cf-agent

cf-agent evaluates policy code and makes changes to the system. Policy bundles are evaluated in the order of the provided bundlesequence (this is normally specified in the common control body). For each bundle, cf-agent groups promise statements according to their type. Promise types are then evaluated in a preset order to ensure fast system convergence to policy.

cf-agent keeps the promises made in common and agent bundles, and is affected by common and agent control bodies.

Command reference

--bootstrap, -B
    Bootstrap CFEngine to the given policy server IP, hostname or :avahi (automatic detection)

--bundlesequence, -b
    Set or override bundlesequence from command line

--debug, -d
    Enable debugging output

--define, -D
    Define a list of comma separated classes to be defined at the start of execution

--self-diagnostics, -x
    Run checks to diagnose a CFEngine agent installation

--dry-run, -n
    All talk and no action mode - make no changes, only inform of promises not kept

--file, -f
    Specify an alternative input file than the default

--help, -h
    Print the help message

--inform, -I
    Print basic information about changes made to the system, i.e. promises repaired

--negate, -N
    Define a list of comma separated classes to be undefined at the start of execution

--no-lock, -K
    Ignore locking constraints during execution (ifelapsed/expireafter) if "too soon" to run

--verbose, -v
    Output verbose information about the behaviour of the agent

--version, -V
    Output the version of the software

--legacy-output, -l
    Use legacy output format

--color, -C
    Enable colorized output. Possible values: 'always', 'auto', 'never'. Default is 'never'

Automatic Bootstrapping

Automatic bootstrapping allows the user to connect a CFEngine Host to a Policy Server without specifying the IP address manually. It uses the Avahi service discovery implementation of zeroconf to locate the Policy Server, obtain its IP address, and then connect to it. To use automatic bootstrap, install the following Avahi libraries:

• libavahi-client
• libavahi-common

To make the CFEngine Server discoverable, it needs to register itself as an Avahi service. Run the following command:

    $ /var/cfengine/bin/cf-serverd -A

This generates the configuration file for Avahi in /etc/avahi/services and restarts the Avahi daemon in order to register the new service.

From this point on, the Policy Server will be discovered with the Avahi service. To verify that the server is visible, run the following command (requires avahi-utils):

    $ avahi-browse -atr | grep cfenginehub

The sample output looks like this:

    eth0 IPv4 CFEngine Community 3.5.0 Policy Server on policy_hub_debian7
    _cfenginehub._tcp local

Once the Policy Server is configured with the Avahi service, you can auto-bootstrap Hosts to it.

    $ /var/cfengine/bin/cf-agent -B :avahi

The Hosts require Avahi libraries to be installed in order to use this functionality. By default cf-agent looks for libraries in standard install locations. Install locations vary from system to system. If Avahi is installed in a non-standard location (i.e. compiled from source), set the AVAHI_PATH environmental variable to specify the path.

   $ AVAHI_PATH=/lib/libavahi-client.so.3 /var/cfengine/bin/cf-agent -B

If more than one server is found, or if the server has more than one IP address, the list of all available servers is printed and the user is asked to manually specify the IP address of the correct server by running the standard bootstrap command of cf-agent:

   $ /var/cfengine/bin/cf-agent --bootstrap <IP address>

If only one Policy Server is found in the network, cf-agent performs the bootstrap without further manual user intervention.

Note: Automatic bootstrapping support is ONLY for Linux, and it is limited only to one subnet.

Control Promises

Settings describing the details of the fixed behavioral promises made by cf-agent.

    body agent control
    {
    123_456_789::

      domain => "mydomain.com";

    123_456_789_111::

      auditing => "true";

    any::

      fullencryption => "true";

    }

abortclasses

Description: The abortclasses slist contains classes which if defined lead to termination of cf-agent.

Regular expressions are used for classes that cf-agent will watch out for. If any matching class becomes defined, it will cause the current execution of cf-agent to be aborted. This may be used for validation, for example. To handle class expressions, simply create an alias for the expression with a single name.

Type: slist

Allowed input range: .*

Example:

     body agent control

      {
      abortclasses => { "danger.*", "should_not_continue" };
      }

abortbundleclasses

Description: The abortbundleclasses slist contains classes which if defined lead to termination of current bundle.

