1 comment on “LinuxKit and Three Concerns with Physical Provisioning of Immutable Images”

LinuxKit and Three Concerns with Physical Provisioning of Immutable Images

DR ProvisionAt Dockercon this week, Docker announced an immutable operating system called LinuxKit which is powered by a Packer-like utility called Moby that RackN CTO, Greg Althaus, explains in the video below.

For additional conference notes, check out Rob Hirschfeld’s Dockercon retro blog post.

Three Concerns with Immutable O/S on Physical

With a mix of excitement and apprehension, the RackN team has been watching physical deployment of immutable operating systems like CoreOS Container Linux and RancherOS.  Overall, we like the idea of a small locked (aka immutable) in-memory image for servers; however, the concept does not map perfectly to hardware.

Note: if you want to provision these operating systems in a production way, we can help you!

These operating systems work on a “less is more” approach that strips everything out of the images to make them small and secure.  

This is great for cloud-first approaches where VM size has a material impact in cost.  It’s particularly matched for container platforms where VMs are constantly being created and destroyed.  In these cases, the immutable image is easy to update and saves money.

So, why does that not work as well on physical?

First:  HA DHCP?!  It’s not as great a map for physical systems where operating system overhead is pretty minimal.  The model requires orchestrated rebooting of your hardware.  It also means that you need a highly available (HA) PXE Provisioning infrastructure (like we’re building with Digital Rebar).

Second: Configuration. That means that they must rely on having cloud-init injected configuration.  In a physical environment, there is no way to create cloud-init like injections without integrating with the kickstart systems (a feature of Digital Rebar Provision).  Further, hardware has a lot more configuration options (like hard drives and network interfaces) than VMs.  That means that we need a robust and system-by-system way to manage these configurations.

Third:  No SSH.  Yes another problem with these minimal images is that they are supposed to eliminate SSH.   Ideally, their image and configuration provides everything required to run the image without additional administration.  Unfortunately, many applications assume post-boot configuration.  That means that people often re-enable SSH to use tools like Ansible.  If it did not conflict with the very nature of the “do-not configure-the-server” immutable model, I would suggest that SSH is a perfectly reasonable requirement for operators running physical infrastructure.

In Summary, even with those issues, we are excited about the positive impact this immutable approach can have on data center operations.

With tooling like Digital Rebar, it’s possible to manage the issues above.  If this appeals to you, let us know!

0 comments on “April 21 – Weekly Recap of All Things Site Reliability Engineering (SRE)”

April 21 – Weekly Recap of All Things Site Reliability Engineering (SRE)

Welcome to the weekly post of the RackN blog recap of all things SRE. If you have any ideas for this recap or would like to include content please contact us at info@rackn.com or tweet Rob (@zehicle) or RackN (@rackngo)

SRE Items of the Week

DigitalRebar Provision deploy Docker’s LinuxKit Kubernetes


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Install Digital Rebar PXE Provision on a Mac OSX System and Test Boot using Virtual Box


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Packet Pushers 333 Automation & Orchestration in Networking
http://packetpushers.net/podcast/podcasts/show-333-orchestration-vs-automation/

While the discussion is all about NETWORK DevOps, they do a good job of decrying WHY current state of system orchestration is so sad – in a word: heterogeneity.  It’s not going away because the alternative is lock-in.  They also do a good job of describing the difference between automation and orchestration; however, I think there’s a middle tier  of resource “scheduling” that better describes OpenStack and Kubernetes.

Around 5:00 minutes into the podcast, they effectively describe the composable design of Digital Rebar and the rationale for the way that we’ve abstracted interfaces for automation.  If you guys really do want to cash in by consulting with it (at 10 minutes), just contact Rob H.
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Digital Magazine Launch: Increment On-Call
https://increment.com/on-call/

Increment is dedicated to covering how teams build and operate software systems at scale, one issue at a time. In this, our inaugural issue, we focus on industry best practices around on-call and incident response.
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Need PXW? Try out this Cobbler Replacement
https://robhirschfeld.com/2017/04/11/provision-preview/ 

INTRO
We wanted to make open basic provisioning API-driven, secure, scalable and fast.  So we carved out the Provision & DHCP services as a stand alone unit from the larger open Digital Rebar project.  While this Golang service lacks orchestration, this complete service is part of Digital Rebar infrastructure and supports the discovery boot process, templating, security and extensive image library (Linux, ESX, Windows, … ) from the main project.

TL;DR: FIVE MINUTES TO REPLACE COBBLER?  YES.

The project APIs and CLIs are complete for all provisioning functions with good Swagger definitions and docs.  After all, it’s third generation capability from the Digital Rebar project.  The integrated UX is still evolving.
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UPCOMING EVENTS

Rob Hirschfeld and Greg Althaus are preparing for a series of upcoming events where they are speaking or just attending. If you are interested in meeting with them at these events please email info@rackn.com.

DevOpsDays Austin : May 4-5, 2017 in Austin TX  

OpenStack Summit : May 8 – 11, 2017 in Boston, MA  

  • OpenStack and Kubernetes. Combining the best of both worlds – Kubernetes Day  

Interop ITX : May 15 – 19, 2017 in Las Vegas, NV

Gluecon : May 24 – 25, 2017 in Denver, CO

  • Surviving Day 2 in Open Source Hybrid Automation – May 23, 2017 : Rob Hirschfeld and Greg Althaus

OTHER NEWSLETTERS

SRE Weekly (@SREWeekly)Issue #68

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