ncf A powerful and structured CFEngine framework Jonathan CLARKE - - PowerPoint PPT Presentation

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ncf A powerful and structured CFEngine framework Jonathan CLARKE - - PowerPoint PPT Presentation

Aug 23, 2022 372 likes •682 views

ncf A powerful and structured CFEngine framework Jonathan CLARKE jcl@normation.com @jooooooon42 (that's 7 'o's) Normation CC-BY-SA normation.com ncf Who am I? www.ncf.io Jonathan Clarke Title: Co-founder & Product lead at

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ncf

A powerful and structured CFEngine framework

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

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www.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 presentation is 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 of CFEngine 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 rocks

Multi-platform Linux, Android, BSD, AIX, HP-UX, Solaris, Windows... Open Source GPLv3 Small footprint, scalable A few MB of RAM, just seconds to run... Continuous checking Agent based approach, no push Resilient to errors Network 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 curve Syntax is unusual, hard to learn and understand Lack of feedback Output is hard to read, “what is going on?” Workarounds for bugs No 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 yourself Building 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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www.ncf.io Steep learning curve Syntax is unusual, hard to learn and understand

Approach

1) Hide the weirder syntax inside these reusable “methods” 2) Only require a subset of syntax to 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 bugs No way of systematically using a workaround

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www.ncf.io Lack of feedback Output 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 framework that 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 words

Without ncf:

This is actually

  • ver-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 latest R: [INFO] Promise repaired, made a change: Build file /etc/ntp.conf from template ntp.conf R: [INFO] Promise repaired, made a change: Restart service ntp R: [DEBUG] Promise kept, not doing anything: Ensure that service ntp is running

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A layered approach

A layered approach

Services Techniques

IT services: “Corporate web site” Components of services: “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

  • ne thing and one thing only

Philosophy

Core principles

Objective not subjective

KISS DRY

Extensible Open 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 robust Need 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 cherry

  • n 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 methods Build 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)