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AWS OpsWorks
User Guide (API Version 2013-02-18)

Setup Recipes

Setup recipes are assigned to the layer's Setup lifecycle event and run after an instance boots. They perform tasks such as installing packages, creating configuration files, and starting services. After the Setup recipes finish running, AWS OpsWorks Stacks runs the Deploy recipes to deploy any apps to the new instance.

tomcat::setup

The tomcat::setup recipe is intended to be assigned to a layer's Setup lifecycle event.

include_recipe 'tomcat::install' include_recipe 'tomcat::service' service 'tomcat' do action :enable end # for EBS-backed instances we rely on autofs bash '(re-)start autofs earlier' do user 'root' code <<-EOC service autofs restart EOC notifies :restart, resources(:service => 'tomcat') end include_recipe 'tomcat::container_config' include_recipe 'apache2' include_recipe 'tomcat::apache_tomcat_bind'

tomcat::setup recipe is largely a metarecipe. It includes a set of dependent recipes that handle most of the details of installing and configuring Tomcat and related packages. The first part of tomcat::setup runs the following recipes, which are discussed later:

The middle part of tomcat::setup enables and starts the Tomcat service:

  • The Chef service resource enables the Tomcat service at boot.

  • The Chef bash resource runs a Bash script to start the autofs daemon, which is necessary for Amazon EBS-backed instances. The resource then notifies the service resource to restart the Tomcat service.

    For more information, see: autofs (for Amazon Linux) or Autofs (for Ubuntu).

The final part of tomcat::setup creates configuration files and installs and configures the front-end Apache server:

  • The tomcat::container_config recipe creates configuration files.

  • The apache2 recipe (which is shorthand for apache2::default) is an AWS OpsWorks Stacks built-in recipe that installs and configures an Apache server.

  • The tomcat::apache_tomcat_bind recipe configures the Apache server to function as a front-end for the Tomcat server.

Note

You can often save time and effort by using built-in recipes to perform some of the required tasks. This recipe uses the built in apache2::default recipe to install Apache rather than implementing it from scratch. For another example of how to use built-in recipes, see Deploy Recipes.

The following sections describe the Tomcat cookbook's Setup recipes in more detail. For more information on the apache2 recipes, see opsworks-cookbooks/apache2.

tomcat::install

The tomcat::install recipe installs the Tomcat server, the OpenJDK, and a Java connector library that handles the connection to the MySQL server.

tomcat_pkgs = value_for_platform( ['debian', 'ubuntu'] => { 'default' => ["tomcat#{node['tomcat']['base_version']}", 'libtcnative-1', 'libmysql-java'] }, ['centos', 'redhat', 'fedora', 'amazon'] => { 'default' => ["tomcat#{node['tomcat']['base_version']}", 'tomcat-native', 'mysql-connector-java'] }, 'default' => ["tomcat#{node['tomcat']['base_version']}"] ) tomcat_pkgs.each do |pkg| package pkg do action :install end end link ::File.join(node['tomcat']['lib_dir'], node['tomcat']['mysql_connector_jar']) do to ::File.join(node['tomcat']['java_dir'], node['tomcat']['mysql_connector_jar']) action :create end # remove the ROOT webapp, if it got installed by default include_recipe 'tomcat::remove_root_webapp'

The recipe performs the following tasks:

  1. Creates a list of packages to be installed, depending on the instance's operating system.

  2. Installs each package in the list.

    The Chef package resource uses the appropriate provider—yum for Amazon Linux and apt-get for Ubuntu— to handle the installation. The package providers install OpenJDK as a Tomcat dependency, but the MySQL connector library must be installed explicitly.

  3. Uses a Chef link resource to create a symlink in the Tomcat server's lib directory to the MySQL connector library in the JDK.

    Using the default attribute values, the Tomcat lib directory is /usr/share/tomcat6/lib and the MySQL connector library (mysql-connector-java.jar) is in /usr/share/java/.

