AWS ElasticBeanstalk with custom AMI

Question

I have the following doubts about using custom AMI with AWS EB.

Now I have:

1. a default platform, Python 3.6 + Amazon Linux 1.10.0, and in EB configurations > Instances > AMI I get an ID that I think is the default AMI provided by AWS to launch the platform (and if it is like that than it should get modified at every platform update).
2. some platform configurations done with .ebextensions files
3. my Flask app that I deploy from CLI (eb deploy)

So, in order to avoid the .ebextensions configurations time, I'd like to use a custom AMI that includes (1) + (2) and continue to deploy my Flask app like before.

So to build the AMI:

• can I stop an EC2 instance of my running env and make an AMI from that one from EC2 console? If I do so, then the AMI would contain even my .ebextensions files and my app, is it a problem?
• if the AMI shouldn't include .ebextensions files, then the only way to custom the platform before doing the AMI is to SSH?
• after having built the AMI I put its ID in EB console > configurations > instances and then EB takes care of everything, like updating the AMI id in EC2 > autoscaling > launch options?
• to do a platofrm update I have first to manually rebuild the AMI starting from the new platform and then update the AMI ID in EB configurations? So it's not possible to update the platform from EB console like I was used to do before and then to save the new AMI?
• when I deploy my app it then shouldn't contain .ebextensions files?
• if I create the AMI with my app included, then EB autoscaling would even save the time of deploying the app? (Of course in this case to deploy I would have to create a new AMI first).

Thanks for help.

Answer 1

You can create Custom AMI of EC2 instance which is running for Elastic beanstalk. IF you are going with custom AMI then no need to use .ebextension files because either AMI should include all the changes which has already done when you deployed application along with ebextension file or do the necessary changes in server before creating AMI. But it is good to use default AMI which AWS provides while creation of Elastic Beanstalk and use .ebextension files to do required tasks during deployment.

Answer 2

can I stop an EC2 instance of my running env and make an AMI from that one from EC2 console? If I do so, then the AMI would contain even my .ebextensions files and my app, is it a problem?

You don't have to stop it. You can make AMI from running instance. Also your instance its in ASG, so stopping it is not a good idea.

if the AMI shouldn't include .ebextensions files, then the only way to custom the platform before doing the AMI is to SSH?

It shoudn't matter if you have pre-existing app on the ami. New deployment will install your app anyway.

after having built the AMI I put its ID in EB console > configurations > instances and then EB takes care of everything, like updating the AMI id in EC2 > autoscaling > launch options?

Yes,

to do a platofrm update I have first to manually rebuild the AMI starting from the new platform and then update the AMI ID in EB configurations? So it's not possible to update the platform from EB console like I was used to do before and then to save the new AMI?

Probably, have to repeat the process.

when I deploy my app it then shouldn't contain .ebextensions files?

It depends what they do. If they install software which is already on the custom ami, you can remove it.

if I create the AMI with my app included, then EB autoscaling would even save the time of deploying the app? (Of course in this case to deploy I would have to create a new AMI first).

The purpose of the custom ami is to save time on installing and configuring custom software that is normally not on the AWS amis. Its not to replace or elimiate the need of deploying your APP. You still need to do it, but can skip installing custom packages.

Answer 3

You can create a custom AMI from a running EC2 instance from the console, and from the CLI. Any AMI you create is a faithful copy of the instance, so if the instance has ebextensions, then the AMI will do also.

I think I understand that you want to create an AMI from instances being managed by ElasticBeanstalk? If that is so, then there are certain files that need to exist on the ElasticBeanstalk EC2 instance so that ElasticBeanstalk and Cloudformation can manage the environment. The .ebextensions are scripts are used to configure the environment, at least in my experience there are maintained in your repo. If your AMI has .ebextensions then they are most likely needed.

I don't think it is typical to use a custom AMI under ElasticBeanstalk: the whole point is to let AWS manage that layer for you. I would recommend that if you really need a custom AMI, you look at doing what you want to do directly in EC2 and forgo ElasticBeanstalk. ElasticBeanstalk is really only an abstracted 'friendly' interface to EC2 and other services (eg autoscaling and load balancer are actually EC2). Maybe even consider putting your application into a docker?