It is now possible to configure multiple Check_MK agents for a single host.
With this change, you can now configure e.g. a ESX VCenter to use the ESX special agent together with the regular Check_MK agent installed on the monitored host.
All existing hosts remain using their existing configuration after an update. Also new hosts only use a single Check_MK agent using the already existing logic where a) The Check_MK agent was contacted via TCP or b) a configured data source program (special agent or other program invocation) was used.
The new feature can be enabled by changing the host attribute (on hosts or folders) "Check_MK Agent" to e.g. "Contact Check_MK agent and all datasource programs". This will make Check_MK use all data sources matching on this host instead of just picking the first matching one. There is also an alternative option "Use all enabled datasources" available which can be used to execute only the data sources matching the host.
On the way to this change we have changed server previously existing things:
Please note: In case you are using the Web-API calls to create or modify hosts or folders while setting attributes we changed with this change, you may have to change your API calls.