Monthly Archives: February 2010

A Case For Images

After speaking with Luke Kanies at OpsCamp, and reading his good and oft-quoted article “Golden Image or Foil Ball?“, I was thinking pretty hard about the use of images in our new automated infrastructure.  He’s pretty against them.  After careful consideration, however, I think judicious use of images is the right thing to do.

My top level thoughts on why to use images.

  1. Speed – Starting a prebuilt image is faster than reinstalling everything on an empty one.  In the world of dynamic scaling, there’s a meaningful difference between a “couple minute spinup” and a “fifteen minute spinup.”
  2. Reliability – The more work you are doing at runtime, the more there is to go wrong.  I bet I’m not the only person who has run the same compile and install on three allegedly identical Linux boxen and had it go wrong somehow on one of ’em.  And the more stuff you’re pulling to build your image, the more failure points you have.
  3. Flexibility – Dynamically building from stem cell kinda makes sense if you’re using 100% free open source and have everything automated.  What if, however, you have something that you need to install that just hasn’t been scripted – or is very hard to script?  Like an install of some half-baked Windows software that doesn’t have a command line installer and you don’t have a tool that can do it?  In that case, you really need to do the manual install in non-realtime as part of a image build.  And of course many suppliers are providing software as images themselves nowadays.
  4. Traceability – What happens if you need to replicate a past environment?  Having the image is going to be a 100% effective solution to that, even likely to be sufficient for legal reasons.  “I keep a bunch of old software repo versions so I can mostly build a machine like it” – somewhat less so.

In the end, it’s a question of using intermediate deliverables.  Do you recompile all the code and every third party package every time you build a server?  No, you often use binaries – it’s faster and more reliable.  Binaries are the app guys’ equivalent of “images.”

To address Luke’s three concerns from his article specifically:

  1. Image sprawl – if you use images, you eventually have a large library of images you have to manage.  This is very true – but you have to manage a lot of artifacts all up and down the chain anyway.  Given the “manual install” and “vendor supplied image” scenarios noted above, if you can’t manage images as part of your CM system than it’s just not a complete CM system.
  2. Updating your images – Here, I think Luke makes some not entirely valid assumptions.  He notes that once you’re done building your images, you’re still going to have to make changes in the operational environment (“bootstrapping”).  True.  But he thinks you’re not going to use the same tool to do it.  I’m not sure why not – our approach is to use automated tooling to build the images – you don’t *want* to do it manually for sure – and Puppet/Chef/etc. works just fine to do that.  So if you have to update something at the OS level, you do that and let your CM system blow everything on top – and then burn the image.  Image creation and automated CM aren’t mutually exclusive – the only reason people don’t use automation to build their images is the same reason they don’t always use automation on their live servers, which is “it takes work.”  But to me, since you DO have to have some amount of dynamic CM for the runtime bootstrap as well, it’s a good conservation of work to use the same package for both. (Besides bootstrapping, there’s other stuff like moving content that shouldn’t go on images.)
  3. Image state vs running state – This one puzzles me.  With images, you do need to do restarts to pull in image-based changes.  But with virtually all software and app changes you have to as well – maybe not a “reboot,” but a “service restart,” which is virtually as disruptive.  Whether you “reboot  your database server” or “stop and start your database server, which still takes a couple minutes”, you are planning for downtime or have redundancy in place.  And in general you need to orchestrate the changes (rolling restarts, etc.) in a manner that “oh, pull that change whenever you want to Mr. Application Server” doesn’t really work for.

In closing, I think images are useful.  You shouldn’t treat them as a replacement for automated CM – they should be interim deliverables usually generated by, and always managed by, your automated CM.  If you just use images in an uncoordinated way, you do end up with a foil ball.  With sufficient automation, however, they’re more like Russian nesting dolls, and have advantages over starting from scratch with every box.

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Agile Operations

It’s funny.  When we recently started working on an upgrade of our Intranet social media platform, and we were trying to figure out how to meld the infrastructure-change-heavy operation with the need for devs, designers, and testers to be able to start working on the system before “three months from now,” we broached the idea of “maybe we should do that in iterations!”  First, get the new wiki up and working.  Then, worry about tuning, switching the back end database, etc.  Very basic, but it got me thinking about the problem in terms of “hey, Infrastructure still operates in terms of waterfall, don’t we.”

