Components and Common Control

Table of Contents

While promises to configure your system are entirely user-defined, the details of the operational behavior of the CFEngine software is of course hard-coded. You can still configure the details of this behavior using the control promise bodies. Control behavior is defined in bodies because the actual promises are fixed and you only change their details within sensible limits.

See the introduction for a high-level overview of the CFEngine components, and each component's reference documentation for the details about the specific control bodies.

Common Control

The common control body refers to those promises that are hard-coded into all the components of CFEngine, and therefore affect the behavior of all the components.

     body common control

     {
     inputs  => {
                "update.cf",
                "library.cf"
                };

     bundlesequence  => {
                        update("policy_host.domain.tld"),
                        "main",
                        "cfengine2"
                        };

     goal_categories => { "goals", "targets", "milestones" };
     goal_patterns   => { "goal_.*", "target.*" };

     output_prefix => "cfengine>";
     version => "1.2.3";
     }

bundlesequence

Description: The bundlesequence contains promise bundles to verify, in a specific order.

The bundlesequence determines which of the compiled bundles will be executed by cf-agent and in what order they will be executed. The list refers to the names of bundles (which might be parameterized, function-like objects).

The default value for bundlesequence is { "main" }.

A bundlesequence may also be specified using the -b or --bundlesequence command line option.

Type: slist

Allowed input range: .*

Example:

    body common control

    {
    bundlesequence  => {
                       update("policy_host.domain.tld"),
                       "main",
                       "cfengine2"
                       };
    }

Note: Only common and agent bundles are allowed to be listed in the bundlesequence.

The order in which you execute bundles can affect the outcome of your promises. In general you should always define variables before you use them.

The bundlesequence is like a genetic makeup of a machine. The bundles act like characteristics of the systems. If you want different systems to have different bundlesequences, distinguish them with classes

    webservers::

      bundlesequence => { "main", "web" };

    others::

      bundlesequence => { "main", "otherstuff" };

If you want to add a basic common sequence to all sequences, then use global variable lists to do this:

    body common control
    {
    webservers::

      bundlesequence => { @(g.bs), "web" };

    others::

      bundlesequence => { @(g.bs), "otherstuff" };

    }

    bundle common g
    {
    vars:

      "bs" slist => { "main", "basic_stuff" };
    }

History: The default to { "main" } was introduced in version 3.7.0, so if you expect your policies to be run by older version, you'll need an explicit bundlesequence.

bwlimit

Description: Coarse control of bandwidth any cf-serverd or cf-agent process will send out. In Bytes/sec.

Bandwidth limit is meant to set an upper bound of traffic coming out of CFEngine agents or servers, as a countermeasure against network abuse from them. The limit is applied to all interfaces (in total), a single process at a time. It can prevent network being flooded by CFEngine traffic when large files or many agents hit a single cf-serverd.

For more fine-grained control, please use operating system (eg. iptables) facilities.

Note: Bandwidth limiting is currently not supported on Windows.

Type: [float][float]

Default value: none (no limit)

Example:

    body common control

    {
      bwlimit => "10M";
    }

In this example, bwlimit is set to 10MBytes/sec = 80Mbit/s meaning that CFEngine would only consume up to ~80% of any 100Mbit ethernet interface.

cache_system_functions

Description: Controls the caching of the results of system functions, e.g. execresult() and returnszero() for shell execution and ldapvalue() and friends for LDAP queries. Without this setting, CFEngine's evaluation model will evaluate functions multiple times, which is a performance concern. See Functions.

Although you can override this to false, in practice you should almost never need to do so. The effect of having it true (the default) is that the expensive functions will be run just once and then their result will be cached.

Note that caching is per-process so results will not be cached between runs of e.g. cf-agent and cf-promises.

Type: boolean

Default value: true

Example:

    cache_system_functions => "true";

History: Was introduced in version 3.6.0.

domain

Description: The domain string specifies the domain name for this host.