Regular expressions are used for classes, or class expressions that cf-agent will watch out for. If any of these classes becomes defined, it will cause the current bundle to be aborted. This may be used for validation, for example.

Type: slist

Allowed input range: .*

Example: This example shows how to use the feature to validate input to a method bundle.

    body common control

    {
    bundlesequence  => { "testbundle"  };
    version => "1.2.3";
    }

    #################################

    body agent control

    {
    abortbundleclasses => { "invalid.*" };
    }

    #################################

    bundle agent testbundle
    {
    vars:

     "userlist" slist => { "xyz", "mark", "jeang", "jonhenrik", "thomas", "eben" };

    methods:

     "any" usebundle => subtest("$(userlist)");

    }

    #################################

    bundle agent subtest(user)

    {
    classes:

      "invalid" not => regcmp("[a-z]{4}","$(user)");

    reports:

     !invalid::

      "User name $(user) is valid at exactly 4 letters";

     # abortbundleclasses will prevent this from being evaluated
     invalid::

      "User name $(user) is invalid";
    }

addclasses

Description: The addclasses slist contains classes to be defined always in the current context.

This adds global, literal classes. The only predicates available during the control section are hard-classes.

Type: slist

Allowed input range: .*

Example:

    any::

      addclasses => { "My_Organization" }

    solaris::

      addclasses => { "some_solaris_alive", "running_on_sunshine" };

Notes:

Another place to make global aliases for system hardclasses. Classes here are added unequivocally to the system. If classes are used to predicate definition, then they must be defined in terms of global hard classes.

agentaccess

Description: A agentaccess slist contains user names that are allowed to execute cf-agent.

This represents a list of user names that will be allowed to attempt execution of the current configuration. This is mainly a sanity check rather than a security measure.

Type: slist

Allowed input range: .*

Example:

     agentaccess => { "mark", "root", "sudo" };

agentfacility

Type: (menu option)

Allowed input range:

   LOG_USER
   LOG_DAEMON
   LOG_LOCAL0
   LOG_LOCAL1
   LOG_LOCAL2
   LOG_LOCAL3
   LOG_LOCAL4
   LOG_LOCAL5
   LOG_LOCAL6
   LOG_LOCAL7

Default value: LOG_USER

Description: The agentfacility mentu option policy sets the agent's syslog facility level.

Example:

    agentfacility => "LOG_USER";

Notes:

This is ignored on Windows, as CFEngine Enterprise creates event logs.

See Also: Manual pages for syslog.

allclassesreport

Description: The allclassesreport menu option policy determines whether to generate the allclasses.txt report.

If set to true, the state/allclasses.txt file will be written to disk during agent execution.

Type: boolean

Default value: false

Example:

    body agent control
    {
    allclassesreport => "true";
    }

Notes:

This functionality is retained only for CFEngine 2 compatibility. As of CFEngine 3.5, the classesmatching() function provides a more convenient way to retrieve a list of set classes at execution time.

History: Was introduced in 3.2.4, Enterprise 2.1.4 (2011)

alwaysvalidate

Description: The alwaysvalidate menu option policy is a true/false flag to determine whether configurations will always be checked before executing, or only after updates.

Type: boolean

Example:

    body agent control
    {
    Min00_05::

      # revalidate once per hour, regardless of change in configuration

      alwaysvalidate => "true";
    }

Notes:

The agents cf-agent and cfserverd can run cf-promises to validate inputs before attempting to execute a configuration. As of version 3.1.2 core, this only happens if the configuration file has changed to save CPU cycles. When this attribute is set, cf-agent will force a revalidation of the input.

History: Was introduced in version 3.1.2,Enterprise 2.0.1 (2010)

auditing

Deprecated: This menu option policy is deprecated, does nothing and is kept for backward compatibility.

Type: boolean

Default value: false

Example:

    body agent control
    {
    auditing  => "true";
    }

binarypaddingchar

Description: The binarypaddingchar contains the character used to pad unequal replacements in binary editing.

When editing binary files, it can be dangerous to replace a text string with one that is longer or shorter as byte references and jumps would be destroyed. CFEngine will therefore not allow replacements that are larger in size than the original, but shorter strings can be padded out to the same length.

