Sample ElasticBeanstalk Config for Rails 3 on Puma and Using a bundle / gems cached on s3 for faster scaling.

README.md

Quick / Cached Bundles on ElasticBeanstalk

Bonus, support Rack 1.4.5 with puma for Rails 3 apps

Basically we bundle install on one box, upload the result to a dedicated s3 bucked and then other servers/nodes can download the gems and save a ton of time compiling them.

I can not stress enough how the bucked should be dedicated as it will often remove all the files in the bucket to clear the cache / do a new gem build each month incase changes are made to backing ami / software, you can adjust the prefix to clear the bundle "cache key" more frequently by appending more date modifiers such as day or hour if you run into issues.

Note: You can remove 14downgradepuma if your app runs on Rails 4

ruby.conf

option_settings:
  - option_name: BUNDLE_DISABLE_SHARED_GEMS
    value: "true"
  - option_name: BUNDLE_PATH
    value: "vendor/bundle"
  - option_name: RAILS_SKIP_ASSET_COMPILATION
    value: "true"
  - option_name: RAILS_SKIP_MIGRATIONS
    value: "false"

packages:
  yum:
    git: []
    ImageMagick: []
    ImageMagick-devel: []
    libmemcached: []
    libmemcached-devel: []
    gcc: [] 
    libstdc++-devel: []
    gcc-c++: [] 
    libcurl-devel: []
    libxml2-devel: []
    openssl-devel: [] 
    mailcap: []
    make: []


files:
  "/opt/elasticbeanstalk/hooks/appdeploy/pre/10_bundle_install.sh":
    mode: "000700"
    owner: root
    group: root
    content: |
      #!/bin/bash
      # Do nothing

  "/opt/quick_bundle":
    mode: "000700"
    owner: root
    group: root
    content: |
      #!/bin/bash
      echo "==================$(date -u)===================="
      bundle_path="/var/app/shared"
      prefix="`date +%Y%m`"
      awscmd="aws"
      gem_s3_bucket="DEDICATED-S3-BUCKET-FOR-GEMS"
      makebundle="/usr/local/bin/bundle install --gemfile $EB_CONFIG_APP_ONDECK/Gemfile --path $bundle_path/bundle --without $BUNDLE_WITHOUT --deployment"
      existing="$awscmd s3 ls s3://$gem_s3_bucket"
      echo $existing
      existing=`$existing | grep -i $prefix-bundle.tar.gz`
      
      if [ -z "$existing" ];
      then
        echo "Gem file does not exist"
        # Remove all old packages
        $awscmd s3 rm s3://$gem_s3_bucket/ --recursive
        # Do some tar thing
        # Run bundle
        $makebundle
        chown webapp:webapp -R $bundle_path
        cd $bundle_path
        tar -zcvf $prefix-bundle.tar.gz bundle
        md5 -q $prefix-bundle.tar.gz >> /tmp/bundle-checksum
        $awscmd s3 cp $prefix-bundle.tar.gz s3://$gem_s3_bucket/
        $awscmd s3 cp /tmp/bundle-checksum s3://$gem_s3_bucket/
        rm $prefix-bundle.tar.gz
        rm /tmp/bundle-checksum
        echo "Bundle uploaded"
      else
        echo "Gem file exists"
        # Download existing package
        # Check md5 of downloader tar gz to make sure we're not intransit
        # Do 3 tries for consistency
        for i in `seq 1 3`;
        do
          $awscmd s3 cp s3://$gem_s3_bucket/$prefix-bundle.tar.gz $bundle_path/bundle.tar.gz
          $awscmd s3 cp s3://$gem_s3_bucket/bundle-checksum /tmp/bundle-checksum
          md5_fingerprint=`cat /tmp/bundle-checksum`
          my_md5=`md5 -q $bundle_path/bundle.tar.gz`
          if [ "$md5_fingerprint"="$my_md5" ];
          then
            echo "MD5 matched!!!!"
            cd $bundle_path
            tar zxvf $bundle_path/bundle.tar.gz
            rm $bundle_path/bundle.tar.gz
            rm /tmp/bundle-checksum
            $makebundle
            chown webapp:webapp -R $bundle_path
            exit 0;
          else
            echo "MD5 mismatch, wait 30 seconds."
            sleep 30
          fi
        done

        rm $bundle_path/bundle.tar.gz
        rm /tmp/bundle-checksum
        puts "Could not match md5 just bundle locally"
        $makebundle
        chown webapp:webapp -R $bundle_path
      fi
      

container_commands:
  06setuptemp:
    command: mkdir -p $EB_CONFIG_APP_ONDECK/tmp
    
  08removebundle:
    command: rm -rf $EB_CONFIG_APP_ONDECK/vendor/bundle; return true;
    ignoreErrors: true

  09makebundle:
    command: mkdir -p $EB_CONFIG_APP_ONDECK/vendor/bundle
    ignoreErrors: true

  10symlinkbundle:
    command: mkdir -p /var/app/shared/bundle; chown webapp:webapp -R /var/app/shared; ln -s /var/app/shared/bundle $EB_CONFIG_APP_ONDECK/vendor/bundle

  11bundleinstall:
    command: /bin/bash -l -c '/opt/quick_bundle' >> /var/log/quickbundle.log

  12fixperm:
    command: chown webapp:webapp -R /var/app/shared

  13fixperm2:
    command: chown webapp:webapp -R $EB_CONFIG_APP_ONDECK

  14downgradepuma:
    command: yes | gem uninstall puma; gem install puma --version 2.6.0 --no-ri --no-rdoc; gem install rack --version 1.4.5 --no-ri --no-rdoc; yes | gem uninstall rack --version 1.5.2; killall -9 puma
    ignoreErrors: true
    
command:
  14trymigrate:
    command: /var/app/shared/bundle exec rake db:migrate