There is no standard, universal or reliable way of determining the DNS domain name of a host, so it can be set explicitly to simplify discovery and name-lookup.

Type: string

Allowed input range: .*

Example:

    body common control
    {
    domain => "example.org";
    }

goal_patterns

Description: Contains regular expressions that match promisees/topics considered to be organizational goals

It is used as identifier to mark business and organizational goals in CFEngine Enterprise. CFEngine uses this to match promisees that represent business goals in promises.

Type: slist

Allowed input range: (arbitrary string)

Example:

    body common control
    {
    goal_patterns => { "goal_.*", "target.*" };
    }

History: Was introduced in version 3.1.5, Nova 2.1.0 (2011)

ignore_missing_bundles

Description: Determines whether to ignore missing bundles.

If ignore_missing_bundles is set to true, if any bundles in the bundle sequence do not exist, ignore and continue.

Type: boolean

Default value: false

Example:

    ignore_missing_bundles => "true";

Notes:

This authorizes the bundlesequence to contain possibly "nonexistent" pluggable modules. It defaults to false, whereupon undefined bundles cause a fatal error in parsing, and a transition to failsafe mode.

ignore_missing_inputs

Description: If any input files do not exist, ignore and continue

The inputs lists determines which files are parsed by CFEngine. Normally stringent security checks are made on input files to prevent abuse of the system by unauthorized users.

Sometimes however, it is appropriate to consider the automatic plug-in of modules that might or might not exist. This option permits CFEngine to list possible files that might not exist and continue 'best effort' with those that do exist. The default of all Booleans is false, so the normal behavior is to signal an error if an input is not found.

Type: boolean

Default value: false

Example:

    ignore_missing_inputs => "true";

inputs

Description: The inputs slist contains additional filenames to parse for promises.

The filenames specified are all assumed to be in the same directory as the file which references them (this is usually $(sys.workdir)/inputs, but may be overridden by the -f or --file command line option.

Type: slist

Allowed input range: .*

Example:

    body common control
    {
    inputs  => {
               "update.cf",
               "library.cf"
               };
    }

See also: inputs in body file control

Notes:

If no filenames are specified, no other filenames will be included in the compilation process.

Library contents are checked for duplication by path and by hash. For example, if you put library.cf twice in your inputs, the duplicate library.cf is noticed because the same path is included twice. A verbose-level message is emitted but otherwise there is no error.

In addition, if you include a file once with path /x/y/z.cf and again with path /x/./y/z.cf, the duplicate file will be rejected regardless of any path tricks or symbolic links. The contents are hashed, so the same file can't be included twice.

lastseenexpireafter

Description: The value of lastseenexpireafter is the number of minutes after which last-seen entries are purged. It is an enterprise-only feature.

Type: int

Allowed input range: 0,99999999999

Default value: One week

Note: This value affects the hostsseen() function and license counting by cf-hub in the Enterprise edition.

Example:

    body common control
    {
    lastseenexpireafter => "72";
    }

See Also: hostsseen(), cf-hub

output_prefix

Description: The string prefix for standard output

Type: string

Allowed input range: (arbitrary string)

Example:

    body common control
    {
    output_prefix => "my_cf3";
    }

Notes:

On native Windows versions of CFEngine (Enterprise), this string is also prefixed messages in the event log.

package_inventory

Description: List of package module bodies to query for package lists.

Defines the list of package module bodies which will be queries for package lists, for use in packagematching(), packageupdatesmatching() and in Enterprise inventory reporting.

Type: slist

Allowed input range: (body names)

Example:

body common control
{
    package_inventory => { "apt_get" };
}

package_module

Description: The default package module body to use.

Defines the default package module body to use for package promises, if none is specified in the promise.

Type: string

Allowed input range: (body name)

Example:

body common control
{
    package_module => "apt_get";
}

protocol_version

Description: Defines the protocol to use for all outgoing connections.