Type: string

Allowed input range: (arbitrary string)

Default value: space (ASC=32)

Example:

    body agent control
    {
    binarypaddingchar => "#";
    }

Default value: empty (i.e., no padding)

bindtointerface

Description: The bindtointerface string describes the interface to be used for outgoing connections.

On multi-homed hosts, the server and client can bind to a specific interface for server traffic. The IP address of the interface must be given as the argument, not the device name.

Type: string

Allowed input range: .*

Example:

    bindtointerface => "192.168.1.1";

hashupdates

Description: The hashupdates determines whether stored hashes are updated when change is detected in source.

If 'true' the stored reference value is updated as soon as a warning message has been given. As most changes are benign (package updates etc) this is a common setting.

Type: boolean

Default value: false

Example:

    body agent control
    {
    hashupdates => "true";
    }

childlibpath

Description: The childlibpath string contains the LD_LIBRARY_PATH for child processes.

This string may be used to set the internal LD_LIBRARY_PATH environment of the agent.

Type: string

Allowed input range: .*

Example:

    body agent control
    {
    childlibpath => "/usr/local/lib:/usr/local/gnu/lib";
    }

checksum_alert_time

Description: The value of checksum_alert_time represents the persistence time for the checksum_alert class.

When checksum changes trigger an alert, this is registered as a persistent class. This value determines the longevity of that class.

Type: int

Allowed input range: 0,60

Default value: 10 mins

Example:

    body agent control
    {
    checksum_alert_time => "30";
    }

defaultcopytype

Description: The defaultcopytype menu option policy sets the global default policy for comparing source and image in copy transactions.

Type: (menu option)

Allowed input range:

   mtime
   atime
   ctime
   digest
   hash
   binary

Example:

    body agent control
    {
    #...
    defaultcopytype => "digest";
    }

default_repository

Description: The default_repository string contains the path to the default file repository.

If defined the default repository is the location where versions of files altered by CFEngine are stored. This should be understood in relation to the policy for 'backup' in copying, editing etc. If the backups are time-stamped, this becomes effective a version control repository.

Type: string

Allowed input range: "?(/.*)

Default value: in situ

Example:

    body agent control
    {
    default_repository => "/var/cfengine/repository";
    }

Notes: When a repository is specified, the files are stored using the canonified directory name of the original file, concatenated with the name of the file. So, for example, /usr/local/etc/postfix.conf would ordinarily be stored in an alternative repository as _usr_local_etc_postfix.conf.cfsaved.

default_timeout

Description: The value of default_timeout represents the maximum time a network connection should attempt to connect.

The time is in seconds. It is not a guaranteed number, since it depends on system behavior.

Type: int

Allowed input range: 0,99999999999

Default value: 10 seconds

Example:

    body agent control
    {
    default_timeout => "10";
    }

Notes: Under Linux, the kernel version plays a role, since not all system calls seem to respect the signals.

dryrun

Description: The dryrun menu option, if set, makes no changes to the system, and will only report what it needs to do.

Type: boolean

Default value: false

Example:

    body agent control
    {
    dryrun => "true";
    }

editbinaryfilesize

Description: The value of editbinaryfilesize represents the limit on maximum binary file size to be edited.

This is a global setting for the file-editing safety-net for binary files, and may be overridden on a per-promise basis with max_file_size.

Type: int

Allowed input range: 0,99999999999

Default value: 100k

Example:

    body agent control
    {
    edibinaryfilesize => "10M";
    }

Notes: When setting limits, the limit on editing binary files should generally be set higher than for text files.

editfilesize

Description: The value of editfilesize is the limit on maximum text file size to be edited.

This is a global setting for the file-editing safety-net, and may be overridden on a per-promise basis with max_file_size.

Type: int

Allowed input range: 0,99999999999

Default value: 100000

Example:

    body agent control
    {
    editfilesize => "120k";
    }

environment

Description: The environment slist contains environment variables to be inherited by children.

This may be used to set the runtime environment of the agent process. The values of environment variables are inherited by child commands.

