Friday, November 29, 2013

Acer Chromebook C720 Review

I just received my new Acer Chromebook.  After reading the reviews and checking it out at Best Buy, I pulled the trigger and ordered the $199 2GB Acer Chromebook C720.  This is the new Acer Chromebook based on the Intel Celeron with the Haswell Architecture.  The new Chromebook sports lower power consumption and better performance than the previous Acer C710. Here are my impressions of the C720 after a few days of working with it.

I'll cover some pros and cons, and give you some helpful tips.  For those unfamiliar with Chromebooks I'll discuss why you should consider a Chromebook instead of spending more money on a Windows laptop.  As a testimonial to what you can do with the Chromebook, I was able to write this blog entry completely using the Acer C720.  It allowed me to upload screen shots and even edit the pictures using the Pixlr app.

Saturday, November 23, 2013

Evaluating a Bedrock string

I sometimes forget how easy it is to do some things in Bedrock.  Take for example, evaluating a Bedrock expression.

 <pebble $expression>

So how do I create the Bedrock expression?  Ignoring the fact that evaluating strings in a web application is generally something you want to think carefully about since it has the potential to be a security hole, one could construct a string to execute like this:

<sink:expression --htmldecode>&lt;trace --output $env></sink>
<pebble $expression>

By enclosing the string you want to evaluate in a <sink> tag and essentially tricking Bedrock into not recognizing the Bedrock tags by using an HTML entity to start the tag (&lt;), the expression is simply stored as an HTML decoded string.  You can then use the <pebble> tag to execute the string.

In this case, there's not much of a security risk, since you are providing the string to evaluate. But consider:

<textarea name="expression" nrows="10" cols="60">
<var $input.expression>

<if $input.expression>
  <pebble $input.expression>

Allowing execution of arbitrary Bedrock statements is not something you probably want to do.

Sunday, November 17, 2013

AWS re:Invent 2013 - Las Vegas, NV

Quick impressions of AWS re:Invent

Incredible to see Amazon announce all the things that folks are clambering for.  Having said that, if it wasn't obvious before it should be by now.  We benefit from the new products that Amazon creates in two ways. First the amazing fully fleshed out products like their shopping experience, video platform, the new Amazon Workspaces, etc. and the underlying tools they use to create them.  Announcements of note:
  • Kinesis
  • Postgres
  • Amazon Workspaces
  • new instance types (bigger, faster, gaming support)
  • security features that integrate with corporate infrastructure
  • ...and more 
The other cloud players are so far behind at this point it begs the question whether or not Amazon will end up being a monopoly in this space and how will they use that position.  They have always been partners with their customers, so it will be interesting to see how things evolve as it becomes clearer and clearer that Amazon is not just the winner in the space, but may be the only viable player.

AWS CloudFormation - Tips for the Novice (Load balancing with no server affinity)

Look Ma! No Server Affinity!

In this blog entry I present the result of a weekend of messing with CloudFormation.  A load balanced, SSL enabled, Bedrock stack which has an RDS instance to hold session information.  I've removed server affinity requirements by using an RDS instance of MySQL instead of having each web instance implement their own server.

AWS CloudFormation - Tips for the Novice (How to perform a task once per launch - not once per instance)

Here's the issue - we want to launch a stack that includes an RDS database.  We only want to execute some process one time per stack launch, not for each instance.

AWS CloudFormation - Tips for the Novice (create a load balanced stack)

Creating a load balanced stack with ElasticLoadBalancer

Following up on the previous blog post on this subject, we now want to create a load balanced LAMB stack.  The ELB cost is currently $.025.hour.  Do the math:

.025 * 24 * 365 = $219/year

Seems expensive, however the upside is reliability and scalability.  One issue seems to be that the ELB instance does not necessarily handle spikey volume very well according to some reports.  What this means is that under rapidly increasing load, the ELB might not do a great job balancing the traffic.  There are ways to mitigate this however by something called "pre-warming" or apparently begging tech support at Amazon for help.  More research needed...

Saturday, November 16, 2013

AWS CloudFormation - Tips for the Novice (That would be me)

Lot's of talks this week at AWS re:Invent around automation, specifically using the CloudFormation tool, so of course I need to do a deep dive.  First some essential links:
Having four hours to kill between Las Vegas and Philadelphia I decided to start my CloudFormation journey.  I downloaded the CloudFormation docs to my Kindle and started to figure out how to use this product (not an easy task on Spirit Airlines, which has the most uncomfortable seats in the air!  I swear they must steal these seats from planes that have been junked in the desert).  My butt still hurts.

Friday, November 1, 2013

RPM Signing & Package Updating

I'm recording this info to the blog simply to help me to remember how to do this...again.


  • Generate a GPG key
  • Export a public key
  • Import a public key
  • Sign a package
  • Update the Bedrock repo

SSL Certificate Stuff

While mucking with creating an SSL enabled, load balanced, Bedrock stack I needed to create my own certificate and upload it to AWS.