Deploy Application via Chef

After creating the Ruby on Rails application mentioned in my blog, the next task was to deploy the application to a hosted web server.

The traditional way would be to write rake tasks and trigger them manually or using a CI build/deploy. Well chef provides another easy solution to deploy an application. The recipe below performs all the tasks of deploying an application. The before_migrate script contains the tasks that need to be performed before the application kicks in. The migration_command is the final command that is run to mark deployment successful. deploy_revision is used to make sure that the recipe would only be executed once the git head changes in the repository from the last deployed version. symlink_before_migrate can be used to create symlinks to the yml files used in the configuring the application.

The deploy cookbook for a basic app looks like below

app_user="user"

deploy_dir="/opt/application_deploy"

user  app_user

directory "/home/#{app_user}/.ssh" do

mode "0700"

owner app_user

group app_user

end


cookbook_file "/home/#{app_user}/.ssh/deploy" do

source "deploy"

mode "0600"

owner app_user

group app_user

end


cookbook_file"/home/#{app_user}/.ssh/config" do

source "ssh_config"

mode "0644"

owner app_user

group app_user

end


directory deploy_dir do

recursive true

owner app_user

group app_user

mode "755"

end


%w{config log}.each do |dir|

directory "#{deploy_dir}/shared/#{dir}" do

owner app_user

group app_user

mode "755"

recursive true

end

end


gem_package "bundler"


cookbook_file "#{deploy_dir}/shared/config/database.yml" do

source "database.yml"

mode "0644"

owner app_user

group app_user

end

deploy_revision deploy_dir do

repo "<Git hub repository ssh url>"

environment "production"

revision "HEAD"

user app_user

symlink_before_migrate "config/database.yml" => "config/database.yml"

migration_command "bundle exec rails server -d -e production"

migrate true

action :deploy

restart_command "touch tmp/restart.txt"

before_migrate do

execute "bundle install" do

command "bundle install --path .bundle"

cwd  "#{release_path}"

user app_user

end


execute "Create db" do

command 'bundle exec rake db:create RAILS_ENV="production" '

cwd "#{release_path}"

user app_user

end


execute "Migrate db" do

command 'bundle exec rake db:migrate RAILS_ENV="production"'

cwd  "#{release_path}"

user app_user

end

end

end

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