The tomcat::remove_root_webapp recipe removes the ROOT web application (/var/lib/tomcat6/webapps/ROOT by default) to avoid some security issues.

ruby_block 'remove the ROOT webapp' do block do ::FileUtils.rm_rf(::File.join(node['tomcat']['webapps_base_dir'], 'ROOT'), :secure => true) end only_if { ::File.exists?(::File.join(node['tomcat']['webapps_base_dir'], 'ROOT')) && !::File.symlink?(::File.join(node['tomcat']['webapps_base_dir'], 'ROOT')) } end

The only_if statement ensures that the recipe removes the file only if it exists.

Note

The Tomcat version is specified by the ['tomcat']['base_version'] attribute, which is set to 6 in the attributes file. To install Tomcat 7, you can use custom JSON attributes to override the attribute. Just edit your stack settings and enter the following JSON in the Custom Chef JSON box, or add it to any existing custom JSON:

{ 'tomcat' : { 'base_version' : 7 } }

The custom JSON attribute overrides the default attribute and sets the Tomcat version to 7. For more information on overriding attributes, see Overriding Attributes.

tomcat::service

The tomcat::service recipe creates the Tomcat service definition.

service 'tomcat' do service_name "tomcat#{node['tomcat']['base_version']}" case node[:platform] when 'centos', 'redhat', 'fedora', 'amazon' supports :restart => true, :reload => true, :status => true when 'debian', 'ubuntu' supports :restart => true, :reload => false, :status => true end action :nothing end

The recipe uses the Chef service resource to specify the Tomcat service name (tomcat6, by default) and sets the supports attribute to define how Chef manages the service's restart, reload, and status commands on the different operating systems.

  • true indicates that Chef can use the init script or other service provider to run the command

  • false indicates that Chef must attempt to run the command by other means.

Notice that the action is set to :nothing. For each lifecycle event, AWS OpsWorks Stacks initiates a Chef run to execute the appropriate set of recipes. The Tomcat cookbook follows a common pattern of having a recipe create the service definition, but not restart the service. Other recipes in the Chef run handle the restart, typically by including a notifies command in the template resources that are used to create configuration files. Notifications are a convenient way to restart a service because they do so only if the configuration has changed. In addition, if a Chef run has multiple restart notifications for a service, Chef restarts the service at most once. This practice avoids problems that can occur when attempting to restart a service that is not fully operational, which is a common source of Tomcat errors.

The Tomcat service must be defined for any Chef run that uses restart notifications. tomcat::service is therefore included in several recipes, to ensure that the service is defined for every Chef run. There is no penalty if a Chef run includes multiple instances of tomcat::service because Chef ensures that a recipe executes only once per run, regardless of how many times it is included.

tomcat::container_config

The tomcat::container_config recipe creates configuration files from cookbook template files.

include_recipe 'tomcat::service' template 'tomcat environment configuration' do path ::File.join(node['tomcat']['system_env_dir'], "tomcat#{node['tomcat']['base_version']}") source 'tomcat_env_config.erb' owner 'root' group 'root' mode 0644 backup false notifies :restart, resources(:service => 'tomcat') end template 'tomcat server configuration' do path ::File.join(node['tomcat']['catalina_base_dir'], 'server.xml') source 'server.xml.erb' owner 'root' group 'root' mode 0644 backup false notifies :restart, resources(:service => 'tomcat') end

The recipe first calls tomcat::service, which defines the service if necessary. The bulk of the recipe consists of two template resources, each of which creates a configuration file from one of the cookbook's template files, sets the file properties, and notifies Chef to restart the service.

Tomcat Environment Configuration File

The first template resource uses the tomcat_env_config.erb template file to create a Tomcat environment configuration file, which is used to set environment variables such as JAVA_HOME. The default file name is the template resource's argument. tomcat::container_config uses a path attribute to override the default value and name the configuration file /etc/sysconfig/tomcat6 (Amazon Linux) or /etc/default/tomcat6 (Ubuntu). The template resource also specifies the file's owner, group, and mode settings and directs Chef to not create backup files.

If you look at the source code, there are actually three versions of tomcat_env_config.erb, each in a different subdirectory of the templates directory. The ubuntu and amazon directories contain the templates for their respective operating systems. The default folder contains a dummy template with a single comment line, which is used only if you attempt to run this recipe on an instance with an unsupported operating system. The tomcat::container_config recipe doesn't need to specify which tomcat_env_config.erb to use. Chef automatically picks the appropriate directory for the instance's operating system based on rules described in File Specificity.

