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Chapter 3. Configuring the JBoss EAP for OpenShift Image for Your Java Application

The JBoss EAP for OpenShift image is preconfigured for basic use with your Java applications. However, you can configure the JBoss EAP instance inside the image. The recommended method is to use the OpenShift S2I process, together with application template parameters and environment variables.

Important

Any configuration changes made on a running container will be lost when the container is restarted or terminated.

This includes any configuration changes made using scripts that are included with a traditional JBoss EAP installation, for example add-user.sh or the management CLI.

It is strongly recommended that you use the OpenShift S2I process, together with application template parameters and environment variables, to make any configuration changes to the JBoss EAP instance inside the JBoss EAP for OpenShift image.

3.1. How the JBoss EAP for OpenShift S2I Process Works
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Note

The variable EAP_HOME is used to denote the path to the JBoss EAP installation inside the JBoss EAP for OpenShift image.

The S2I process for JBoss EAP for OpenShift works as follows:

  1. If a pom.xml file is present in the source code repository, a Maven build process is triggered that uses the contents of the $MAVEN_ARGS environment variable.

    Although you can specify custom Maven arguments or options with the $MAVEN_ARGS environment variable, Red Hat recommends that you use the $MAVEN_ARGS_APPEND environment variable to do this. The $MAVEN_ARGS_APPEND variable takes the default arguments from $MAVEN_ARGS and appends the options from $MAVEN_ARGS_APPEND to it.

    By default, the OpenShift profile uses the Maven package goal, which includes system properties for skipping tests (-DskipTests) and enabling the Red Hat GA repository (-Dcom.redhat.xpaas.repo).

    Note

    To use Maven behind a proxy on JBoss EAP for OpenShift image, set the $HTTP_PROXY_HOST and $HTTP_PROXY_PORT environment variables. Optionally, you can also set the $HTTP_PROXY_USERNAME, HTTP_PROXY_PASSWORD, and HTTP_PROXY_NONPROXYHOSTS variables.

  2. The results of a successful Maven build are copied to the EAP_HOME/standalone/deployments/ directory inside the JBoss EAP for OpenShift image. This includes all JAR, WAR, and EAR files from the source repository specified by the $ARTIFACT_DIR environment variable. The default value of $ARTIFACT_DIR is the Maven target directory.
  3. All files in the configuration source repository directory are copied to the EAP_HOME/standalone/configuration/ directory inside the JBoss EAP for OpenShift image. If you want to use a custom JBoss EAP configuration file, it should be named standalone-openshift.xml.
  4. All files in the modules source repository directory are copied to the EAP_HOME/modules/ directory inside the JBoss EAP for OpenShift image.

See Artifact Repository Mirrors for additional guidance on how to instruct the S2I process to utilize the custom Maven artifacts repository mirror.

3.2. Configuring JBoss EAP for OpenShift Using Environment Variables
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Using environment variables is the recommended method of configuring the JBoss EAP for OpenShift image. See the OpenShift documentation for instructions on specifying environment variables for application containers and build containers.

For example, you can set the JBoss EAP instance’s management username and password using environment variables when creating your OpenShift application: 

oc new-app --template=eap71-basic-s2i \
 -p IMAGE_STREAM_NAMESPACE="eap-demo" \
 -p SOURCE_REPOSITORY_URL="https://github.com/jboss-developer/jboss-eap-quickstarts" \
 -p SOURCE_REPOSITORY_REF="7.1.0.GA" \
 -p CONTEXT_DIR="kitchensink" \
 -e ADMIN_USERNAME=myspecialuser \
 -e ADMIN_PASSWORD=myspecialp@ssw0rd
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Available environment variables for the JBoss EAP for OpenShift image are listed in Reference Information.

3.3. Build Extensions and Project Artifacts
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The JBoss EAP for OpenShift image extends database support in OpenShift using various artifacts. These artifacts are included in the built image through different mechanisms:

  • S2I artifacts that are injected into the image during the S2I process.
  • Runtime artifacts from environment files provided through the OpenShift Secret mechanism.
Build Extensions Process
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Build Extensions Process

3.3.1. S2I Artifacts
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The S2I artifacts include modules, drivers, and additional generic deployments that provide the necessary configuration infrastructure required for the deployment. This configuration is built into the image during the S2I process so that only the datasources and associated resource adapters need to be configured at runtime.

See Artifact Repository Mirrors for additional guidance on how to instruct the S2I process to utilize the custom Maven artifacts repository mirror.

3.3.1.1. Modules, Drivers, and Generic Deployments
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There are a few options for including these S2I artifacts in the JBoss EAP for OpenShift image:

  1. Include the artifact in the application source deployment directory. The artifact is downloaded during the build and injected into the image. This is similar to deploying an application on the JBoss EAP for OpenShift image.

