Deploying on EBS makes my app unavailable

Question

Worse, it shows a 502 Bad Gateway error that I haven't been able to customize into something more user-friendly.
I thought it would only happen on single instance apps, but even with a load balancer and 2 instances, it still happens.

And although I haven't tested it yet, I'm concerned the same problem could happen during vertical scaling operations.
Is there a way to configure the load balancer the deploy the instances in sequence and only deploy on the next instance after the first one is available again? (And route the traffic intelligently in the meantime)

I need to reduce down time to an absolute minimum, as our CICD process involves frequent deployments.
Thanks in advance :)

Accepted Answer

Hi,

You should try the Rolling Deployments available in Elastic BeansTalk: see https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/using-features.rolling-version-deploy.html#environments-cfg-rollingdeployments-method

```
When processing a batch, Elastic Beanstalk detaches all instances in the batch from 
the load balancer, deploys the new application version, and then reattaches the instances.
 If you enable connection draining, Elastic Beanstalk drains existing connections from the 
Amazon EC2 instances in each batch before beginning the deployment.
```

See all details following this intro to see all the options that you have to erase the downtime of you app.

Best

Didier

Deploying on EBS makes my app unavailable

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