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Large Environments (100k+ Hosts)

The Syncer can manage Checkmk environments with more than 100,000 hosts. Several configuration switches are available to prevent timeouts and reduce memory pressure in these scenarios.

Set all of these in local_config.py.

Timeout Prevention

Variable Description
CMK_COLLECT_BULK_OPERATIONS Separates DB and Checkmk API operations into two phases. Prevents DB cursor timeouts when Checkmk API calls take too long. Requires more RAM.
CMK_GET_HOST_BY_FOLDER Queries hosts from Checkmk folder by folder instead of in one request. Prevents request timeouts caused by retrieving too many hosts at once.

Failed Bulk Requests

Checkmk rejects a complete bulk request as soon as a single entry in it is invalid — for example a host carrying a tag value that does not exist in Checkmk yet. With CMK_BULK_CREATE_OPERATIONS at its default of 300, one broken host takes 299 healthy ones down with it, and they stay unsynchronised until the cause is fixed.

Setting CMK_BULK_FALLBACK_SINGLE = True makes the Syncer send the hosts of a failed batch one by one afterwards, so only the hosts Checkmk actually rejects are lost. The names of those hosts are written to the job log.

It is off by default because it costs one request per host of a failed batch. Two safeguards limit that cost:

  • A request that ran into a timeout is never repeated — Checkmk may have applied it already.
  • If a batch does not get a single host through, the problem is Checkmk itself rather than one broken entry, and the Syncer stops retrying for the rest of the run.

Object Type Limiting

If you have multiple object types in the Syncer database (hosts, applications, contacts, etc.), operations that only need to process hosts do not need to iterate over all other objects. Limiting by object type happens at the database level and is significantly faster than using standard filter rules.

To configure it:

  1. Open the Checkmk account in the Syncer
  2. Add a Plugin Setting
  3. Select the operation you want to limit (e.g. export_hosts)
  4. Select the object types to include

This setting applies to all commands using that account.

Checkmk Version Compatibility

For Checkmk 2.2 environments, set:

config = {
    'CMK_SUPPORT': '2.2',
}

See Local Config Variables for all Checkmk-specific config options.