Application cookbook

This cookbook is initially designed to be able to describe and deploy web applications. Currently supported:

• Rails
• Java
• Django

Other application stacks (PHP, etc) will be supported as new recipes at a later date.

This cookbook aims to provide primitives to install/deploy any kind of application driven entirely by data defined in an abstract way through a data bag.

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Requirements

Chef 0.8 or higher required.

The following Opscode cookbooks are dependencies:

• runit
• unicorn
• passenger_apache2
• tomcat
• python
• gunicorn

The following are also dependencies, though the recipes are considered deprecated, may be useful for future development.

• ruby_enterprise
• passenger_enterprise

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Recipes

The application cookbook contains the following recipes.

default

Searches the apps data bag and checks that a server role in the app exists on this node, adds the app to the run state and uses the role for the app to locate the recipes that need to be used. The recipes listed in the "type" part of the data bag are included by this recipe, so only the "application" recipe needs to be in the node or role run_list.

See below regarding the application data bag structure.

django

Using the node's run_state that contains the current application in the search, this recipe will:

• create an application specific virtualenv
• install required packages and pips
• set up the deployment scaffolding
• creates settings_local.py file with the database connection information if required
• performs a revision-based deploy

This recipe can be used on nodes that are going to run the application, or on nodes that need to have the application code checkout available such as supporting utility nodes or a configured load balancer that needs static assets stored in the application repository.

For pip requirements.txt files: ensure the requirements.txt file is present in the root of the application code (APP_ROOT/requirements.txt) or named after the node's current app_environment in a directory named requirements (requirements/production.txt) and pip install -r will be run before migrations.

In order to manage running database migrations (python manage.py migrate), you can use a role that sets the run_migrations attribute for the application (my_app, below) in the correct environment (production, below). Note the data bag item needs to have migrate set to true. See the data bag example below.

{
  "name": "my_app_run_migrations",
  "description": "Run db:migrate on demand for my_app",
  "json_class": "Chef::Role",
  "default_attributes": {
  },
  "override_attributes": {
    "apps": {
      "my_app": {
        "production": {
          "run_migrations": true
        }
      }
    }
  },
  "chef_type": "role",
  "run_list": [
  ]
}

Simply apply this role to the node's run list when it is time to run migrations, and the recipe will remove the role when done. Since Django does not have a standard database migration function built into the core framework, we assume the popular South framework is being used.

gunicorn

Requires gunicorn cookbook.

Gunicorn is installed, default attributes are set for the node and an app specific gunicorn config and runit service are created.

java_webapp

Using the node's run_state that contains the current application in the search, this recipe will:

• install required packages
• set up the deployment scaffolding
• create the context configuration for the servlet container
• performs a remote_file deploy.

The servlet container context configuration (context.xml) exposes the following JNDI resources which can be referenced by the webapp's deployment descriptor (web.xml):

• A JDBC datasource for all databases in the node's current app_environment. The datasource uses the information (including JDBC driver) specified in the data bag item for the application.
• An Environment entry that matches the node's current app_environment attribute value. This is useful for loading environment specific properties files in the web application.

This recipe assumes some sort of build process, such as Maven or a Continuous Integration server like Hudson, will create a deployable artifact and make it available for download via HTTP (such as S3 or artifactory).

passenger_apache2

Requires apache2 and passenger_apache2 cookbooks. The recipe[apache2] entry should come before recipe[application] in the run list.

"run_list": [
  "recipe[apache2]",
  "recipe[application]"
],

Sets up a passenger vhost template for the application using the apache2 cookbook's web_app definition. Use this with the rails recipe, in the list of recipes for a specific application type. See data bag example below.

rails

Using the node's run_state that contains the current application in the search, this recipe will:

• install required packages and gems
• set up the deployment scaffolding
• creates database and memcached configurations if required
• performs a revision-based deploy.

This recipe can be used on nodes that are going to run the application, or on nodes that need to have the application code checkout available such as supporting utility nodes or a configured load balancer that needs static assets stored in the application repository.

For Gem Bundler: include bundler or bundler08 in the gems list. bundle install or gem bundle will be run before migrations. The bundle install command is invoked with the --deployment and --without flags following Bundler best practices.

For config.gem in environment: rake gems:install RAILS_ENV=<node environment> will be run when a Gem Bundler command is not.

In order to manage running database migrations (rake db:migrate), you can use a role that sets the run_migrations attribute for the application (my_app, below) in the correct environment (production, below). Note the data bag item needs to have migrate set to true. See the data bag example below.

