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Eric Simmerman
 

Configure my Amazon EC2 instances to only accept traffic from the Elastic Load Balancer

The AWS Elastic Load Balancing FAQ has this very relevant question:

Can I configure my Amazon EC2 instances to only accept traffic from the Elastic Load Balancer?

followed by an ever so helpful response:

Yes.

Seriously - no links, no reference to documentation, nothing. With such a tremendous investment in infrastructure you'd think Amazon might spend a day or two on documentation...alas.

Insult to injury it's also not at all obvious what you need to do to configure your Security Group to support this very commonly desired configuration. I'm here to help.

Use the not-so-documented 'amazon-elb/amazon-elb-sg' Security Group name as the Inbound Source for your Security Group rule to filter on traffic coming from your AWS ELB. Enjoy!

Posted by Eric Simmerman
 

Resolving git-gc error on Mac

During today's maintenance run of git-gc on our Mac hosted repo I encountered screenfulls of nasty fatal error messages - but the last two were a clue to the root cause:

fatal: Unable to create temporary file: Too many open files
error: failed to run repack

This related post helped me find a quick cure which involved simply bumping the ulimit up temporarily.

# ulimit -n 10024
> git gc

Easy fix for a potentially bad day.

Posted by Eric Simmerman
 

Play framework on AWS

Steps I took to get a Play framework app up and running on a micro AWS instance running Ubuntu 11.10

  1. sudo add-apt-repository "deb http://archive.canonical.com/ lucid partner"
  2. sudo apt-get update
  3. sudo apt-get install sun-java6-jdk unzip
  4. wget http://download.playframework.org/releases/play-1.2.4.zip
  5. sudo unzip play-1.2.4.zip -d /usr/local/share/
  6. install Dominik Dorn's startup script
    1. wget https://raw.github.com/gist/1290012/a31b1d079705ea7ccf6d1fdc866027b674e62841/...
    2. sudo mv playframework /etc/init/
    3. update the script with proper paths 
  7. useradd username -g www-data -m -d /home/username -s /bin/bash
  8. install your app
  9. initctl start playframework
Posted by Eric Simmerman
 

Install APC on CentOS 5.6

The following resolved a few gotchas I encountered installing APC on an old instance of CentOS 5.6

  1. mount -o remount,exec /tmp
  2. yum install pcre-devel
  3. pecl install apc
  4. mount -o remount,noexec /tmp
Posted by Eric Simmerman
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