Memcached Session Manager Cookbook

Installs/Configures Tomcat high-availability clusters with memcached using Martin Grotzke’s
https://code.google.com/p/memcached-session-manager.

Requirements

• This cookbook expects $CATALINA_HOME to be defined in the environment. If $CATALINA_HOME is not defined, then
  please override node['memcached_session_manager']['tomcat']['lib'] attribute.
• Java & Tomcat must be installed outside of this cookbook.
• Chef 11.14 or higher.

Platforms

• CentOS
• RedHat
• Ubuntu

Usage

The default recipe adds required memcached_session_manager jars to Tomcat. Use the attributes below to configure
memcached_session_manager. Note memcached_session_manager_context resource will automatically include the default
recipe.

Attributes

• node['memcached_session_manager']['version'] - The version of memcached_session_manager to install.
• node['memcached_session_manager']['flavor'] - Flavors memcached and couchbase are supported.
  Defaults to memcached.
• node['memcached_session_manager']['tomcat']['base_version'] - Defaults to 7.
• node['memcached_session_manager']['tomcat']['lib'] - Defaults to $CATALINA_HOME/lib/.
  Be sure to override this if $CATALINA_HOME is not defined in your environment.
• node['memcached_session_manager']['memcached']['spymemcached'] -
  The version of spymemcached to install for memcached.
• node['memcached_session_manager']['couchbase']['couchbase-client'] -
  The version of couchbase-client to install for couchbase.
• node['memcached_session_manager']['couchbase']['jettison'] -
  The version of jettison to install for couchbase.
• node['memcached_session_manager']['couchbase']['commons-codec'] -
  The version of commons-codec to install for couchbase.
• node['memcached_session_manager']['couchbase']['httpcore'] -
  The version of httpcore to install for couchbase.
• node['memcached_session_manager']['couchbase']['httpcore-nio'] -
  The version of httpcore-nio to install for couchbase.
• node['memcached_session_manager']['couchbase']['netty'] -
  The version of netty to install for couchbase.

LWRP

memcached_session_manager_context

Updates the element in context.xml so that it contains the Manager configuration for the
memcached-session-manager, like in the examples below.

The following examples show configurations for sticky sessions and non-sticky sessions with memcached servers and
for non-sticky sessions with membase. The examples with memcached servers assume that there are two memcacheds
running, one on host1 and another one on host2. All sample configurations assume that you want to use kryo based
serialization.

Example for sticky sessions + kryo

The following example shows the configuration of the first tomcat, assuming that it runs on host1, together with
memcached “n1”. The attribute failoverNodes=”n1” tells msm to store sessions preferably in memcached “n2” and only
store sessions in “n1” (running on the same host/machine) if no other memcached node (here only n2) is available
(even if host1 goes down completely, the session is still available in memcached “n2” and could be served by the
tomcat on host2). For the second tomcat (on host2) you just need to change the failover node to “n2”, so that it
prefers the memcached “n1”. Everything else should be left unchanged.

memcached_session_manager_context '/path/to/context.xml' do
  memcachedNodes 'n1:host1.yourdomain.com:11211,n2:host2.yourdomain.com:11211'
  failoverNodes 'n1'
  requestUriIgnorePattern '.*\.(ico|png|gif|jpg|css|js)$'
end

Example for non-sticky sessions + kryo

The following example shows a configuration for non-sticky sessions. In this case there’s no need for failoverNodes,
as sessions are served by all tomcats round-robin and they’re not bound to a single tomcat. For non-sticky sessions
the configuration (for both/all tomcats) would look like this:

memcached_session_manager_context '/path/to/context.xml' do
  memcachedNodes 'n1:host1.yourdomain.com:11211,n2:host2.yourdomain.com:11211'
  sticky false
  sessionBackupAsync false
  lockingMode 'uriPattern:/path1|/path2'
  requestUriIgnorePattern '.*\.(ico|png|gif|jpg|css|js)$'
end

Example for non-sticky sessions with couchbase + kryo

To connect to a membase bucket bucket1 the configuration would look like this:

memcached_session_manager_context '/path/to/context.xml' do
  memcachedNodes 'http://host1.yourdomain.com:8091/pools'
  username 'bucket1'
  password 'topsecret'
  memcachedProtocol 'binary'
  sticky false
  sessionBackupAsync false
  requestUriIgnorePattern '.*\.(ico|png|gif|jpg|css|js)$'
end

Example for multiple contexts sharing the same session id

If you are running multiple webapps/contexts sharing the same session id (e.g. by having set sessionCookiePath=”/“)
you must tell memcached session manager to add a prefix to the session id when storing a session in memcached.
For this you can use the storageKeyPrefix attribute as shown by this example (see also the more detailed attribute
description below):

memcached_session_manager_context '/path/to/context.xml' do
  memcachedNodes 'n1:host1.yourdomain.com:11211,n2:host2.yourdomain.com:11211'
  failoverNodes 'n1'
  storageKeyPrefix 'context'
  requestUriIgnorePattern '.*\.(ico|png|gif|jpg|css|js)$'
end

Actions

• install - Adds or updates the element in context.xml so that it contains the Manager configuration for
  the memcached-session-manager.
• remove - Removes the element in context.xml so that it contains the Manager configuration for
  the memcached-session-manager.

