice_invalid" : "Invalid choice for argument '{name:s}', it must be one of {choices:s}",
     "app_argument_invalid" : "Invalid value for argument '{name:s}': {error:s}",
     "app_argument_required" : "Argument '{name:s}' is required",

src/yunohost/app.py

@@ -1385,12 +1385,24 @@ def _encode_string(value):
 def _check_manifest_requirements(manifest):
     """Check if required packages are met from the manifest"""
     requirements = manifest.get('requirements', dict())
+
     # FIXME: Deprecate min_version key
     if 'min_version' in manifest:
         requirements['yunohost'] = '>> {0}'.format(manifest['min_version'])
         logger.debug("the manifest key 'min_version' is deprecated, "
                      "use 'requirements' instead.")
-    if not requirements:
+
+    # Validate multi-instance app
+    if manifest.get('multi_instance', False):
+        # Handle backward-incompatible change introduced in yunohost >= 2.3.6
+        # See https://dev.yunohost.org/issues/156
+        yunohost_req = requirements.get('yunohost', None)
+        if (not yunohost_req or
+                not packages.SpecifierSet(yunohost_req) & '>= 2.3.6'):
+            raise MoulinetteError(errno.EINVAL, '{0}{1}'.format(
+                m18n.g('colon', m18n.n('app_incompatible')),
+                m18n.n('app_package_need_update')))
+    elif not requirements:
         return
 
     logger.info(m18n.n('app_requirements_checking'))