Then when Peco and I moved over to NI R&D and started working on cloud-based systems, we quickly realized the need for our infrastructure to be completely programmable – that is, not manually tweaked and controlled, but run in a completely automated fashion.  Also, since we were two systems guys embedded in a large development org that’s using agile, we were heavily pressured to work in iterations along with them.  This was initially a shock – my default project plan has, in traditional fashion, months worth of evaluating, installing, and configuring various technology components before anything’s up and running.   But as we began to execute in that way, I started to see that no, really, agile is possible for infrastructure work – at least “mostly.”  Technologies like cloud computing help, but there’s still a little more up front work required than with programming – but you can get mostly towards an agile methodology (and mindset!).

Then at OpsCamp last month, we discovered that there’s been this whole Agile Operations/Automated Infrastructure/devops movement thing already in progress we hadn’t heard about.  I don’t keep in touch with The Blogosphere ™ enough I guess.  Anyway, turns out a bunch of other folks have suddenly come to the exact same conclusion and there’s exciting work going on re: how to make operations agile, automate infrastructure, and meld development and ops work.

So if  you also hadn’t been up on this, here’s a roundup of some good related core thoughts on these topics for your reading pleasure!

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Enterprise Systems vs. Agility

I was recently reading a good Cameron Purdy post where he talks about his eight theses regarding why startups or students can pull stuff off that large enterprise IT shops can’t.

My summary/trenchant restatement of his points:

  1. Changing existing systems is harder than making a custom-built new one (version 2 is harder)
  2. IT veterans overcomplicate new systems
  3. The complexity of a system increases exponentially the work needed to change it (versions 3 and 4 are way way harder)
  4. Students/startups do fail a lot, you just don’t see those
  5. Risk management steps add friction
  6. Organizational overhead (paperwork/meetings) adds friction
  7. Only overconservative goons work in enterprise IT anyway
  8. The larger the org, the more conflict

Though I suspect #1 and #3 are the same, #2 and #5 are the same, and #6 and #8 are the same, really.

I’ve been thinking about this lately with my change from our enterprise IT Web site to a new greenfield cloud-hosted SaaS product in our R&D organization.  It’s definitely a huge breath of fresh air to be able to move fast.  My observations:


The problem of systems complexity (theses #1 and #3) is a very real one.  I used to describe our Web site as having reached “system gridlock.”  There were hundreds of apps running dozens to a server with poorly documented dependencies on all kinds of stuff.  You would go in and find something that looked “wrong” – an Apache config, script, load balancer rule, whatever – but if you touched it some house of cards somewhere would come tumbling down.  Since every app developer was allowed to design their own app in its own tightly coupled way, we had to implement draconian change control and release processes in an attempt to stem the tide of people lining up to crash the Web site.

We have a new system design philosophy for our new gig which I refer to as “sharing is the devil.”  All components are separated and loosely coupled.  Using cloud computing for hardware and open source for software makes it easy and affordable to have a box that does “only one thing.”  In traditional compute environments there’s pressure to “use up all that CPU before you add more”, which results in a penny wise, pound foolish strategy of consolidation.  More and more apps and functions get crunched closer together and when you go back to pull them out you discover that all kinds of new connections and dependencies have formed unbidden.


Overcomplicating systems (#2 and #5) can be somewhat overcome by using agile principles.  We’ve been delving heavily into doing not just our apps but also our infrastructure according to an agile methodology.  It surfaces your requirements – frankly, systems people often get away with implementing whatever they want, without having a spec let alone one open to review.  Also, it makes you prioritize.  “Whatever you can get done in this two week iteration, that’s what you’ll have done, and it should be working.”  It forces focus on what is required to get things to work and delays more complex niceties till later as there’s time.


