Set Folders and Host Attributes

These rules control how hosts are exported to Checkmk: which folder they land in, which attributes they carry, and special behaviors like cluster creation or opt-outs.

Go to: Modules → Checkmk → Set Folder and Attributes of Host

Folder-based rules stack automatically. All folder outcomes across all matching rules are combined in sort order to produce a nested folder path like /this/is/my/folder. Use the Last Match option on rules to stop evaluation after the first match and avoid unexpected stacking.

Available Actions

Action	Description
Move to Folder	Move the host to a folder. Supports full Jinja — variables that do not match cause the rule to be skipped.
Folder by Attribute Name	Use the attribute key as the folder name, selected by attribute value.
Pool Folder	Assign host to a Folder Pool. Optionally restrict to specific pool names (comma-separated). See Folder Pools.
CMK Attribute by Syncer Attribute	Export a Syncer attribute to Checkmk under the same or a mapped attribute name.
Custom CMK Attributes	Create a key:value attribute. Use {{HOSTNAME}} as placeholder. Separate multiple values with \|\|.
Remove given Attribute if not assigned	Remove specified Checkmk attributes if no other Syncer rule sets them for this host.
Cluster	Create the host as a Cluster. Specify which attributes contain the node names (comma-separated, wildcard * supported).
Parents	Set the host parent. Jinja supported.
Move Optout	Host is never moved to another folder after initial creation.
Update Optout	Host attributes are never updated after initial creation.
Create Optout	Host is not created in Checkmk, but its attributes are updated if it already exists.
Prefix Labels	Every exported label gets the configured prefix.
Update only Prefixed Labels	Only labels with the given prefix are changed by the Syncer.
Dont update prefixed Labels	Labels with the given prefix are never touched by the Syncer.

Write Status Back (CMK_WRITE_STATUS_BACK)

When CMK_WRITE_STATUS_BACK is enabled in local_config.py, the Syncer writes the Checkmk existence status of each host back into the Syncer host inventory after every export run:

'CMK_WRITE_STATUS_BACK': True

For every host processed during a sync, the Syncer sets the inventory key checkmk_status:

Attribute	Type	Description
is_existing	boolean	True if the host exists in Checkmk, False if not

Access this value in conditions and Jinja templates as cmk__is_existing.

Custom Folder Attributes

The Syncer creates all required folders automatically. You can set Checkmk folder attributes — including the visible title — by appending them after a pipe character in the folder name.

Hardcoded folder with attributes:

/my_folder | {'title': 'My Nice Title', 'tag_something': 'value'}

Jinja-based folder name with attributes:

/{{my_jinja_var}} | {'title': 'My Nice Title', 'tag_something': 'value'}

Jinja in the attributes as well:

/{{my_jinja_var}} | {'title': '{{var_containing_title}}', 'tag_something': 'value'}

The pipe syntax is separate from the Jinja syntax — note where the pipe is placed relative to the closing }}.

Contact Groups and WATO Permissions

Contact groups are just another folder attribute, named contactgroups. Its value is a dict: groups holds the list of contact groups and use grants those groups permission on the folder (WATO permissions).

/{{customer}} | {'contactgroups': {'groups': ['team_{{customer}}'], 'use': True}}

Optional flags inside contactgroups:

Flag	Meaning
use	Add these contact groups to the hosts in this folder.
recurse_use	Also add the groups as contacts to the hosts in all sub-folders.
recurse_perms	Also grant permission on all sub-folders.

This assigns the groups on the folder. To have the Syncer create the group objects themselves from host attributes, see Manage Contact Groups.

Merging when hosts share a folder

Several hosts can land in the same folder while each brings its own contact groups — for example one rule per customer adding team_a, another adding team_b, both resolving to the same folder. In that case the Syncer unions the groups lists (duplicates removed), so the folder ends up with the contact groups of all its hosts:

Host A → /shared | {'contactgroups': {'groups': ['team_a'], 'use': True}}
Host B → /shared | {'contactgroups': {'groups': ['team_b'], 'use': True}}

Result folder /shared → contactgroups.groups = ['team_a', 'team_b']

Scalar options such as title or site cannot be merged — two hosts cannot pick one title — so the first host to reach the folder wins for those. The Syncer is the source of truth for the merged group list: it replaces whatever contact groups are currently set on that folder in Checkmk. If you manage some folders' contact groups by hand in Checkmk, do not also set them via a folder option.