Random thoughts of a warped mind…

September 17, 2014

Reconfig for service discovery

Filed under: Amazon EC2,Chef,Git,Linux,Redhat OpenShift,Ruby,Virtualization — Srinivas @ 09:49

Imagine a constantly changing fleet of servers… New servers (or virtual machines) going online as capacity is needed or being taken offline as load drops… Maybe you already use Chef/Puppet to bootstrap your servers and use their node attributes to populate N servers in a load balancer (Haproxy for example) configuration. 

Now adding/removing a new server (a backend, maybe a rails/tomcat server, whatever) would mean that chef-client has to run on all the haproxy boxes so they know about the new backend (or the one that went away). This would work if you  run chef-client every 5 minutes or so? But why? Chef/Puppet are primarily meant to bootstrap your servers and not to sync state. Enter Reconfig and service discovery.

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February 12, 2014

Sync S3 buckets in parallel mode via concurrent threads

Filed under: All,Amazon EC2,EC2,Git,Ruby,S3 — Srinivas @ 18:13

A week back I realized one of my core S3 buckets at work (which we use for all a bunch of app uploads that are always needed) was a us-west-2 only bucket and not US-Standard. (Dont like that, When S3 gives you 11 9s why not get a US Standard bucket???). Considering that we had varnish in multiple regions with this bucket as the backend, I wanted to do two things -

1. Migrate all data from this bucket to a US-Standard bucket

2. Migrate all data from this bucket to a EU/Ireland bucket as well (coz I have app servers etc out there as well which need the same data – Did’nt want to come across the pond for every object we had to retrieve). Why? Reduced latency and reduced B/W costs (costs nothing when a EC2 instance in EU has to pull an object from a EU bucket).

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August 2, 2013

Cloudfront woes – “Your request contains one or more invalid invalidation paths.” – Use custom regexp for URI::encode

Filed under: All,Amazon EC2,EC2,Linux,Ruby — Srinivas @ 12:27

AWS Cloudfront is a content delivery network part of Amazons EC2/AWS stack which lets you serve static assets from a source (S3 bucket or custom origin server) by caching it across numerous edge locations. Occassionally the underlying content can change which needs the cache to be refreshed – This is done via a Cloudfront cache invalidation request which specifies a distribution id and a list of paths to refresh (e.g. /index.html or /imgs/logo.png etc).

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May 30, 2013

Source config info from a Chef data bag in a knife executable script

Filed under: Amazon EC2,Chef,EC2,Ruby — Srinivas @ 03:59

Its nice not to have to hardcode config info into multiple scripts – A clean way to do this is to use Knife data bags . This way config information can be shared between cookbooks run on chef managed instances as well as used in one-off scripts run from your chef management box.

The trick is to use ‘Chef::DataBagItem’ in your script and execute this script via “knife exec scriptname.rb”. This means that the execution of this script will use your chef login info to access your chef server, access the data bag and pull the keys from it into your local script.

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May 24, 2013

Sinatra app on Redhats OpenShift PaaS

Filed under: Development,EC2,Git,Linux,Redhat OpenShift,Ruby,Virtualization — Srinivas @ 02:08

Got to poke around a bit today into Redhats Open Shift PaaS… This is quite similar to Herokus platform in the sense you could pick up a “dev platform”, build an app locally and push it to the PaaS and run it from there…

For the impatient, rush over to the App on Openshift and  pull the code from github

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