This talk will introduce new CFEngine 3.6 features, we have these bullet points: User promises TLS protocol Math expressions Dynamic inputs New language functions Tags Data containers File templating Presentation by Kristian Amlie of CFEngine, given at CfgMgmtCamp 2014 in Ghent

1. What is new in
CFEngine 3.6
www.cfengine.com

2. What is new
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User promises
TLS protocol
Math expressions
Dynamic inputs
New language functions
Tags
Data containers
File templating

3. User promises

4. User promises
• A new promise type
• Manage local users on hosts
• Make promises about user
characteristics
• UID
• Group membership
• Home directory
• Password
• Shell
• Description

5. 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”);
}

6. TLS protocol

7. TLS protocol
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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

8. Math expressions

9. 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

10. 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

11. Dynamic inputs

12. 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”;
}

13. Dynamic inputs - Example
• promises.cf
body common control {
inputs => { “input_file.cf” };
}
• input_file.cf
body file control {
inputs => { “nested_input_file.cf” };
}

14. New language
functions

15. 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

16. 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

17. bundlesequence - Example
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bundle common global {
vars:
“policies” slist => findfiles
(“/var/cfengine/inputs/*.cf”);
“bundles” slist => bundlesmatching
(“.*”, “production”);
}
body common control {
inputs => { @(global.policies) };
bundlesequence => { @(global.bundles) };
}

18. New language functions
• Plenty of others
• data_readstringarray
• readjson
• data_readstringarrayidx
• storejson
• datastate
• string_downcase
• datatype
• string_head
• getclassmetatags
• string_length
• getvariablemetatags
• string_reverse
• max
• string_tail
• mean
• string_upcase
• mergedata
• variablesmatching
• min
• variance
• parsejson

19. Tags

20. Tags
• Labels that you can attach to bundles
and promises
• Certain functions can filter based on tags
• bundlesmatching
• classesmatching
• variablesmatching

21. Tags - Example
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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” };
}

22. Data containers

23. Data containers
• Structured containers (JSON)
• “container” data => parsejson('[
{ “user”: “joe”,
“groups”: “users” },
{ “user”: “jack”, “groups”: “admins” },
]');
• reports:
“$(container[1][user])”;
• --> R: jack

24. 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)

25. Data containers - Example
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records.txt:
• joe,/nfs/home/joe,Joe Smith
jack,/home/jack,Jack Jensen
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Resulting JSON after data_readstringarrayidx
• [
[ “joe”, “/nfs/home/joe”, “Joe Smith” ],
[ “jack”, “/home/jack”, “Jack Jensen” ]
]

26. Data containers - Example
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records.txt:
• joe,/nfs/home/joe,Joe Smith
jack,/home/jack,Jack Jensen
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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”;

27. File templating

28. File templating
• New templating engine: Mustache
• Based on the Mustache templating
language
• http://mustache.github.io/

29. 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.

30. 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.

31. Miscellaneous
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cf-serverd allows distinct key/IP/hostname access
controls
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New “shortcut” constraint in server policy allows non-absolute
paths in copy_from promises
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New log format
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Many new built-in variables:
• sys.uptime, sys.masterdir, this.promiser_ppid, ...
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LMDB replaces Tokyo Cabinet as database backend
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Calls to execresult and returnszero are now cached
instead of executing repeatedly

32. Questions?
www.cfengine.com

33. Questions?
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User promises
TLS protocol
Math expressions
Dynamic inputs
New language functions
Tags
Data containers
File templating
www.cfengine.com

34. Thank you!
www.cfengine.com