is about cakes - 2014.rmll.info€¦ · feedback #2: cfengine is hard! cfengine is hard too much...

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ncf

A powerful and structuredCFEngine framework

Jonathan CLARKE – jcl@normation.com@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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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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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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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 wordsWith 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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A layered approach

A layered approachServices

Techniques

IT services:“Corporate web site”

Components ofservices: “Apache”

IT Ops Knowledge

Shared information:“httpd” package name

Generic methods

Unit tasks: “Copy file”,“Install package”, ...

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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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Each generic_method does one thing and one thing only

Philosophy

Core principles

Objective not subjective

KISSDRY

ExtensibleOpen source

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Overview of 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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Demo!

(aka “show me the code!”)

Check it out on:http://www.ncf.io/

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The cherry on the cake

The cherryon the cake

Photo CC BY-NC-ND 2.0 from https://www.flickr.com/photos/creativeabubot

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The cherry on the cake

Web interface“ncf builder”

Browse available generic methodsBuild Techniques

Lightweight app (client side HTML+JS)Uses a simple REST API to interact with ncf

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The cherry on the cake

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Questions?

Check it out on:http://www.ncf.io/

Jonathan CLARKE – jcl@normation.com@jooooooon42 (that's 7 'o's)