Type: slist

Allowed input range: [A-Za-z0-9_]+=.*

Example:

    body common control
    {
    bundlesequence => { "one" };
    }

    body agent control
    {
    environment => { "A=123", "B=456", "PGK_PATH=/tmp"};
    }

    bundle agent one
    {
    commands:

      "/usr/bin/env";
    }

Some interactive programs insist on values being set, for example:

    # Required by apt-cache, debian

    environment => { "LANG=C"};

expireafter

Description: The value of expireafter is a global default for time before on-going promise repairs are interrupted.

This represents the locking time after which CFEngine will attempt to kill and restart its attempt to keep a promise.

Type: int

Allowed input range: 0,99999999999

Default value: 1 min

Example:

    body action example
    {
    ifelapsed   => "120";   # 2 hours
    expireafter => "240";   # 4 hours
    }

files_single_copy

Description: The files_single_copy slist contains filenames to be watched for multiple-source conflicts.

This list of regular expressions will ensure that files matching the patterns of the list are never copied from more than one source during a single run of cf-agent. This may be considered a protection against accidential overlap of copies from diverse remote sources, or as a first-come-first-served disambiguation tool for lazy-evaluation of overlapping file-copy promises.

Type: slist

Allowed input range: (arbitrary string)

Example:

    body agent control
    {
    files_single_copy => { "/etc/.*", "/special/file" };
    }

files_auto_define

Description: The files_auto_define slist contains filenames to define classes if copied.

Classes are automatically defined by the files that are copied. The file is named according to the prefixed 'canonization' of the file name. Canonization means that non-identifier characters are converted into underscores. Thus /etc/passwd would canonize to _etc_passwd. The prefix auto_ is added to clarify the origin of the class. Thus in the example the copying of /etc/passwd would lead to the class auto__etc_passwd being defined automatically.

Type: slist

Allowed input range: (arbitrary string)

Example:

    body agent control
    {
    files_auto_define => { "/etc/syslog\.c.*", "/etc/passwd" };
    }

hostnamekeys

Deprecated: Host identification is now handled transparently.

Description: The hostnamekeys menu option policy determines whether to label ppkeys by hostname not IP address.

This represents a client side choice to base key associations on host names rather than IP address. This is useful for hosts with dynamic addresses.

Type: boolean

Default value: false

Example:

    body server control
    {
    hostnamekeys => "true";
    }

ifelapsed

Description: The value of ifelapsed is a global default representing the time that must elapse before a promise will be rechecked.

This overrides the global settings. Promises which take a long time to verify should usually be protected with a long value for this parameter. This serves as a resource 'spam' protection. A CFEngine check could easily run every 5 minutes provided resource intensive operations are not performed on every run. Using time classes like Hr12 etc., is one part of this strategy; using ifelapsed is another which is not tied to a specific time.

Type: int

Allowed input range: 0,99999999999

Default value: 1

Example:

    #local

    body action example
    {
    ifelapsed   => "120";   # 2 hours
    expireafter => "240";   # 4 hours
    }

    # global

    body agent control
    {
    ifelapsed   => "180";   # 3 hours
    }

inform

Description: The inform menu option policy sets the default output level 'permanently' within the class context indicated.

It is equivalent to (and when present, overrides) the command line option '-I'.

Type: boolean

Default value: false

Example:

    body agent control
    {
    inform => "true";
    }

intermittency

Deprecated: This attribute does nothing and is kept for backward
compatibility.

Type: boolean

Default value: false

max_children

Description: The value of max_children represents the maximum number of background tasks that should be allowed concurrently.

For the run-agent this is the maximum number of forked background processes allowed when parallelizing connections to servers. For the agent it represents the number of background jobs allowed concurrently. Background jobs often lead to contention of the disk resources slowing down tasks considerably; there is thus a law of diminishing returns.

Type: int

Allowed input range: 0,99999999999

Default value: 1 concurrent agent promise

Example:

    body agent control
    {
    max_children => "10";
    }

maxconnections

Description: The value of maxconnections represents the maximum number of outgoing connections to cf-serverd.

Type: int

Allowed input range: 0,99999999999

Default value: 30 remote queries

Example:

    # client side 

    body agent control
    {
    maxconnections => "1000";
    }

Notes:

Watch out for kernel limitations for maximum numbers of open file descriptors which can limit this.

mountfilesystems

Description: The mountfilesystems menu option policy determines whether to mount any filesystems promised.

