ncf - a powerful and structured CFEngine framework
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Normation – CC-BY-SA normation.com ncf A powerful and structured CFEngine framework Jonathan CLARKE – [email protected] @jooooooon42 (that's 7 'o's)
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After 4 years of "experience in the trenches" providing enterprise configuration management solutions based on CFEngine 3, it became clear that our customers wanted CFEngine's speed, small footprint, and features but were having a hard time with the language and tooling, and needed an easier way. The goal of ncf is to abstract the knowledge of "how" to achieve tasks in CFEngine, and expose these capabilities for non-expert users. Thus, you can express your intent in a very succinct and expressive manner, integrating simply with CFEngine and its power, while keeping everything "under the hood" tunable. ncf promotes DRY-ness and sharing knowledge. It is built from the ground-up to be easy to learn, flexible and extensible. The framework is written in pure CFEngine language, introducing a well-structured design built on multiple decoupled layers with clearly-defined interfaces and roles. In our presentation we will introduce ncf and explain how ncf can be used to solve real-world examples, explain our design choices, the architectural approach taken, and demo the new magic at our finger tips to build CFEngine solutions that are extensible and easier to work with.
Transcript of ncf - a powerful and structured CFEngine framework
Normation – CC-BY-SAnormation.com
ncf
A powerful and structuredCFEngine framework
Jonathan CLARKE – [email protected]@jooooooon42 (that's 7 'o's)
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ncfwww.ncf.io
Who am I?
● Jonathan Clarke
● Title: Co-founder & Product lead at Normation
● Origins: Sysadmin, infrastructure management
● Now: Automation + “running a company”-stuff
● Contributor to free software:
– Co-creator of Rudder
– Contributor to CFEngine, OpenLDAP
● Co-organizer of events:
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ncfwww.ncf.io
Intro
This presentationis about cakes
Photo CC BY 2.0 from http://www.flickr.com/photos/misscreativecakes/
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Intro
Reminder: how are cakes made?
1. Ingredients
+2. Recipes
Photo CC BY-NC 2.0 from http://www.flickr.com/photos/tnemily/
Photo CC BY 2.0 from http://www.flickr.com/photos/misscreativecakes/
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ncfwww.ncf.io
Background
A bunch ofCFEngine consultants
● > 4 years● Multiple companies: small, large & huge● Various uses: security, provisioning, DR...
We always got the same feedback
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Feedback #1: CFEngine rocks!
CFEngine rocksMulti-platformLinux, Android, BSD, AIX, HP-UX, Solaris, Windows...
Open SourceGPLv3
Small footprint, scalableA few MB of RAM,just seconds to run...
Continuous checkingAgent based approach,no push
Resilient to errorsNetwork outages, failures,unavailable resources...
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Feedback #2: CFEngine is hard!
CFEngine is hard
Too much “do it yourself”Building your own policy structure from blank slate
Steep learning curveSyntax is unusual, hardto learn and understand
Lack of feedbackOutput is hard to read,“what is going on?”
Workarounds for bugsNo way of systematically using a workaround
“Flour, eggs, milk and butter”As in: https://digitalelf.net/2013/04/a-case-study-in-cfengine-layout/
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Feedback #2: CFEngine is hard!
Learning to bake cakes on your own is frustrating.
Photo CC BY-NC-SA 2.0 from http://www.flickr.com/photos/penguincakes/
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Brief dilemma...
Can we fix this?
We've worked around this for customers, let's make it reusable!
CHALLENGE ACCEPTED.
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Approach
Too much do it yourselfBuilding your own policy structure from blank slate
1) Provide a structured layout to start from
2) Provide single-purpose, reusable “methods” to get the basics done
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ncfwww.ncf.io
Steep learning curveSyntax is unusual, hardto learn and understand
Approach
1) Hide the weirder syntaxinside these reusable “methods”
2) Only require a subset of syntaxto write everyday policies (method calls)
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Approach
1) Implement workarounds into those reusable “methods” (and use them)
2) Automated tests to make sure the bugs don't “come back”
Workarounds for bugsNo way of systematically using a workaround
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Lack of feedbackOutput is hard to read,“what is going on?”
Approach
1) Now everything goes through reusable “methods”, build automatic feedback in
2) Make the feedback format customisable and extensible
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Result
“Forget baking,I'm gonna get some
cakes from the shop”Photo CC BY-NC-SA 2.0 from http://www.flickr.com/photos/omarsc/
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Result
We created ncf
ncf is a frameworkthat runs in pure CFEngine language,to help structure CFEngine policy and
provide reusable, single purpose components distributed under the GPLv3 license.
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Result
Example === 1000 words
With ncf:
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Result
Example === 1000 wordsWithout ncf:
This is actuallyover-simplified:- No feedback- No exceptions for different OSes- No advanced options
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Result
Example === 1000 words
With ncf, automatic feedback:R: [DEBUG] Promise kept, not doing anything: Install package ntp in version latestR: [INFO] Promise repaired, made a change: Build file /etc/ntp.conf from template ntp.confR: [INFO] Promise repaired, made a change: Restart service ntpR: [DEBUG] Promise kept, not doing anything: Ensure that service ntp is running
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How does it work?
How does it work?CFEngine 3 can have self-contained “bundles” that you can call with parameters.
ntp
logger
package_install file_from_template service_restart
Outputs structured messages
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A layered approach
A layered approachServices
Techniques
IT Ops Knowledge
Generic methods
CFEngine basics
ncf internals
IT services: “Corporate web site”
Components of services: “Apache”
Shared information: “httpd” package name
Unit tasks: “Copy file”, “Install package”
CFEngine standard libraries
Framework config and magic :)
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ncfwww.ncf.io
A layered approach
A layered approachServices
Techniques
IT Ops Knowledge
Generic methods
CFEngine basics
ncf internals
IT services: “Corporate web site”
Components of services: “Apache”
Shared information: “httpd” package name
Unit tasks: “Copy file”, “Install package”
CFEngine standard libraries
Framework config and magic :)
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Each generic_method does one thing and one thing only
Philosophy
Core principles
Objective not subjective
KISSDRY
ExtensibleOpen source
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Available generic_methods
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Online documentation
http://www.ncf.io/pages/reference.html
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Current status
Project is young, but robustNeed more generic methods
Ohloh statistics:
Source: http://www.ohloh.net/p/ncf-project
Actually CFEngine
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Questions?
Check it out on:http://www.ncf.io/
Jonathan CLARKE – [email protected]@jooooooon42 (that's 7 'o's)
