Configuration Configuration management in memory management in - - PowerPoint PPT Presentation

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Configuration Configuration management in memory management in memory constrained constrained environment environment ___________________________ ___________________________

“Those 8MB of RAM are gonna be a little “Those 8MB of RAM are gonna be a little light for my Ruby stack” light for my Ruby stack”

Matthieu CERDA

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Who are you ?

Name Matthieu CERDA Email : matthieu.cerda@normation.com Web site : http://www.normation.com Twitter : @Kegeruneku Job System engineer at Normation CFEngine Enthusiast, power user and trainer Rudder Integrator, packager Infrastructure Team member

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Configuration management ?

• Enable the user to manage from 0 to ∞ machines:
• Without making mistakes due to repetition
• Without having to provision every machine manually
• Ensuring a common and reliable base

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Effin' embedded systems, how do they work ?

• x86 CPU's are not standard: ARM or MIPS CPUs are kings
• Embedded CPU's aren't war machines: Don't assume you will

have a quad core one

• Low memory: Forget your 8G of RAM
• Everything has a cost: Do not assume your board has a SATA

connector

• Not the same OSes: Goodbye Debian, RHEL or Windows,

welcome OpenWRT, Montavista, VxWorks...

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Examples

• Routers:
• APU 1c
• x86_64 AMD G T40E @ 2x1 GHz
• 2 GB RAM / USB/SD/mSATA
• ALIX 2d13
• x86_32 AMD Geode LX @ 400 MHz
• 256 MB RAM / SD

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Examples

• SOHO Routers:
• FON2303A
• MIPS Ralink 3052 @ 300 MHz
• 64 MB RAM / 8 MB Flash
• TL-MR3020
• MIPS Atheros AR9330 @ 400 MHz
• 32 MB RAM / 4 MB Flash

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Configuration management in embedded environments

• Need to be compatible with memory/CPU constraints
• Problem with complex language stacks
• Hard to use interpreted languages
• Should not be too CPU intensive (SMP will not save you)
• Should be autonomous when possible
• Embedded environments often mean reduced networking

capabilities

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Conventional GNU/Linux OSes

• Your average GNU/Linux OS
• Examples: Debian, Raspbian, Cubian, Fedora, Arch, …
• Provides and extensive library of tools already compiled for

you: the main CM tools are here !

• The most comfortable approach when you need a prototyping

environment, that is affordable and easy to use:

• Boards are cheap
• Boards are legion
• Boards are powerful
• Shameless plug: CubieBoards/BeagleBones rock.

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GNU/Linux based derivatives

• GNU/Linux based, with additionnal constraints
• Examples: OpenWRT, Android / Replicant, MontaVista, ...
• Provide a complete compilation toolchain, but less utilities

already builtin. Documentation is less accessible.

• The work to get CM tools to build is a bit more complicated,

and the lack of packaging / CPU punch makes complex tools harder to impossible to use.

• A Ruby stack is hard to get
• A Python one is decently easy
• C based utilities are easy.
• SOHO routers are the easiest boards to get

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Proprietary software

• Nightmare mode of hobbyists / small companies
• Examples: VxWorks, Windows CE ...
• Provide a limited compilation toolchain, and nearly no open

documentation (NDA's). You're on your own.

• It's basically a plug'n'pray approach, you have to build

everything from scratch.

• No, really. Everything.
• You really don't want to mess with this. If you really want one,

late WRT54G boxes would do the trick (VxWorks).

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Overview of the tools

• 3 families of tools:
• C based: CFEngine, Rudder …
• Ruby based: Puppet, Chef
• Python based: Salt. (Ansible ?)
• Of the three, C is the most efficient approach (CPU, memory

wise) in the embedded world, the other two are usable if the CPU/mem constraints aren't too tight.

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Enough chit chat, time is candy!

• 2 “machines” used for the test
• CubieBoard 1 (A10 ARM CPU, 1GHz, 1 GB RAM)
• Wow, much power, very ARM, such rox.
• QEMU VM (Versatile ARM CPU, 64 MB RAM)
• Not really as powerful. Actually, a LOT less.
• Let's forget storage (NAND flash, HDD, …) constraints for

now.

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Let's get ready to rumble !

• 1st round: CFEngine 3.6.0 vs Puppet 2.7.23
• Idle memory occupation (Cubian)
• Nothing:
• 28 MB
• CFEngine (cf-execd, cf-serverd, cf-monitord):
• 33 MB (+5 MB)
• Puppet (puppetmaster):
• 51 MB (+23 MB)

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Let's get ready to rumble !

• 1st round: CFEngine 3.6.0 vs Puppet 2.7.23
• Memory occupation (Cubian)
• Nothing:
• 28 MB
• CFEngine (cf-agent):
• 37 MB, 10s (+9 MB)
• Puppet (puppet apply):
• 57 MB, 16s (+29 MB)

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Conclusion

• Both tools are reasonably quick to run
• Puppet takes approximately + 20 MB compared to CFEngine
• 64 MB is not enough for Puppet
• Verdict: Configuration management ? Totally on those :) but be

careful, RAM / CPU and time are precious :)

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Questions ? :) Questions ? :)