The tomcat_env_config.erb files for this example consist largely of comments. To set additional environment variables, just uncomment the appropriate lines and provide your preferred values.

Note

Any configuration setting that might change should be defined as an attribute rather than hardcoded in the template. That way, you don't have to rewrite the template to change a setting, you can just override the attribute.

The Amazon Linux template sets only one environment variable, as shown in the following excerpt.

... # Use JAVA_OPTS to set java.library.path for libtcnative.so #JAVA_OPTS="-Djava.library.path=/usr/lib" JAVA_OPTS="${JAVA_OPTS} <%= node['tomcat']['java_opts'] %>" # What user should run tomcat #TOMCAT_USER="tomcat" ...

JAVA_OPTS can be used to specify Java options such as the library path. Using the default attribute values, the template sets no Java options for Amazon Linux. You can set your own Java options by overriding the ['tomcat']['java_opts'] attribute, for example, by using custom JSON attributes. For an example, see Create a Stack.

The Ubuntu template sets several environment variables, as shown in the following template excerpt.

# Run Tomcat as this user ID. Not setting this or leaving it blank will use the # default of tomcat<%= node['tomcat']['base_version'] %>. TOMCAT<%= node['tomcat']['base_version'] %>_USER=tomcat<%= node['tomcat']['base_version'] %> ... # Run Tomcat as this group ID. Not setting this or leaving it blank will use # the default of tomcat<%= node['tomcat']['base_version'] %>. TOMCAT<%= node['tomcat']['base_version'] %>_GROUP=tomcat<%= node['tomcat']['base_version'] %> ... JAVA_OPTS="<%= node['tomcat']['java_opts'] %>" <% if node['tomcat']['base_version'].to_i < 7 -%> # Unset LC_ALL to prevent user environment executing the init script from # influencing servlet behavior. See Debian bug #645221 unset LC_ALL <% end -%>

Using default attribute values, the template sets the Ubuntu environment variables as follows:

  • TOMCAT6_USER and TOMCAT6_GROUP, which represent the Tomcat user and group, are both set to tomcat6.

    If you set ['tomcat']['base_version'] to tomcat7, the variable names resolve to TOMCAT7_USER and TOMCAT7_GROUP, and both are set to tomcat7.

  • JAVA_OPTS is set to -Djava.awt.headless=true -Xmx128m -XX:+UseConcMarkSweepGC:

    • Setting -Djava.awt.headless to true informs the graphics engine that the instance is headless and does not have a console, which addresses faulty behavior of certain graphical applications.

    • -Xmx128m ensures that the JVM has adequate memory resources, 128MB for this example.

    • -XX:+UseConcMarkSweepGC specifies concurrent mark sweep garbage collection, which helps limit garbage-collection induced pauses.

      For more information, see: Concurrent Mark Sweep Collector Enhancements.

  • If the Tomcat version is less than 7, the template unsets LC_ALL, which addresses a Ubuntu bug.

Note

With the default attributes, some of these environment variables are simply set to their default values. However, explicitly setting environment variables to attributes means you can define custom JSON attributes to override the default attributes and provide custom values. For more information on overriding attributes, see Overriding Attributes.

For the complete template files, see the source code.

Server.xml Configuration File

The second template resource uses server.xml.erb to create the system.xml configuration file, which configures the servlet/JSP container. server.xml.erb contains no operating system-specific settings, so it is in the template directory's default subdirectory.

The template uses standard settings, but it can create a system.xml file for either Tomcat 6 or Tomcat 7. For example, the following code from the template's server section configures the listeners appropriately for the specified version.

