Merge pull request #7391 from Icinga/feature/cluster-sync-avoid-non-utf-8

Cluster sync: Only sync valid UTF8 content (text config, no binaries)

diff --combined doc/16-upgrading-icinga-2.md
index 6eaec877dfd8b3d50bc3cfec6fd198f3473a5fd4,e73d5e5bfd4e206cd140a98bbdedc4f28d29cb6f..5ffbc7fceb08969d956d898cb1dc6b658b228813
--- 1/doc/16-upgrading-icinga-2.md
--- 2/doc/16-upgrading-icinga-2.md
+++ b/doc/16-upgrading-icinga-2.md
@@@ -172,6 -172,15 +172,15 @@@ Since the config sync change detection 
  with anything else than syncing configuration text files. Syncing binary
  files were never supported, but rumors say that some users do so.
  
+ This is now prohibited and logged.
+ 
+ ```
+ [2019-08-02 16:03:19 +0200] critical/ApiListener: Ignoring file '/etc/icinga2/zones.d/global-templates/forbidden.exe' for cluster config sync: Does not contain valid UTF8. Binary files are not supported.
+ Context:
+       (0) Creating config update for file '/etc/icinga2/zones.d/global-templates/forbidden.exe'
+       (1) Activating object 'api' of type 'ApiListener'
+ ```
+ 
  Such binaries wrapped into JSON-RPC cluster messages may always cause changes
  and trigger reload loops. In order to prevent such harm in production,
  use infrastructure tools such as Foreman, Puppet, Ansible, etc. to install
@@@ -289,12 -298,6 +298,12 @@@ It will also attempt to fix them, the f
  
  If you still encounter problems, please follow [this troubleshooting entry](15-troubleshooting.md#troubleshooting-api-missing-runtime-objects).
  
 +### DB IDO MySQL Schema <a id="upgrading-to-2-11-db-ido"></a>
 +
 +The schema for MySQL contains an optional update which
 +drops unneeded indexes. You don't necessarily need to apply
 +this update.
 +
  ### Documentation <a id="upgrading-to-2-11-documentation"></a>
  
  * `Custom attributes` have been renamed to `Custom variables` following the name `vars` and their usage in backends and web interfaces.