avoid rebuilding node_modules in elastic beanstalk

Question

We have a fairly simple node.js app, but due to AWS Elastic Beanstalk deployment mechanism, it takes about 5 minutes to roll-out a new version (via git aws.push) even after a single file commit.

I.e. the commit itself (and upload) is fast (only 1 file to push), but then Elastic Beanstalk fetches whole package from S3, unzips it and runs npm install, which causes node-gyp to compile some modules. Upon installation/building completion, Elastic Beanstalk wipes /var/app/current and replaces it with the new app version.

Needless to say, constant node_modules rebuilding is not necessary, and rebuilding that takes 30 seconds on my old Macbook Air, takes >5 mins on a ec2.micro instance, not fun.

I see two approaches here:

1. tweak /opt/containerfiles/ebnode.py and play with node_modules location to avoid its removal and rebuilding upon deployment.
2. set up a git repo on Elastic Beanstalk EC2 instance and basically re-write deployment procedure ourselves, so /var/app/current receives pushes and runs npm install only when necessary (which makes Elastic Beanstalk to look like OpsWorks..)

Both options lack grace and are prone to issues when Amazon updates their Elastic Beanstalk hooks and architecture.

Maybe somebody has a better idea how to avoid constant rebuilding of node_modules that are already present in the app dir? Thank you.

Answer 1

Thanks Kirill, it was really helpful !

I'm just sharing my config file for people who just look the simple solution to the npm install. This file needs to be placed in the .ebextensions folder of the project, it is lighter since it doesn't include last version of node installation, and ready to use.

It also dynamically checks the node version installed, so no need for it to be included in the env.vars file.

.ebextensions/00_deploy_npm.config

files:
  "/opt/elasticbeanstalk/env.vars" :
    mode: "000775"
    owner: root
    group: users
    content: |
      export NPM_CONFIG_LOGLEVEL=error
      export NODE_PATH=`ls -td /opt/elasticbeanstalk/node-install/node-* | head -1`/bin
  "/opt/elasticbeanstalk/hooks/appdeploy/pre/50npm.sh" :
    mode: "000775"
    owner: root
    group: users
    content: |
      #!/bin/bash
      . /opt/elasticbeanstalk/env.vars
      function error_exit
      {
        eventHelper.py --msg "$1" --severity ERROR
        exit $2
      }

      #install not-installed yet app node_modules
      if [ ! -d "/var/node_modules" ]; then
        mkdir /var/node_modules ;
      fi
      if [ -d /tmp/deployment/application ]; then
        ln -s /var/node_modules /tmp/deployment/application/
      fi

      OUT=$([ -d "/tmp/deployment/application" ] && cd /tmp/deployment/application && $NODE_PATH/npm install 2>&1) || error_exit "Failed to run npm install.  $OUT" $?
      echo $OUT
  "/opt/elasticbeanstalk/hooks/configdeploy/pre/50npm.sh" :
    mode: "000666"
    owner: root
    group: users
    content: |
       #no need to run npm install during configdeploy

Answer 2

25/01/13 NOTE: updated scripts to run npm -g version upgrade (only once, on initial instance roll out or rebuild) and to avoid NPM operations during EB configuration change (when app dir is not present, to avoid error and to speed up configuration updates).

Okay, Elastic Beanstalk behaves dodgy with recent node.js builds (including presumably supported v.0.10.10), so I decided to go ahead and tweak EB to do the following:

1. to install ANY node.js version as per your env.config (including the most recent ones that are not yet supported by AWS EB)
2. to avoid rebuilding existing node modules, including in-app node_modules dir
3. to install node.js globally (and any desired module as well).

Basically, I use env.config to replace deploy&config hooks with customized ones (see below). Also, in a default EB container setup some env variables are missing ($HOME for example) and node-gyp sometimes fails during rebuild because of it (took me 2 hours of googling and reinstalling libxmljs to resolve this).

