将 Rails 部署到 Elastic Beanstalk、nodejs？

Question

I want to host my app on a VPC EC2 instance with AWS, and this line in the documentation has me somewhat confused:

Install nodejs to allow the Rails server to run locally:

$ sudo apt-get install nodejs

I was just wondering why I need nodejs at all, let alone to allow the rails server to run locally since i thought that this was already handled by WEBrick.

Heres a link to the documentation in question:

http://docs.aws.amazon.com/elasticbeanstalk/latest/dg/create_deploy_Ruby_rails.html

Answer 1

Rails uses a Javascript runtime for certain tasks (generating scaffolds and compiling templates among others). You do not need to use nodejs, you can add other runtimes as gems in your Gemfile, eg therubyracer , therubyrhino . (YMMV on EC2, if it suggests using nodejs, I would install it unless you have a good reason not to)

Answer 2

The title of the question is unclear. Elasticbeanstalk uses EC2 instances but you should never ssh directly into an EC2 server to make changes.

Elasticbeanstalk will destroy and create EC2 instances to scale with the web traffic coming to the application. Making changes to one particular instance will not guarantee it will make the changes for all of the EC2 instances belonging to one Elasticbeanstalk application.

Also that particular instance can be destroyed when deploying, or rebuilding or when the app scales back down.

If you're using the Ruby platform on Elasticbeanstalk you'll need to use their builtin in EB extensions to either run a command to install node or use the yum package manager to install it.

Here's documentation that describes the yum method:

https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/customize-containers-ec2.html#linux-packages