Tim Fulmer Tim Fulmer - 29 days ago 11
Node.js Question

How do I run `npm update -g npm` on Elastic Beanstalk?

How can I run

npm update -g npm
on my Elastic Beanstalk instances as they spin up? It's fairly easy to shell into each instance to run the update command manually, but this won't work through a scaling event, as more instances are added automatically.

How can i get the latest version of NPM on Elastic Beanstalk instances, in a way that works through an auto-scaling event?


It turns out this one is tricky, took a bit of digging and experimentation.

First, a quick bit about Elastic Beanstalk's lifecycle. There are several steps taken by AWS scripts running on each instance on deploy. For a Node.JS server, there are two of interest:

  • Install Node.JS
  • Run npm install

Installing Node.JS is where we can step in and do some magic. Most errors prompting the desire to do magic, or other things, to a beanstalk instance come from the npm install step.

Getting back on topic, the script AWS used to install node on beanstalk instances is /opt/elasticbeanstalk/hooks/appdeploy/pre/40install_node.sh. It usually looks like this:


set -xe

/opt/elasticbeanstalk/containerfiles/ebnode.py --action node-install

This script installs a bunch of different node versions to /opt/elasticbeanstalk/node-install, including the one selected in the beanstalk configuration. Wouldn't it be nice to run npm update -g npm with one of the node versions sitting in that folder?

It turns out beanstalk supplies a mechanism to swap out files on each instance during deploy. Basically you configure YAML files in a .ebextensions folder in your app. There are two ways to reference the file contents, in line, or in an s3 bucket. I use the s3 bucket approach, giving a node.config YAML looking like this:

  "/opt/elasticbeanstalk/hooks/appdeploy/pre/40install_node.sh" :
    mode: "000775"
    owner: root
    group: users
    source: https://s3.amazonaws.com/bucketname/40install_node.sh
    authentication: S3Access
          type: S3
          roleName: aws-elasticbeanstalk-ec2-role
          buckets: bucketname

Note the S3Access property. We keep the bucket private, granting access to the aws-elasticbeanstalk-ec2-role using IAM.

Now all we need is a version of 40install_node.sh running the npm update:


set -xe

/opt/elasticbeanstalk/containerfiles/ebnode.py --action node-install

# Update npm
cd /opt/elasticbeanstalk/node-install/node-v0.12.2-linux-x64/bin/ && /opt/elasticbeanstalk/node-install/node-v0.12.2-linux-x64/bin/npm update npm -g

You can put any customization of your node install in this file as well. Just remember to keep an eye on the path to node, it will change as node versions go up in the beanstalk configuration.