<% if node['tomcat']['base_version'].to_i > 6 -%> <!-- Security listener. Documentation at /docs/config/listeners.html <Listener className="org.apache.catalina.security.SecurityListener" /> --> <% end -%> <!--APR library loader. Documentation at /docs/apr.html --> <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" /> <!--Initialize Jasper prior to webapps are loaded. Documentation at /docs/jasper-howto.html --> <Listener className="org.apache.catalina.core.JasperListener" /> <!-- Prevent memory leaks due to use of particular java/javax APIs--> <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" /> <% if node['tomcat']['base_version'].to_i < 7 -%> <!-- JMX Support for the Tomcat server. Documentation at /docs/non-existent.html --> <Listener className="org.apache.catalina.mbeans.ServerLifecycleListener" /> <% end -%> <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" /> <% if node['tomcat']['base_version'].to_i > 6 -%> <Listener className="org.apache.catalina.core.ThreadLocalLeakPreventionListener" /> <% end -%>

The template uses attributes in place of hardcoded settings so you can easily change the settings by defining custom JSON attributes. For example:

<Connector port="<%= node['tomcat']['port'] %>" protocol="HTTP/1.1" connectionTimeout="20000" URIEncoding="<%= node['tomcat']['uri_encoding'] %>" redirectPort="<%= node['tomcat']['secure_port'] %>" />

For more information, see the source code.

tomcat::apache_tomcat_bind

The tomcat::apache_tomcat_bind recipe enables the Apache server to act as Tomcat's front end, receiving incoming requests and forwarding them to Tomcat and returning the responses to the client. This example uses mod_proxy as the Apache proxy/gateway.

execute 'enable mod_proxy for apache-tomcat binding' do command '/usr/sbin/a2enmod proxy' not_if do ::File.symlink?(::File.join(node['apache']['dir'], 'mods-enabled', 'proxy.load')) || node['tomcat']['apache_tomcat_bind_mod'] !~ /\Aproxy/ end end execute 'enable module for apache-tomcat binding' do command "/usr/sbin/a2enmod #{node['tomcat']['apache_tomcat_bind_mod']}" not_if {::File.symlink?(::File.join(node['apache']['dir'], 'mods-enabled', "#{node['tomcat']['apache_tomcat_bind_mod']}.load"))} end include_recipe 'apache2::service' template 'tomcat thru apache binding' do path ::File.join(node['apache']['dir'], 'conf.d', node['tomcat']['apache_tomcat_bind_config']) source 'apache_tomcat_bind.conf.erb' owner 'root' group 'root' mode 0644 backup false notifies :restart, resources(:service => 'apache2') end

To enable mod_proxy, you must enable the proxy module and a protocol-based module. You have two options for the protocol module:

Both the recipe's execute resources run the a2enmod command, which enables the specified module by creating the required symlinks:

  • The first execute resource enables the proxy module.

  • The second execute resource enables the protocol module, which is set to proxy_http by default.

    If you would rather use AJP, you can define custom JSON to override the apache_tomcat_bind_mod attribute and set it to proxy_ajp.

The apache2::service recipe is an AWS OpsWorks Stacks built-in recipe that defines the Apache service. For more information, see the recipe in the AWS OpsWorks Stacks GitHub repository.

The template resource uses apache_tomcat_bind.conf.erb to create a configuration file, named tomcat_bind.conf by default. It places the file in the ['apache']['dir']/.conf.d directory. The ['apache']['dir'] attribute is defined in the built-in apache2 attributes file, and is set by default to /etc/httpd (Amazon Linux), or /etc/apache2 (Ubuntu). If the template resource creates or changes the configuration file, the notifies command schedules an Apache service restart.

<% if node['tomcat']['apache_tomcat_bind_mod'] == 'proxy_ajp' -%> ProxyPass <%= node['tomcat']['apache_tomcat_bind_path'] %> ajp://localhost:<%= node['tomcat']['ajp_port'] %>/ ProxyPassReverse <%= node['tomcat']['apache_tomcat_bind_path'] %> ajp://localhost:<%= node['tomcat']['ajp_port'] %>/ <% else %> ProxyPass <%= node['tomcat']['apache_tomcat_bind_path'] %> http://localhost:<%= node['tomcat']['port'] %>/ ProxyPassReverse <%= node['tomcat']['apache_tomcat_bind_path'] %> http://localhost:<%= node['tomcat']['port'] %>/ <% end -%>

The template uses the ProxyPass and ProxyPassReverse directives to configure the port used to pass traffic between Apache and Tomcat. Because both servers are on the same instance, they can use a localhost URL and are both set by default to http://localhost:8080.