It issues the generic command to mount file systems defined in the file system table.

Type: boolean

Default value: false

Example:

    body agent control
    {
    mountfilesystems => "true";
    }

nonalphanumfiles

Description: The nonalphanumfiles menu option policy determines whether to warn about filenames with no alphanumeric content.

This test is applied in all recursive/depth searches.

Type: boolean

Default value: false

Example:

    body agent control
    {
    nonalphanumfiles => "true";
    }

repchar

Description: The repchar string represents a character used to canonize pathnames in the file repository.

Type: string

Allowed input range: .

Default value: _

Example:

    body agent control
    {
    repchar => "_";
    }

Notes:

refresh_processes

Description: The refresh_processes slist contains bundles to reload the process table before verifying the bundles named in this list (lazy evaluation).

If this list of regular expressions is non-null and an existing bundle is mentioned or matched in this list, CFEngine will reload the process table at the start of the named bundle, each time is is scheduled. If the list is null, the process list will be reloaded at the start of every scheduled bundle.

Type: slist

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

Example:

    body agent control
    {
    refresh_processes => { "mybundle" };
    #refresh_processes => { "none" };
    }

This examples uses a non-empty list with the name 'none'. This is not a reserved word, but as long as there are no bundles with the name 'none' this has the effect of never reloading the process table. This keeps improves the efficiency of the agent.

History: Was introduced in version 3.1.3, Enterprise 2.0.2 (2010)

secureinput

Description: The secureinput menu option policy checks whether input files are writable by unauthorized users.

If this is set, the agent will not accept an input file that is not owned by a privileged user.

Type: boolean

Default value: false

Example:

    body agent control
    {
    secureinput => "true";
    }

sensiblecount

Description: The value of sensiblecount represents the minimum number of files a mounted filesystem is expected to have.

Type: int

Allowed input range: 0,99999999999

Default value: 2 files

Example:

    body agent control 
    {
    sensiblecount => "20";
    }

sensiblesize

Description: The value of sensiblesize represents the minimum number of bytes a mounted filesystem is expected to have.

Type: int

Allowed input range: 0,99999999999

Default value: 1000 bytes

Example:

    body agent control
    {
    sensiblesize => "20K";
    }

skipidentify

Description: The skipidentify menu option policy determines whether to send an IP/name during server connection because address resolution is broken.

Hosts that are not registered in DNS cannot supply reasonable credentials for a secondary confirmation of their identity to a CFEngine server. This causes the agent to ignore its missing DNS credentials.

Type: boolean

Default value: false

Example:

    body agent control
    {
    skipidentify => "true";
    }

suspiciousnames

Description: The suspiciousnames slist contains names to warn about if found during any file search.

If CFEngine sees these names during recursive (depth) file searches it will warn about them.

Type: slist

Allowed input range: (arbitrary string)

Example:

    body agent control
    {
    suspiciousnames => { ".mo", "lrk3", "rootkit" };
    }

syslog

Description: The syslog menu option policy determines wether to switch on output to syslog at the inform level.

Type: boolean

Default value: false

Example:

    body agent control
    {
    syslog => "true";
    }

track_value

Description: The track_value menu option policy determines whether to switch on tracking of promise valuation.

If true, CFEngine generates a log in WORKDIR/state/cf_value.log of the estimated 'business value' of the system automation as a running log, value_kept, etc. The format of the file is date, sum value kept, sum value repaired, sum value notkept.

Type: boolean

Default value: false

Example:

    body agent control
    {
    track_value => "true";
    }

timezone

Description: The timezone slist contains allowed timezones this machine must comply with.

Type: slist

Allowed input range: (arbitrary string)

Example:

    body agent control
    {
    timezone => { "MET", "CET", "GMT+1" };
    }

verbose

Description: The verbose menu option policy determines whether to switch on verbose standard output.

It is equivalent to (and when present, overrides) the command line option '-v'. Sets the default output level 'permanently' for this promise.

Type: boolean

Default value: false

Example:

    body agent control
    {
    verbose => "true";
    }