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What is new in CFEngine 3.6

What is new

• User promises• TLS protocol• Math expressions• Dynamic inputs• New language functions• Tags• Data containers• File templating

User promises

User promises

• A new promise type• Manage local users on hosts• Make promises about user

characteristics• UID

• Group membership

• Home directory

• Password

• Shell

• Description

User promises - Example

bundle agent my_bundle {

users:

“joe”

policy => “present”,

group_primary => “users”,

groups_secondary => { “printers”,

“db_users” },

home_dir => “/nfs/home/joe”,

home_bundle => setup_home_dir(“joe”);

}

TLS protocol

TLS protocol

• Industry standard security protocol• All traffic is fully encrypted• Transparent to the user• Old protocol

• Deprecated, but still supported

• Can be turned off after upgrade is complete

Math expressions

Math expressions

• New math evaluation function: eval()• Works on strings• String contains expression to evaluate

• Example: eval(“ceil($(sys.cpus) / 4)”)

• Previously required shell script

Math expressions

• Accepts common math operators: +, -, *, /

• Some less common ones too: ^, **, %

• Many common math functions• ceil, floor, log10, log2, log, sqrt, sin, cos, tan, asin, acos, atan, abs, step

• Mathematical constants• e, log2e, log10e, ln2, ln10, pi, pi_2, pi_4, 1_pi, 2_pi, 2_srqtpi, sqrt2, sqrt1_2

• SI-units: K, M, G, T, P

Dynamic inputs

Dynamic inputs

• 3.5:• Input files can only be defined in promises.cf

• Inconvenient; all file additions require editing promises.cf

• 3.6:• file control bodies can contain input files

• Body can be specified once per file• body file control {

inputs => “input_file.cf”;

}

Dynamic inputs - Example

• promises.cfbody common control {

inputs => { “input_file.cf” };

}

• input_file.cfbody file control {

inputs => { “nested_input_file.cf” };

}

New language functions

New language functions

• findfiles(glob1, glob2, ...)• Returns a list of files that match glob pattern

• makerule(target, sources)• Determines whether target needs to be rebuilt from sources

• Inspired by the Unix make program

• packagesmatching(...)• Returns list of installed packages

• List can be filtered by name, version and architecture

New language functions

• canonifyuniquely(test)• Convert a string into a legal class name

• Unlike canonify, name is guaranteed to be unique.

• Useful when making class names from a list of files

• bundlesmatching(regex, tag1, ...)• Returns bundles matching criteria

• Result can be used in a methods promise

• Very powerful together with findfiles

bundlesequence - Example

• bundle common global {

vars:

“policies” slist => findfiles

(“/var/cfengine/inputs/*.cf”);

“bundles” slist => bundlesmatching

(“.*”, “production”);

}

body common control {

inputs => { @(global.policies) };

bundlesequence => { @(global.bundles) };

}

New language functions

• Plenty of others• data_readstringarray

• data_readstringarrayidx

• datastate

• datatype

• getclassmetatags

• getvariablemetatags

• max

• mean

• mergedata

• min

• parsejson

• readjson

• storejson

• string_downcase

• string_head

• string_length

• string_reverse

• string_tail

• string_upcase

• variablesmatching

• variance

Tags

Tags

• Labels that you can attach to bundles and promises

• Certain functions can filter based on tags• bundlesmatching

• classesmatching

• variablesmatching

Tags - Example

• bundle agent my_bundle {

meta: ### Bundle tags

“tags” => { “experimental” };

vars: ### Variable tags

“db_server” string => “106.54.21.90”,

meta => { “mysql”, “trusted” };

classes: ### Class tags

“experimental” expression => “any”,

meta => { “tier_spec” };

}

Data containers

Data containers

• Structured containers (JSON)• “container” data => parsejson('[

{ “user”: “joe”, “groups”: “users” },

{ “user”: “jack”, “groups”: “admins” },

]');

• reports:

“$(container[1][user])”;

• --> R: jack

Data containers

• Can read JSON files• readjson(filename, maxbytes)

• Or fields from a text file• data_readstringarray

(filename, comment, split, maxentries, maxbytes)

• data_readstringarrayidx

(filename, comment, split, maxentries, maxbytes)

• Convert back to JSON• storejson(data_container)

Data containers - Example

• records.txt:• joe,/nfs/home/joe,Joe Smith

jack,/home/jack,Jack Jensen

• Resulting JSON after data_readstringarrayidx• [

[ “joe”, “/nfs/home/joe”, “Joe Smith” ],

[ “jack”, “/home/jack”, “Jack Jensen” ]

]

Data containers - Example

• records.txt:• joe,/nfs/home/joe,Joe Smith

jack,/home/jack,Jack Jensen

• policy.cf:• vars:

“users” data => data_readstringarrayidx

(“records.txt”, “”, “,”, 10, 4000);

“index” slist => getindices(“users”);

users:

“$(users[$(index)][0])”

home_dir => “$(users[$(index)][1])”,

description => “$(users[$(index)][2])”,

policy => “present”;

File templating

File templating

• New templating engine: Mustache• Based on the Mustache templating

language• http://mustache.github.io/

File templating - Example

• promises.cf:• files:

"/etc/motd"

edit_line => motd_edit,

edit_defaults => empty;

}

bundle edit_line motd_edit

{

insert_lines:

“Welcome to this CFEngine managed machine.”;

“This machine pulls policy from $(sys.policy_hub).”;

}

• Result:• Welcome to this CFEngine managed machine.

This machine pulls policy from 10.80.80.1.

File templating - Example

• promises.cf:• files:

"/etc/motd"

edit_template => "template.mustache",

template_method => "mustache";

• template.mustache:• Welcome to this CFEngine managed machine.

This machine pulls policy from {{vars.sys.policy_hub}}.

• Result:• Welcome to this CFEngine managed machine.

This machine pulls policy from 10.80.80.1.

Miscellaneous

• cf-serverd allows distinct key/IP/hostname access controls

• New “shortcut” constraint in server policy allows non-absolute paths in copy_from promises

• New log format

• Many new built-in variables:• sys.uptime, sys.masterdir, this.promiser_ppid, ...

• LMDB replaces Tokyo Cabinet as database backend

• Calls to execresult and returnszero are now cached instead of executing repeatedly

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Questions?

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Questions?

• User promises• TLS protocol• Math expressions• Dynamic inputs• New language functions• Tags• Data containers• File templating

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Thank you!