  2. Include the CUSTOM_INSTALL_DIRECTORIES environment variable, a list of comma-separated list of directories used for installation and configuration of artifacts for the image during the S2I process. There are two methods for including this information in the S2I:

    • An install.sh script in the nominated installation directory. The install script executes during the S2I process and operates with impunity.

      install.sh Script Example

      #!/bin/bash

injected_dir=$1
source /usr/local/s2i/install-common.sh
install_deployments ${injected_dir}/injected-deployments.war
install_modules ${injected_dir}/modules
configure_drivers ${injected_dir}/drivers.env
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      The install.sh script is responsible for customizing the base image using APIs provided by install-common.sh. install-common.sh contains functions that are used by the install.sh script to install and configure the modules, drivers, and generic deployments.

      Functions contained within install-common.sh:

      • install_modules
      • configure_drivers

      • install_deployments

        Modules

        A module is a logical grouping of classes used for class loading and dependency management. Modules are defined in the EAP_HOME/modules/ directory of the application server. Each module exists as a subdirectory, for example EAP_HOME/modules/org/apache/. Each module directory then contains a slot subdirectory, which defaults to main and contains the module.xml configuration file and any required JAR files.

        Example module.xml File

        <?xml version="1.0" encoding="UTF-8"?>
<module xmlns="urn:jboss:module:1.0" name="org.apache.derby">
    <resources>
        <resource-root path="derby-10.12.1.1.jar"/>
        <resource-root path="derbyclient-10.12.1.1.jar"/>
    </resources>
    <dependencies>
        <module name="javax.api"/>
        <module name="javax.transaction.api"/>
    </dependencies>
</module>
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        The install_modules function in install.sh copies the respective JAR files to the modules directory in JBoss EAP, along with the module.xml.

        Drivers

        Drivers are installed as modules. The driver is then configured in install.sh by the configure_drivers function, the configuration properties for which are defined in a runtime artifact environment file.

        Example drivers.env File

        #DRIVER
DRIVERS=DERBY
DERBY_DRIVER_NAME=derby
DERBY_DRIVER_MODULE=org.apache.derby
DERBY_DRIVER_CLASS=org.apache.derby.jdbc.EmbeddedDriver
DERBY_XA_DATASOURCE_CLASS=org.apache.derby.jdbc.EmbeddedXADataSource
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        Generic Deployments

        Deployable archive files, such as JARs, WARs, RARs, or EARs, can be deployed from an injected image using the install_deployments function supplied by the API in install-common.sh.

    • If the CUSTOM_INSTALL_DIRECTORIES environment variable has been declared but no install.sh scripts are found in the custom installation directories, the following artifact directories will be copied to their respective destinations in the built image:

      • modules/* copied to $JBOSS_HOME/modules/system/layers/openshift
      • configuration/* copied to $JBOSS_HOME/standalone/configuration
      • deployments/* copied to $JBOSS_HOME/standalone/deployments

      This is a basic configuration approach compared to the install.sh alternative, and requires the artifacts to be structured appropriately.

3.3.2. Runtime Artifacts
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3.3.2.1. Datasources
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There are three types of datasources:

  1. Default internal datasources. These are PostgreSQL, MySQL, and MongoDB. These datasources are available on OpenShift by default through the Red Hat Registry and do not require additional environment files to be configured. Set the DB_SERVICE_PREFIX_MAPPING environment variable to the name of the OpenShift service for the database to be discovered and used as a datasource.
  2. Other internal datasources. These are datasources not available by default through the Red Hat Registry but run on OpenShift. Configuration of these datasources is provided by environment files added to OpenShift Secrets.
  3. External datasources that are not run on OpenShift. Configuration of external datasources is provided by environment files added to OpenShift Secrets.

Example: Datasource Environment File

# derby datasource
ACCOUNTS_DERBY_DATABASE=accounts
ACCOUNTS_DERBY_JNDI=java:/accounts-ds
ACCOUNTS_DERBY_DRIVER=derby
ACCOUNTS_DERBY_USERNAME=derby
ACCOUNTS_DERBY_PASSWORD=derby
ACCOUNTS_DERBY_TX_ISOLATION=TRANSACTION_READ_UNCOMMITTED
ACCOUNTS_DERBY_JTA=true

# Connection info for xa datasource
ACCOUNTS_DERBY_XA_CONNECTION_PROPERTY_DatabaseName=/home/jboss/source/data/databases/derby/accounts

# _HOST and _PORT are required, but not used
ACCOUNTS_DERBY_SERVICE_HOST=dummy
ACCOUNTS_DERBY_SERVICE_PORT=1527
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The DATASOURCES property is a comma-separated list of datasource property prefixes. These prefixes are then appended to all properties for that datasource. Multiple datasources can then be included in a single environment file. Alternatively, each datasource can be provided in separate environment files.

Datasources contain two types of properties: connection pool-specific properties and database driver-specific properties. Database driver-specific properties use the generic XA_CONNECTION_PROPERTY, because the driver itself is configured as a driver S2I artifact. The suffix of the driver property is specific to the particular driver for the datasource.

In the above example, ACCOUNTS is the datasource prefix, XA_CONNECTION_PROPERTY is the generic driver property, and DatabaseName is the property specific to the driver.

The datasources environment files are added to the OpenShift Secret for the project. These environment files are then called within the template using the ENV_FILES environment property, the value of which is a comma-separated list of fully qualified environment files as shown below. 