Attributes

Documentation below has been trimmed down from the original. Please read the complete documentation
here.

• path (required) - Defaults to name of the resource block. Specifies direct path to context.xml file.
• className - Defaults to de.javakaffee.web.msm.MemcachedBackupSessionManager.
• memcachedNodes (required) - This attribute must contain all memcached nodes you have running, or the membase
  bucket uri(s). It should be the same for all tomcats.
• failoverNodes (optional, must not be used for non-sticky sessions) - Defaults to nil. Specifies ids of the
  memcached nodes that must only be used for session backup when none of the other memcached nodes are available.
  Several memcached node ids are separated by space or comma.
• username - Defaults to nil. Specifies the username used for a membase bucket or SASL.
• password - Defaults to nil. Specifies the password used for membase bucket or SASL authentication
  (can be left empty / omitted if the “default” membase bucket without a password shall be used).
• memcachedProtocol - Defaults to text - Specifies the memcached protocol to use, one of text or
  binary.
• sticky - Defaults to true. Specifies if sticky or non-sticky sessions are used.
• lockingMode (optional, for non-sticky sessions only) - Defaults to none. Specifies the locking strategy
  for non-sticky sessions. Session locking is useful to prevent concurrent modifications and lost updates of the session
  in the case of parallel requests. Session locking is done using memcached. Possible values for lockingMode are:
  none, all, auto, and uriPattern:<regexp>.
• requestUriIgnorePattern - Defaults to nil. Specifies a regular expression for request URIs, that shall not
  trigger a session backup.
• sessionBackupAsync - Defaults to true. Specifies if the session shall be stored asynchronously in memcached.
  If this is true, the backupThreadCount setting is evaluated. If this is false, the timeout set via sessionBackupTimeout
  is evaluated.
• backupThreadCount - Defaults to nil (number-of-cpu-cores). The number of threads that are used for asynchronous
  session backup (if sessionBackupAsync=”true”). For the default value the number of available processors (cores) is used.
• sessionBackupTimeout - Defaults to 100 milliseconds. The timeout in milliseconds after that a session backup is
  considered as being failed. This property is only evaluated if sessions are stored synchronously
  (set via sessionBackupAsync).
• operationTimeout - Defaults to 1000. The memcached operation timeout used at various places, e.g. used for the
  spymemcached ConnectionFactory.
• storageKeyPrefix - Defaults to webappVersion Allows to configure a prefix that’s added to the session id when a
  session is stored in memcached.
• sessionAttributeFilter - Defaults to nil. A regular expression to control which session attributes are serialized
  to memcached.
• transcoderFactoryClass - Defaults to de.javakaffee.web.msm.JavaSerializationTranscoderFactory.
• copyCollectionsForSerialization - Defaults to false. A boolean value that specifies, if iterating over collection
  elements shall be done on a copy of the collection or on the collection itself.
• customConverter - Defaults to nil. Custom converter allow you to provide custom serialization of application
  specific types. Multiple custom converter class names are specified separated by comma (with optional space following
  the comma). Converter classes must be available in the classpath of the web application (place jars in WEB-INF/lib).
• enableStatistics - Defaults to true. A boolean value that specifies, if statistics shall be gathered.
• enabled - Defaults to true. Specifies if session storage in memcached is enabled or not, can also be changed at
  runtime via JMX. Only allowed in sticky mode.

ChefSpec Matchers

This cookbook includes custom ChefSpec matchers you can use to test
your own cookbooks.

Example Matcher Usage

expect(chef_run).to install_memcached_session_manager_context('/path/to/context.xml').with(
  memcachedNodes: 'n1:host1.yourdomain.com:11211,n2:host2.yourdomain.com:11211',
  failoverNodes: 'n1',
  storageKeyPrefix: 'context',
  requestUriIgnorePattern: '.*\.(ico|png|gif|jpg|css|js)$'
)

Cookbook Matchers

• install_memcached_session_manager_context(path)
• remove_memcached_session_manager_context(path)

Getting Help

• Ask specific questions on Stack Overflow.
• Report bugs and discuss potential features in
  Github issues.

Contributing

Please refer to CONTRIBUTING.

License

MIT - see the accompanying LICENSE
file for details.