Type: (menu option)

Allowed input range:

  • 0
  • undefined
  • 1
  • classic
  • 2
  • latest

Default value: 2

  • 0 -
  • undefined -
  • 1 - Classic protocol
  • classic - Alias to protocol 1
  • 2 - TLS
  • latest - Alias to protocol 2

Note: protocol_version can be specified at the individual promise level using the body copy_from protocol_version attribute.

See also: body copy_from protocol_version, allowlegacyconnects, allowtlsversion, allowciphers, tls_min_version, tls_ciphers, encrypt, logencryptedtransfers, ifencrypted

History: Introduced in CFEngine 3.6.0

require_comments

Description: The require_comments menu option policy warns about promises that do not have comment documentation.

When true, cf-promises will report loudly on promises that do not have comments. Variables promises are exempted from this rule, since they may be considered self-documenting. This may be used as a policy Quality Assurance measure, to remind policy makers to properly document their promises.

Type: boolean

Default value: false

Example:

    body common control

    {
    common::

    require_comments => "true";
    }

site_classes

Description: A site_classes contains classes that will represent geographical site locations for hosts. These should be defined elsewhere in the configuration in a classes promise.

This list is used to match against topics when connecting inferences about host locations in the knowledge map. Normally any CFEngine classes promise whose name is defined as a thing or topic under class locations:: will be assumed to be a location defining classifier. This list will add alternative class contexts for interpreting location.

Type: slist

Allowed input range: [a-zA-Z0-9_!&@@$|.()\[\]{}:]+

Each string is expected to be a class.

Example:

    body common control
    {
    site_classes => { "datacenters","datacentres"  }; # locations is by default
    }

History: Was introduced in version 3.2.0, Nova 2.1.0 (2011)

syslog_host

Description: The syslog_host contains the name or address of a host to which syslog messages should be sent directly by UDP.

This is the hostname or IP address of a local syslog service to which all CFEngine's components may promise to send data.

Type: string

Allowed input range: [a-zA-Z0-9_$(){}.:-]+

Default value: localhost

Example:

    body common control
    {
    syslog_host => "syslog.example.org";
    syslog_port => "514";
    }

syslog_port

Description: The value of syslog_port represents the port number of a UDP syslog service.

It is the UDP port of a local syslog service to which all CFEngine's components may promise to send data.

Type: int

Allowed input range: 0,99999999999

Default value: 514

Example:

    body common control
    {
    syslog_host => "syslog.example.org";
    syslog_port => "514";
    }

tls_ciphers

Description: List of ciphers allowed when making outgoing connections.

For a list of possible ciphers, see man page for "openssl ciphers".

Type: string

Allowed input range: (arbitrary string)

Default value: undefined

Example:

body common control
{
    # Use one of these ciphers when making outbound connections
    tls_ciphers => "AES128-SHA";
}

See also: protocol_version, allowciphers, tls_min_version, allowtlsversion, encrypt, logencryptedtransfers, ifencrypted

History: Introduced in CFEngine 3.7.0

tls_min_version

Description: Minimum tls version to allow for outgoing connections.

Type: string

Allowed input range: (arbitrary string)

Default value: 1.0

body common control
{
    # Allow only TLSv1.1 or higher for outgoing connections
    tls_min_version => "1.1";
}

See also: protocol_version, allowciphers, tls_ciphers, allowtlsversion, encrypt, ifencrypted, logencryptedtransfers

History: Introduced in CFEngine 3.7.0

version

Description: The version string contains the scalar version of the configuration.

It is is used in error messages and reports.

Type: string

Allowed input range: (arbitrary string)

This string should not contain the colon ':' character, as this has a special meaning in the context of knowledge management. This restriction might be lifted later.

Example:

    body common control
    {
    version => "1.2.3";
    }

Deprecated attributes in body common control

The following attributes were functional in previous versions of CFEngine, but today they are deprecated, either because their functionality is being handled trasparently or because it doesn't apply to current CFEngine version.

  • fips_mode
  • host_licenses_paid