Masterfiles Policy Framework

Table of Contents

The Masterfiles Policy Framework or MPF also commonly reffered to as simply masterfiles is the policy framework that ships with CFEngine.

The Masterfiles Policy Framework is the default policy that ships with both the CFEngine Enterprise and Community editions. The MPF includes policy to manage cfengine itself, the stdlib, and policy to inventory various aspects of the system.

Overview

The MPF is continually updated. You can track its development on github.

Configuration

The most common controls reference variables in the def bundle in order to keep the modifications to the distributed policy contained within a single place. The recommended way to set classes and define variables in the def bundle is using an augments file. Keeping the modifications to the distributed policy set makes policy framework upgrades significantly easier.

Note: If you need to make modification to a shipped file consider opening a pull request to expose the tunable into the def bundle.

Note: controls/def.cf contains the defaults and settings for promises.cf and controls/update_def.cf contains the defaults and settings for update.cf.

Update Policy (update.cf)

Synchronizing clients with the policy server happens here, in update.cf. Its main job is to copy all the files on the policy server (usually the hub) under $(sys.masterdir) (usually /var/cfengine/masterfiles) to the local host into $(sys.inputdir) (usually /var/cfengine/inputs).

This file should rarely if ever change. Should you ever change it (or when you upgrade CFEngine), take special care to ensure the old and the new CFEngine can parse and execute this file successfully. If not, you risk losing control of your system (that is, if CFEngine cannot successfully execute update.cf, it has no mechanism for distributing new policy files).

By default, the policy defined in update.cf is executed at the beginning of a cf-execd scheduled agent run (see schedule and exec_command as defined in body executor control in controls/cf_execd.cf). When the update policy completes (regardless of success or failure) the policy defined in promises.cf is activated.

This is a standalone policy file. You can actually run it with cf-agent -KI -f ./update.cf but if you don't understand what that command does, please hold off until you've gone through the CFEngine documentation. The contents of update.cf duplicate other things under lib sometimes, in order to be completely standalone.

To repeat, when update.cf is broken, things go bonkers. CFEngine will try to run a backup failsafe.cf you can find in the C core under libpromises/failsafe.cf (that .cf file is written into the C code and can't be modified). If things get to that point, you probably have to look at why corrupted policies made it into production.

As is typical for CFEngine, the policy and the configuration are mixed. In controls/update_def.cf you'll find some very useful settings. Keep referring to controls/update_def.cf as you read this. We are skipping the nonessential ones.

Verify update transfers

Enable additional verrification after file transfers during policy update by defining the class cfengine_internal_verify_update_transfers. When this class is defined, the update policy will hash the transfered file and compare it against the hash given by the server

This augments file will enable this behavior for all clients.

{
  "classes": {
    "cfengine_internal_verify_update_transfers": [ "any" ]
  }
}

Encrypted transfers

Note: When using protocol version 2 or greater all communications are encapsulated within a TLS session. This configuration option is only relevant for clients using protocol version 1 (default for versions 3.6 and prior).

To enable encryption during policy updates define the class cfengine_internal_encrypt_transfers.

Preserve permissions

By default the MPF enforces restrictive permissions for inputs. If the class cfengine_internal_preserve_permissions is defined the permissions of the policy server's masterfiles will be preserved when they are copied.

Enable CFEngine Enterprise HA

When the enable_cfengine_enterprise_hub_ha class is defined the policy to manage High Availability of Enterprise Hubs is enabled.

Note: This class is not defined by default.

Disable cf_promises_validated check

For non policy hubs the default update policy only performs a full scan of masterfiles if cf_promises_validated is repaired. This repair indicates that the hub has validated new policy that the client needs to refresh.

To disable this check define the cfengine_internal_disable_cf_promises_validated class.

It not recommended to disable this check as it both removes a safety mechanism that checks for policy to be valid before allowing clients to download updates, and the increased load on the hub will affect scalability.

If you want to periodically perform a full scan consider adding custom policy to simply remove $(sys.inputdir)/cf_promises_validated. This will cause the file to be repaired during the next update run triggering a full scan.

Automatically remove files not present upstream (SYNC masterfiles)

If the class cfengine_internal_purge_policies is defined the update behavior to change from only copying changed files down to performing a synchronization by purging files on the client that do not exist on the server.

This augments file will enable this behavior for all clients.

{
  "classes": {
    "cfengine_internal_purge_policies": [ "any" ]
  }
}

Automatically deploy masterfiles from Version Control

On a CFEngine Enterprise Hub during the update policy if the class cfengine_internal_masterfiles_update is defined masterfiles will be automatically deployed from an upstream version control repository using the settings defined via Mission Portal or directly in /opt/cfengine/dc-scripts.

Note: Any policy in the distribution location (/var/cfengine/masterfiles) will be deleted the first time this tooling runs. Be wary of local modifications before enabling.

Policy Permissions

By default the policy enforces permissions of 0600 meaning that inputs are only readable by their owner. If you are distributing scripts with your masterfiles, be sure there is a policy to ensure they are executable when you expect them to be.

