Tomcat Container

The Tomcat Container allows servlet 2 and 3 web applications to be run. These applications are run as the root web application in a Tomcat container.

Detection Criterion	Existence of a `WEB-INF/` folder in the application directory and Java Main not detected
Tags	`tomcat-instance=⟨version⟩`, `tomcat-lifecycle-support=⟨version⟩`, `tomcat-logging-support=⟨version⟩` `tomcat-redis-store=⟨version⟩` (optional)

Tags are printed to standard output by the buildpack detect script

If the application uses Spring, Spring profiles can be specified by setting the SPRING_PROFILES_ACTIVE environment variable. This is automatically detected and used by Spring. The Spring Auto-reconfiguration Framework will specify the cloud profile in addition to any others.

Configuration

For general information on configuring the buildpack, refer to Configuration and Extension.

The container can be configured by modifying the config/tomcat.yml file in the buildpack fork. The container uses the Repository utility support and so it supports the version syntax defined there.

Name	Description
`access_logging_support.repository_root`	The URL of the Tomcat Access Logging Support repository index (details).
`access_logging_support.version`	The version of Tomcat Access Logging Support to use. Candidate versions can be found in this listing.
`access_logging_support.access_logging`	Set to `enabled` to turn on the access logging support. Default is `disabled`.
`gemfire_store.gemfire.repository_root`	The URL of the GemFire repository index (details).
`gemfire_store.gemfire.version`	The version of GemFire to use. Candidate versions can be found in this listing.
`gemfire_store.gemfire_logging.repository_root`	The URL of the GemFire Logging repository index (details).
`gemfire_store.gemfire_logging.version`	The version of GemFire Logging to use. Candidate versions can be found in this listing.
`gemfire_store.gemfire_logging_api.repository_root`	The URL of the GemFire Logging API repository index (details).
`gemfire_store.gemfire_logging_api.version`	The version of GemFire Logging API to use. Candidate versions can be found in this listing.
`gemfire_store.gemfire_modules.repository_root`	The URL of the GemFire Modules repository index (details).
`gemfire_store.gemfire_modules.version`	The version of GemFire Modules to use. Candidate versions can be found in this listing.
`gemfire_store.gemfire_modules_tomcat7.repository_root`	The URL of the GemFire Modules Tomcat 7 repository index (details).
`gemfire_store.gemfire_modules_tomcat7.version`	The version of GemFire Modules Tomcat 7 to use. Candidate versions can be found in this listing.
`gemfire_store.gemfire_security.repository_root`	The URL of the GemFire Security repository index (details).
`gemfire_store.gemfire_security.version`	The version of GemFire Security to use. Candidate versions can be found in this listing.
`lifecycle_support.repository_root`	The URL of the Tomcat Lifecycle Support repository index (details).
`lifecycle_support.version`	The version of Tomcat Lifecycle Support to use. Candidate versions can be found in this listing.
`logging_support.repository_root`	The URL of the Tomcat Logging Support repository index (details).
`logging_support.version`	The version of Tomcat Logging Support to use. Candidate versions can be found in this listing.
`redis_store.connection_pool_size`	The Redis connection pool size. Note that this is per-instance, not per-application.
`redis_store.database`	The Redis database to connect to.
`redis_store.repository_root`	The URL of the Redis Store repository index (details).
`redis_store.timeout`	The Redis connection timeout (in milliseconds).
`redis_store.version`	The version of Redis Store to use. Candidate versions can be found in this listing.
`tomcat.repository_root`	The URL of the Tomcat repository index (details).
`tomcat.version`	The version of Tomcat to use. Candidate versions can be found in this listing.

Additional Resources

The container can also be configured by overlaying a set of resources on the default distribution. To do this, add files to the resources/tomcat directory in the buildpack fork. For example, to override the default logging.properties add your custom file to resources/tomcat/conf/logging.properties.

Session Replication

By default, the Tomcat instance is configured to store all Sessions and their data in memory. Under certain cirmcumstances it my be appropriate to persist the Sessions and their data to a repository. When this is the case (small amounts of data that should survive the failure of any individual instance), the buildpack can automatically configure Tomcat to do so by binding an appropriate service.

Redis

To enable Redis-based session replication, simply bind a Redis service containing a name, label, or tag that has session-replication as a substring.

GemFire

To enable GemFire-based session replication, simply bind a GemFire service containing a name, label, or tag that has session_replication as a substring. GemFire services intended to be used for session replication will automatically have a tag of 'session_replication'.

Managing Entropy

Entropy from /dev/random is used heavily to create session ids, and on startup for initializing SecureRandom, which can then cause instances to fail to start in time (see the Tomcat wiki). Also, the entropy is shared so it's possible for a single app to starve the DEA of entropy and cause apps in other containers that make use of entropy to be blocked. If this is an issue then configuring /dev/urandom as an alternative source of entropy may help. It is unlikely, but possible, that this may cause some security issues which should be taken in to account.

Example in a manifest.yml

env:
  JAVA_OPTS: -Djava.security.egd=file:///dev/urandom

Supporting Functionality

Additional supporting functionality can be found in the java-buildpack-support Git repository.

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