Keep Your Website Up and Running During an Upgrade

All of us want to have our website up and running.
However, upgrading a software version requires downtime (even if it minimal).
What should we do?

The answer is simple: follow the following process and gain a highly available system based on load balancing and session off loading, as well as a no downtime procedure to upgrade your system.

Keep Your Site Up and Running @ AWS

1. Place more than a single web instance behind a load balancer. The Elastic Load Balancer (ELB) will be fine for that.
2. Make sure you are using session offloading in your system implementation.
3. Install elbcli on your machine sudo apt-get -y install elbcli
4. Create a credentials file /var/keys/aws_credential_file and secure it sudo chmod 600 /var/keys/aws_credential_file
   AWSAccessKeyId=AKIAblablabla
   AWSSecretKey=blablablablablablablablabla
5. Upgrade the servers one after the another.
6. Before upgrading a server, take it out of the ELB
   sudo elb-deregister-instances-from-lb MyLoadBalancer --instances i-4e05f721  --aws-credential-file=/var/keys/aws_credential_file
7. And after completing the server upgrade take it back in.
   sudo elb-register-instances-with-lb MyLoadBalancer --instances i-4e05f721  --aws-credential-file=/var/keys/aws_credential_file

Bottom Line

A simple process and careful design will keep you system up and running.

Keep Performing,

Moshe Kaplan