{
    “Name”: “ENV_FILES”,
    “Value”: “/etc/extensions/datasources1.env,/etc/extensions/datasources2.env”
}
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3.3.2.2. Resource Adapters
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Configuration of resource adapters is provided by environment files added to OpenShift Secrets.

Expand
Table 3.1. Resource Adapter Properties
AttributeDescription

PREFIX_ID

The identifier of the resource adapter as specified in the server configuration file.

PREFIX_ARCHIVE

The resource adapter archive.

PREFIX_MODULE_SLOT

The slot subdirectory, which contains the module.xml configuration file and any required JAR files.

PREFIX_MODULE_ID

The JBoss Module ID where the object factory Java class can be loaded from.

PREFIX_CONNECTION_CLASS

The fully qualified class name of a managed connection factory or admin object.

PREFIX_CONNECTION_JNDI

The JNDI name for the connection factory.

PREFIX_PROPERTY_ParentDirectory

Directory where the data files are stored.

PREFIX_PROPERTY_AllowParentPaths

Set AllowParentPaths to false to disallow .. in paths. This prevents requesting files that are not contained in the parent directory.

PREFIX_POOL_MAX_SIZE

The maximum number of connections for a pool. No more connections will be created in each sub-pool.

PREFIX_POOL_MIN_SIZE

The minimum number of connections for a pool.

PREFIX_POOL_PREFILL

Specifies if the pool should be prefilled. Changing this value requires a server restart.

PREFIX_POOL_FLUSH_STRATEGY

How the pool should be flushed in case of an error. Valid values are: FailingConnectionOnly (default), IdleConnections, and EntirePool.

The RESOURCE_ADAPTERS property is a comma-separated list of resource adapter property prefixes. These prefixes are then appended to all properties for that resource adapter. Multiple resource adapter can then be included in a single environment file. In the example below, MYRA is used as the prefix for a resource adapter. Alternatively, each resource adapter can be provided in separate environment files.

Example: Resource Adapter Environment File

#RESOURCE_ADAPTER
RESOURCE_ADAPTERS=MYRA
MYRA_ID=myra
MYRA_ARCHIVE=myra.rar
MYRA_CONNECTION_CLASS=org.javaee7.jca.connector.simple.connector.outbound.MyManagedConnectionFactory
MYRA_CONNECTION_JNDI=java:/eis/MySimpleMFC
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The resource adapter environment files are added to the OpenShift Secret for the project namespace. These environment files are then called within the template using the ENV_FILES environment property, the value of which is a comma-separated list of fully qualified environment files as shown below. 

{
    "Name": "ENV_FILES",
    "Value": "/etc/extensions/resourceadapter1.env,/etc/extensions/resourceadapter2.env"
}
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3.4. Deployment Considerations for the JBoss EAP for OpenShift Image
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3.4.1. Scaling Up and Persistent Storage Partitioning
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There are two methods for deploying JBoss EAP with persistent storage: single-node partitioning, and multi-node partitioning.

Single-node partitioning stores the JBoss EAP data store directory, including transaction data, in the storage volume.

Multi-node partitioning creates additional, independent split-n directories to store the transaction data for each JBoss EAP pod, where n is an incremental integer. This communication is not altered if a JBoss EAP pod is updated, goes down unexpectedly, or is redeployed. When the JBoss EAP pod is operational again, it reconnects to the associated split directory and continues as before. If a new JBoss EAP pod is added, a corresponding split-n directory is created for that pod.

To enable the multi-node configuration you must set the SPLIT_DATA parameter to true. This results in the server creating independent split-n directories for each instance within the persistent volume which are used as their data store.

This is now the default setting in the eap71-tx-recovery-s2i template.

Important

Due to the different storage methods of single-node and multi-node partitioning, changing a deployment from single-node to multi-node results in the application losing all data previously stored in the data directory, including messages, transaction logs, and so on. This is also true if changing a deployment from multi-node to single-node, as the storage paths will not match.

3.4.2. Scaling Down and Transaction Recovery
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When the JBoss EAP for OpenShift image is deployed using a multi-node configuration, it is possible for unexpectedly terminated transactions to be left in the data directory of a terminating pod if the cluster is scaled down.

In order to prevent transactions from remaining within the data store of the terminating pod until the cluster next scales up, the eap71-tx-recovery-s2i JBoss EAP template creates a second deployment containing a migration pod that is responsible for managing the migration of transactions. The migration pod scans each independent split-n directory within the JBoss EAP persistent volume, identifies data stores associated with the pods that are terminating, and continues to run until all transactions on the terminating pod are completed.

Important

Since the persistent volume needs to be accessed in read-write mode by both the JBoss EAP application pod and also by the migration pod, it needs to be created with the ReadWriteMany access mode. This access mode is currently only supported for persistent volumes using GlusterFS and NFS plug-ins. For details, see the Supported Access Modes for Persistent Volumes table.

For more information, see Example Workflow: Automated Transaction Recovery Feature When Scaling Down a Cluster, which demonstrates the automated transaction recovery feature of the JBoss EAP for OpenShift image when scaling down a cluster.

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