{
  "name": "my_app_run_migrations",
  "description": "Run db:migrate on demand for my_app",
  "json_class": "Chef::Role",
  "default_attributes": {
  },
  "override_attributes": {
    "apps": {
      "my_app": {
        "production": {
          "run_migrations": true
        }
      }
    }
  },
  "chef_type": "role",
  "run_list": [
  ]
}

Simply apply this role to the node's run list when it is time to run migrations, and the recipe will remove the role when done.

tomcat

Requires tomcat cookbook.

Tomcat is installed, default attributes are set for the node and the app specific context.xml is symlinked over to Tomcat's context directory as the root context (ROOT.xml).

unicorn

Requires unicorn cookbook.

Unicorn is installed, default attributes are set for the node and an app specific unicorn config and runit service are created.

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Deprecated Recipes

The following recipes are deprecated and have been removed from the cookbook. To retrieve an older version, reference commit 4396ce6.

passenger-nginx
rails_nginx_ree_passenger

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Application Data Bag

The applications data bag expects certain values in order to configure parts of the recipe. Below is a paste of the JSON, where the value is a description of the key. Use your own values, as required. Note that this data bag is also used by the database cookbook, so it will contain database information as well. Items that may be ambiguous have an example.

The application used in examples is named my_app and the environment is production. Most top-level keys are Arrays, and each top-level key has an entry that describes what it is for, followed by the example entries. Entries that are hashes themselves will have the description in the value.

Note about "type": the recipes listed in the "type" will be included in the run list via include_recipe in the application default recipe based on the type matching one of the server_roles values.

Note about packages, the version is optional. If specified, the version will be passed as a parameter to the resource. Otherwise it will use the latest available version per the default :install action for the package provider.

Rail's version additional notes

Note about databases, the data specified will be rendered as the database.yml file. In the database cookbook, this information is also used to set up privileges for the application user, and create the databases.

Note about gems, the version is optional. If specified, the version will be passed as a parameter to the resource. Otherwise it will use the latest available version per the default :install action for the package provider.

An example is data bag item is included in this cookbook at examples/data_bags/apps/rails_app.json.

Java webapp version additional notes

Note about databases, the data specified will be rendered as JNDI Datasource Resources in the servlet container context confiruation (context.xml) file. In the database cookbook, this information is also used to set up privileges for the application user, and create the databases.

An example is data bag item is included in this cookbook at examples/data_bags/apps/java_app.json.

Django version additional notes

Note about databases, the data specified will be rendered as the settings_local.py file. In the database cookbook, this information is also used to set up privileges for the application user, and create the databases.

Note about pips, the version is optional. If specified, the version will be passed as a parameter to the resource. Otherwise it will use the latest available version per the default :install action for the python_pip package provider.

The local_settings_file_name value may be used to supply an alternate name for the environment specific settings_local.py, since Django projects do not have a standard name for this file.

An example is data bag item is included in this cookbook at examples/data_bags/apps/django_app.json.

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Usage

To use the application cookbook, we recommend creating a role named after the application, e.g. my_app. This role should match one of the server_roles entries, that will correspond to a type entry, in the databag. Create a Ruby DSL role in your chef-repo, or create the role directly with knife.

% knife role show my_app
{
  "name": "my_app",
  "chef_type": "role",
  "json_class": "Chef::Role",
  "default_attributes": {
  },
  "description": "",
  "run_list": [
    "recipe[application]"
  ],
  "override_attributes": {
  }
}

Also recommended is a cookbook named after the application, e.g. my_app, for additional application specific setup such as other config files for queues, search engines and other components of your application. The my_app recipe can be used in the run list of the role, if it includes the application recipe.

You should also have a role for the environment(s) you wish to use this cookbook. Similar to the role above, create the Ruby DSL file in chef-repo, or create with knife directly.

% knife role show production
{
  "name": "production",
  "chef_type": "role",
  "json_class": "Chef::Role",
  "default_attributes": {
    "app_environment": "production"
  },
  "description": "production environment role",
  "run_list": [

  ],
  "override_attributes": {
  }
}

This role uses a default attribute so nodes can be moved into other environments on the fly simply by modifying their node object directly on the Chef Server.

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License and Author

Author:: Adam Jacob (adam@opscode.com)
Author:: Joshua Timberman (joshua@opscode.com)
Author:: Seth Chisamore (schisamo@opscode.com)

Copyright 2009-2011, Opscode, Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.