Amazon Elastic Load Balancing (ELB) is pretty cool

Using this service costs $0.025/hour so it may make sense to just run HAProxy yourself on a EC2 instance, but then you have to worry about fault tolerance/recovery if that instance fails. The ELB cost is small in comparison to running a cluster of EC2 instances and "outsourcing" as much of your system as possible to AWS (e.b., SimpleDB, Elastic Load Balancing, Relational Database Server, EBS, etc.) can certainly reduce both the complexity of your application architecture and also your implementation costs.

Here are my notes for a simple ELB setup for an AMI that contains a Rails web application:
export EC2_PRIVATE_KEY=pk-....pem  # different on your system
export EC2_CERT=/Users/markw/.ec2/cert-...pem  # different on your system

ec2run -k gsg-keypair  ami-e767ds71
ec2run -k gsg-keypair  ami-e767ds71

Note: specifying "gsg-keypair" matches later doing ssh -i ~/.ssh/id_rsa-gsg-keypair ...

elb-create-lb  MarkTest123 --headers --listener "lb-port=80,instance-port=4242,protocol=HTTP" --availability-zones us-east-1b

elb-configure-healthcheck  MarkTest123 --headers --target "HTTP:4242/ping" --interval 30 --timeout 3 --unhealthy-threshold 2 --healthy-threshold 2

elb-register-instances-with-lb  MarkTest123  --headers --instances i-X,i-Y

* substitute real EC2 IDs for i-X and i-Y, and this works great!

ssh -i ~/.ssh/id_rsa-gsg-keypair ubuntu@ec2-63-212-55-241.compute-1.amazonaws.com
create a file public/ping    - put a line of text in it
start Rails on port 4242

* note: repeat for other EC2 instance. In production, obviously you would want to start your Rails apps using /etc/init.d/...

Then, hitting this URL works: http://marktest123-1645979628.us-east-1.elb.amazonaws.com

Teardown:

elb-delete-lb MarkTest123
and delete EC2 instances
It took me a little while to get ELB working, so I hope that my notes save you some time.

Comments

  1. Shlomo1:41 AM

    Thanks for spelling out these steps clearly.

    You'll want to create a DNS CNAME alias pointing, say, www.marktest.com to marktest123-1645979628.us-east-1.elb.amazonaws.com .

    For some deep-dive detail into how ELB works and how to test that it's scaling for you, see my article here:

    http://clouddevelopertips.blogspot.com/2009/07/elastic-in-elastic-load-balancing-elb.html

    ReplyDelete

Post a Comment

Popular posts from this blog

Ruby Sinatra web apps with background work threads

In Java-land, I have often used the pattern of writing a servlet with an init() method that starts up one or more background work threads. Then while my web application is handling HTTP requests the background threads can be doing work like fetching RSS feeds for display in the web app, perform periodic maintenance like flushing old data from a database, etc. This is a simple pattern that is robust and easy to implement with a few extra lines of Java code and an extra servlet definition in a web.xml file. In Ruby-land this pattern is even simpler to implement: require 'rubygems' require 'sinatra' $sum = 0 Thread.new do # trivial example work thread while true do sleep 0.12 $sum += 1 end end get '/' do "Testing background work thread: sum is #{$sum}" end While the main thread is waiting for HTTP requests the background thread can do any other work. This works fine with Ruby 1.8.7 or any 1.9.*, but I would run this in JRuby for a lon
Read more

My Dad's work with Robert Oppenheimer and Edward Teller

Robert Oppenheimer and Edward Teller facilitated my Dad getting a professorship at UC Berkeley when I was 3 years old. Oppenheimer left Berkeley but Teller was a good friend of my father and I remember him being in our home. Three weeks ago, my wife and I were just leaving to see the new Oppenheimer movie when my Dad called. He mentioned that when I was in grade school he was invited to give a talk at Princeton. After his talk Oppenheimer talked with my Dad and invited him to have dinner at his house. My Dad said Oppenheimer was not well (I think he died of throat cancer soon afterwards) but his wife Kitty carried the conversation. My Dad, Ken Watson, passed away 10 days ago on August 18, 2023.
Read more

Time and Attention Fragmentation in Our Digital Lives

  As humans we have evolved over a few million years to be both attentive and reactive to danger, live in social communities, and spend much of our time being in the present moment gathering and eating food and socializing. The behavior of rapidly changing short attention to content on social media, too many good short form things to watch on streaming video entertainment platforms, are all rewiring our brains in an unnatural and unhealthy way. I fight back, but in really simple ways that entail little ceremony: Almost every morning I spend 30 minutes scanning Hacker News (about 10 minutes), Apple News (about 5 minutes), and the remaining time on Twitter and Mastodon finding interesting new (mostly tech) things. I make notes in a temporary Apple Note: links of things I may want to research, try, or simply read that day. I like to get this all done at once, and then not feel like I need to interrupt my activities during the day to “catch up” on what is happening in the world. In a way,
Read more