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Alternate Capistrano strategy that stores the package on S3 for later auto-scaling use.
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README.md

Capistrano::S3::Copy

This is a revised implementation of the ideas in Bill Kirtleys capistrano-s3 gem.

I have a requirement to push new deployments via capistrano, but also to retain the last deployed package in S3 for the purposes of auto-scaling.

This gem use Capistrano's own code to package the tarball, but instead of deploying it to each machine, we deploy it to a configured S3 bucket (using s3cmd provided by the https://github.com/s3tools/s3cmd), then deploy it from there to the known nodes from the capistrano script.

Installation

Add these line to your application's Gemfile:

group :development do
  gem 'capstrano-s3-copy'
end  

And then execute:

$ bundle

Or install it yourself as:

$ gem install capistrano-s3-copy

Usage

In your deploy.rb file, we need to tell Capistrano to adopt our new strategy:

set :deploy_via, :s3_copy

Then we need to provide AWS account details to authorize the upload/download of our package to S3

set :aws_access_key_id,     ENV['AWS_ACCESS_KEY_ID']
set :aws_secret_access_key, ENV['AWS_SECRET_ACCESS_KEY']

Finally, we need to indicate which bucket to store the packages in:

set :aws_releases_bucket, 'mybucket-deployments'

The package will be stored in S3 prefixed with a rails_env that was set in capistrano:

e.g.

S3://mybucket-deployment/production/201204212007.tar.gz

If the deployment succeeds, another file is written to S3:

S3://mybucket-deployment/production/aws_install.sh

The intention is that auto-scaled instances started after the deploy could download this well-known script to an AMI, and executing it would bring down the latest tarball, and extract it in a manner similar to someone running:

cap deploy:setup cap deploy

Of course, everyone has tweaks that they make to the standard capistrano recipe. For this reason, the script thats executed is generated from an ERB template.

#!/bin/sh

# Auto-scaling capistrano like deployment script Rails3 specific.

set -x
set -e

echo "AWS_ACCESS_KEY_ID=${AWS_ACCESS_KEY_ID}"
echo "AWS_SECRET_ACCESS_KEY=${AWS_SECRET_ACCESS_KEY}"

if [ "${AWS_ACCESS_KEY_ID}" == "" ]; then
  echo "Expecting the environment variable AWS_ACCESS_KEY_ID to be set"
  exit 1
fi

if [ "${AWS_SECRET_ACCESS_KEY}" == "" ]; then
  echo "Expecting the environment variable AWS_SECRET_ACCESS_KEY to be set"
  exit 2
fi

AWS_RELEASES_BUCKET=<%= configuration[:aws_releases_bucket] %>
RAILS_ENV=<%= configuration[:rails_env] %>              # e.g. production
DEPLOY_TO=<%= configuration[:deploy_to] %>              # e.g. /u/apps/myapp
RELEASES_PATH=<%= configuration[:releases_path] %>      # e.g. /u/apps/myapp/releases
RELEASE_PATH=<%= configuration[:release_path] %>        # e.g. /u/apps/myapp/releases/20120428210958
SHARED_PATH=<%= configuration[:shared_path] %>          # e.g. /u/apps/myapp/shared
CURRENT_PATH=<%= configuration[:current_path] %>        # e.g. /u/apps/myapp/current

PACKAGE_NAME=<%= File.basename(filename) %>             # e.g. 20120428210958.tar.gz
S3_PACKAGE_PATH=${RAILS_ENV}/${PACKAGE_NAME}            # e.g. production/20120428210958.tar.gz
DOWNLOADED_PACKAGE_PATH=<%= remote_filename %>          # e.g. /tmp/20120428210958.tar.gz
DECOMPRESS_CMD="<%= decompress(remote_filename).join(" ") %>" # e.g. tar xfz /tmp/20120428210958.tar.gz

mkdir -p $DEPLOY_TO
mkdir -p $RELEASES_PATH
mkdir -p ${SHARED_PATH}
mkdir -p ${SHARED_PATH}/system
mkdir -p ${SHARED_PATH}/log
mkdir -p ${SHARED_PATH}/pids

touch ${SHARED_PATH}/log/${RAILS_ENV}.log
chmod 0666 ${SHARED_PATH}/log/${RAILS_ENV}.log
chmod -R g+w ${DEPLOY_TO}

# AFTER: cap deploy:setup
# Project specific shared directories
# mkdir -p ${SHARED_PATH}/content
# mkdir -p ${SHARED_PATH}/uploads

# cap deploy:update_code
s3cmd get ${AWS_RELEASES_BUCKET}:${S3_PACKAGE_PATH} ${DOWNLOADED_PACKAGE_PATH} 2>&1
cd ${RELEASES_PATH} && ${DECOMPRESS_CMD} && rm ${DOWNLOADED_PACKAGE_PATH}

# cap deploy:assets_symlink   (Rails 3.x specific)
rm -rf ${RELEASE_PATH}/public/assets
mkdir -p ${RELEASE_PATH}/public
mkdir -p ${DEPLOY_TO}/shared/assets
ln -s ${SHARED_PATH}/assets ${RELEASE_PATH}/public/assets

# cap deploy:finalize_update
chmod -R g+w ${RELEASE_PATH}
rm -rf ${RELEASE_PATH}/log
rm -rf ${RELEASE_PATH}/public/system
rm -rf ${RELEASE_PATH}/tmp/pids
mkdir -p ${RELEASE_PATH}/public
mkdir -p ${RELEASE_PATH}/tmp
ln -s ${SHARED_PATH}/system ${RELEASE_PATH}/public/system
ln -s ${SHARED_PATH}/log ${RELEASE_PATH}/log
ln -s ${SHARED_PATH}/pids ${RELEASE_PATH}/tmp/pids

# AFTER: cap deploy:finalize_update
cd ${RELEASE_PATH}
bundle install --gemfile ${RELEASE_PATH}/Gemfile --path ${SHARED_PATH}/bundle --deployment --quiet --without development test

# AFTER: cap deploy:update_code
# cap deploy:assets:precompile
cd ${RELEASE_PATH}
bundle exec rake RAILS_ENV=${RAILS_ENV} RAILS_GROUPS=assets assets:precompile

# Project specific shared symlinking
#ln -nfs ${SHARED_PATH}/content ${RELEASE_PATH}/public/content
#ln -nfs ${SHARED_PATH}/uploads ${RELEASE_PATH}/public/uploads

# cap deploy:create_symlink
rm -f ${CURRENT_PATH}
ln -s ${RELEASE_PATH} ${CURRENT_PATH}

# cap deploy:restart
# touch ${CURRENT_PATH}/tmp/restart.txt

# AFTER: cap deploy:restart
# cd ${CURRENT_PATH};RAILS_ENV=${RAILS_ENV} script/delayed_job restart

An alternative ERB script can be configured via something like this:

set :aws_install_script, File.read(File.join(File.dirname(__FILE__), "custom_aws_install.sh.erb")

Contributing

  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Added some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request
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