Agent binary upgrades

Remote agents can upgrade their own binaries using the built in binary upgrade policy. Packages must be placed in /var/cfengine/master_software_updates in the appropriate platform directory. Clients will automatically download and install packages when the trigger_upgrade class is defined during a run of update.cf.

Note: This policy is specific to CFEngine Enterprise.

This augments file would define the trigger_upgrade class if the testhost5 class is defined.

{
  "classes": {
    "trigger_upgrade": [ "testhost5" ]
  }

}

Files considered for copy during policy updates

The default update policy only copies files that match regular expressions listed in def.input_name_patterns.

This augments file ensures that only files ending in .cf, .dat, .mustache, .json, .yaml and the file cf_promises_release_id will be considered by the default update policy.

{
  "vars:" {
    "input_name_patterns": [ ".*\\.cf", ".*\\.dat",
                             ".*\\.mustache",
                             "cf_promises_release_id",
                             ".*\\.json", ".*\\.yaml" ]
  }
}

Note: This filter does not apply to bootstrap operations. During bootstrap the embedded failsafe policy is used and it decides which files should be copied.

Enable or disable CFEngine components

persistent_disable_*DAEMON*

Description: Disable a CFEngine Enterprise daemon component persistently.

DAEMON can be one of cf_execd, cf_monitord or cf_serverd.

This will stop the AGENT from starting automatically.

This augments file will ensure that cf-monitord is disabled on hosts that have server1 or the redhat class defined.

{
  "classes": {
    "persistent_disable_cf_monitord": [ "server1", "redhat" ]
  }
}

clear_persistent_disable_*DAEMON*

Description: Re-enable a previously disabled CFEngine Enterprise daemon component.

DAEMON can be one of cf_execd, cf_monitord or cf_serverd.

This augments file will ensure that cf-monitord is not disabled on redhat hosts.

{
  "classes": {
    "clear_persistent_disable_cf_monitord": [ "redhat" ]
  }
}

Main Policy (promises.cf)

The following settings are defined in controls/def.cf can be set from an augments file.

mailto

The address that cf-execd should email agent output to.

mailfrom

The address that output mailed from cf-execd should come from.

smtpserver

The SMTP server that cf-execd should use to send emails.

acl

This is a list of of network ranges that the hub should allow download of policy files from.

trustkeysfrom

The list of network ranges that cf-serverd should trust keys from. This is should only be open on policy servers while new hosts are expected to be bootstrapped. It should be empty after your hosts have been bootstrapped to avoid unwanted hosts from being able to bootstrap.

services_autorun

When the services_autorun class is defined bundles tagged with autorun are actuated in lexical order.

bundle agent example
{
  meta:
    "tags" slist => { "autorun" };

  reports:
    "I will report when 'services_autorun' is defined."
}

Note: .cf files located in services/autorun/ are automatically included in inputs even when the services_autorun class is not defined. Bundles tagged with autorun are not required to be placed in services/autorun/ in order to be automatically actuated.

postgresql_full_maintenance

On CFEngine Enterprise policy hubs this class is defined by default on Sundays at 2am. To adjust when postgres maintenance operations run edit controls/def.cf directly.

postgresql_vacuum

On CFEngine Enterprise policy hubs this class is defined by default at 2am when postgresql_maintenance_supported is defined except for Sundays.

To adjust when postgres maintenance operations run edit controls/def.cf directly.

enable_cfengine_enterprise_hub_ha

Set this class when you want to enable the CFEngine Enterprise HA policies.

This class can be defined by an augments file. For example:

{
  "classes" {
    "enable_cfengine_enterprise_hub_ha": [ "hub001" ]
  }
}

enable_cfe_internal_cleanup_agent_reports

This class enables policy that cleans up report diffs when they exceed def.maxclient_history_size. By default is is off unless a CFEngine Enterprise agent is detected.

Main Policy (promises.cf)

Append to the main bundlesequence

You can specify bundles which should be run at the end of the default bundlesequence by defining control_common_bundlesequence_end in the vars of an augments file.

For example:

{
  "vars":{
    "control_common_bundlesequence_end": [ "mybundle1", "mybundle2" ]
  }

  "inputs": [ "services/mybundles.cf" ]
}

Notes:

  • The order in which bundles are actuates is not guaranteed.
  • The agent will error if a named bundle is not part of inputs.

History: Added in 3.10.0

Configure default repository for file backups

By default the agent creates a backup of a file before it is edited in the same directory as the edited file. Defining the mpf_control_agent_default_repository class will cause these backups to be placed in $(sys.workdir)/backups. Customize the backup directory by setting def.control_agent_default_backup.

For example:

{
  "classes": {
    "mpf_control_agent_default_repository": [ "any" ]
  },

  "vars": {
    "control_agent_default_repository": "/var/cfengine/edit_backups"
  }
}

History: Added in 3.10.1