Below are the files to be included along with your build. You can inject them via env.config as inline code or via source: URL (as in this example)

env.vars (desired node version & arch are included here and in env.config, see below)

export HOME=/root
export NPM_CONFIG_LOGLEVEL=error
export NODE_VER=0.10.24
export ARCH=x86
export PATH="$PATH:/opt/elasticbeanstalk/node-install/node-v$NODE_VER-linux-$ARCH/bin/:/root/.npm"

40install_node.sh (fetch and ungzip desired node.js version, make global symlinks, update global npm version)

#!/bin/bash
#source env variables including node version
. /opt/elasticbeanstalk/env.vars

function error_exit
{
  eventHelper.py --msg "$1" --severity ERROR
  exit $2
}

#UNCOMMENT to update npm, otherwise will be updated on instance init or rebuild
#rm -f /opt/elasticbeanstalk/node-install/npm_updated

#download and extract desired node.js version
OUT=$( [ ! -d "/opt/elasticbeanstalk/node-install" ] && mkdir /opt/elasticbeanstalk/node-install ; cd /opt/elasticbeanstalk/node-install/ && wget -nc http://nodejs.org/dist/v$NODE_VER/node-v$NODE_VER-linux-$ARCH.tar.gz && tar --skip-old-files -xzpf node-v$NODE_VER-linux-$ARCH.tar.gz) || error_exit "Failed to UPDATE node version. $OUT" $?.
echo $OUT

#make sure node binaries can be found globally
if [ ! -L /usr/bin/node ]; then
  ln -s /opt/elasticbeanstalk/node-install/node-v$NODE_VER-linux-$ARCH/bin/node /usr/bin/node
fi

if [ ! -L /usr/bin/npm ]; then
ln -s /opt/elasticbeanstalk/node-install/node-v$NODE_VER-linux-$ARCH/bin/npm /usr/bin/npm
fi

if [ ! -f "/opt/elasticbeanstalk/node-install/npm_updated" ]; then
/opt/elasticbeanstalk/node-install/node-v$NODE_VER-linux-$ARCH/bin/ && /opt/elasticbeanstalk/node-install/node-v$NODE_VER-linux-$ARCH/bin/npm update npm -g
touch /opt/elasticbeanstalk/node-install/npm_updated
echo "YAY! Updated global NPM version to `npm -v`"
else
  echo "Skipping NPM -g version update. To update, please uncomment 40install_node.sh:12"
fi

50npm.sh (creates /var/node_modules, symlinks it to app dir and runs npm install. You can install any module globally from here, they will land in /root/.npm)

#!/bin/bash
. /opt/elasticbeanstalk/env.vars
function error_exit
{
  eventHelper.py --msg "$1" --severity ERROR
  exit $2
}

#install not-installed yet app node_modules
if [ ! -d "/var/node_modules" ]; then
  mkdir /var/node_modules ;
fi
if [ -d /tmp/deployment/application ]; then
  ln -s /var/node_modules /tmp/deployment/application/
fi

OUT=$([ -d "/tmp/deployment/application" ] && cd /tmp/deployment/application && /opt/elasticbeanstalk/node-install/node-v$NODE_VER-linux-$ARCH/bin/npm install 2>&1) || error_exit "Failed to run npm install.  $OUT" $?
echo $OUT

env.config (note node version here too, and to be safe, put desired node version in env config in AWS console as well. I'm not certain which of these settings will take precedence.)

packages:
  yum:
    git: []
    gcc: []
    make: []
    openssl-devel: []

option_settings:
  - option_name: NODE_ENV
    value: production
  - option_name: RDS_HOSTNAME
    value: fill_me_in
  - option_name: RDS_PASSWORD
    value: fill_me_in
  - option_name: RDS_USERNAME
    value: fill_me_in
  - namespace: aws:elasticbeanstalk:container:nodejs
    option_name: NodeVersion
    value: 0.10.24

files:
  "/opt/elasticbeanstalk/env.vars" :
    mode: "000775"
    owner: root
    group: users
    source: https://dl.dropbox.com/....
  "/opt/elasticbeanstalk/hooks/configdeploy/pre/40install_node.sh" :
    mode: "000775"
    owner: root
    group: users
    source: https://raw.github.com/....
  "/opt/elasticbeanstalk/hooks/appdeploy/pre/50npm.sh" :
    mode: "000775"
    owner: root
    group: users
    source: https://raw.github.com/....
  "/opt/elasticbeanstalk/hooks/configdeploy/pre/50npm.sh" :
    mode: "000666"
    owner: root
    group: users
    content: |
       #no need to run npm install during configdeploy
  "/opt/elasticbeanstalk/hooks/appdeploy/pre/40install_node.sh" :
    mode: "000775"
    owner: root
    group: users
    source: https://raw.github.com/....

There you have it: on t1.micro instance deployment now takes 20-30 secs instead of 10-15 minutes! If you deploy 10 times a day, this tweak will save you 3 (three) weeks in a year. Hope it helps and special thanks to AWS EB staff for my lost weekend :)