Both small and large organizations can suffer from #6 and #8.  That’s mostly a mindset issue.  I like to tell the story about how we were working on a high level joint IT/business vision for our Web site.  We identified a number of “pillars” of the strategy we were developing – performance, availability, TCO, etc.  I had identified agility as one, but one of the application directors just wasn’t buying into it.  “Agility, that’s weird, how do we measure that, we should just forget about it.”  I finally had to take all the things we had to the business head of the Web and say “of these, which would you say is the single most important one?”  “Agility, of course,” he said, as I knew he would.  I made it a point to train my staff that “getting it done” was the most important thing, more important than risk mitigation or crossing all the t’s and dotting all the i’s.  That can be difficult if the larger organization doesn’t reward risk and achievement over conservatism, but you can work on it.

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OpsCamp Debrief

I went to OpsCamp this last weekend here in Austin, a get-togther for Web operations folks specifically focusing on the cloud, and it was a great time!  Here’s my after action report.

The event invite said it was in the Spider House, a cool local coffee bar/normal bar.  I hadn’t been there before, but other people that had said “That’s insane!  They’ll never fit that many people!  There’s outside seating but it’s freezing out!”  That gave me some degree of trepidation, but I still racked out in time to get downtown by 8 AM on a Saturday (sigh!).  Happily, it turned out that the event was really in the adjacent music/whatnot venue also owned by Spider House, the United States Art Authority, which they kindly allowed us to use for free!  There were a lot of people there; we weren’t overfilling the place but it was definitely at capacity, there were near 100 people there.

I had just hears of OpsCamp through word of mouth, and figured it was just going to be a gathering of local Austin Web ops types.  Which would be entertaining enough, certainly.  But as I looked around the room I started recognizing a lot of guys from Velocity and other major shows; CEOs and other high ranked guys from various Web ops related tool companies.  Sponsors included John Willis and Adam Jacob (creator of Chef) from Opscode , Luke Kanies from Reductive Labs (creator of Puppet), Damon Edwards and Alex Honor from DTO Solutions (formerly ControlTier), Mark Hinkle and Matt Ray from Zenoss, Dave Nielsen (CloudCamp), Michael Coté (Redmonk), Bitnami, Spiceworks, and Rackspace Cloud.  Other than that, there were a lot of random Austinites and some guys from big local outfits (Dell, IBM).

You can read all the tweets about the event if you swing that way.

OpsCamp kinda grew out of an earlier thing, BarCampESM, also in Austin two years ago.  I never heard about that, wish I had.

How It Went

I had never been to an “unconference” before.  Basically there’s no set agenda, it’s self-emergent.  It worked pretty well.  I’ll describe the process a bit for other noobs.

First, there was a round of lightning talks.  Brett from Rackspace noted that “size matters,” Bill from Zenoss said “monitoring is important,” and Luke from Reductive claimed that “in 2-4 years ‘cloud’ won’t be a big deal, it’ll just be how people are doing things – unless you’re a jackass.”

Then it was time for sessions.  People got up and wrote a proposed session name on a piece of paper and then went in front of the group and pitched it, a hand-count of “how many people find this interesting” was taken.

Candidates included:

  • service level to resolution
  • physical access to your cloud assets
  • autodiscovery of systems
  • decompose monitoring into tool chain
  • tool chain for automatic provisioning
  • monitoring from the cloud
  • monitoring in the cloud – widely dispersed components
  • agent based monitoring evolution
  • devops is the debil – change to the role of sysadmins
  • And more

We decided that so many of these touched on two major topics that we should do group discussions on them before going to sessions.  They were:

  • monitoring in the cloud
  • config mgmt in the cloud

This seemed like a good idea; these are indeed the two major areas of concern when trying to move to the cloud.

Sadly, the whole-group discussions, especially the monitoring one, were unfruitful.  For a long ass time people threw out brilliant quips about “Why would you bother monitoring a server anyway” and other such high-theory wonkery.  I got zero value out of these, which was sad because the topics were crucially interesting – just too unfocused; you had people coming at the problem 100 different ways in sound bytes.  The only note I bothered to write down was that “monitoring porn” (too many metrics) makes it hard to do correlation.  We had that problem here, and invested in a (horrors) non open-source tool, Opnet Panorama, that has an advanced analytics and correlation engine that can make some sense of tens of thousands of metrics for exactly that reason.


There were three sessions.  I didn’t take many notes in the first one because, being a Web ops guy, I was having to work a release simultaneously with attending OpsCamp 😛

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