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Datasources Configuration

There are two types of datasources, internal and external.

Internal Datasource

Internal datasources uses one of the drivers that have been provisioned along with the WildFly server. The default configuration contains postgresql and mysql drivers.

To specify internal datasources use the DB_SERVICE_PREFIX_MAPPING environment variable. It has the following format

<POOLNAME>-<DATABASETYPE>=<PREFIX>

For example testa-postgresql=TEST. The other out of the box valid value for DATABASETYPE is mysql.

You can create more than one datasource by using a comma separated list of entries, e.g: DB_SERVICE_PREFIX_MAPPING="testa-postgresql=TEST,test2-postgresql=TEST2”. One datasource or xa-datasource entry will be created per entry in the list.

The PREFIX is used to determine other relevant datasource variables:

  • POOLNAME_DATABASETYPE_SERVICE_HOST

Defines the database server’s host name or IP address to be used in the datasource’s connection-url property. Example value: 192.168.1.3

  • POOLNAME_DATABASETYPE_SERVICE_PORT

Defines the database server’s port for the datasource. Example value: 5432

  • PREFIX_BACKGROUND_VALIDATION

When set to true database connections are validated periodically in a background thread prior to use. Defaults to false, meaning the validate-on-match method is enabled by default instead.

  • PREFIX_BACKGROUND_VALIDATION_MILLIS

Specifies frequency of the validation, in milliseconds, when the background-validation database connection validation mechanism is enabled (PREFIX_BACKGROUND_VALIDATION variable is set to true). Defaults to 10000.

  • PREFIX_CONNECTION_CHECKER

Specifies a connection checker class that is used to validate connections for the particular database in use. Example value: org.jboss.jca.adapters.jdbc.extensions.postgres.PostgreSQLValidConnectionChecker

  • PREFIX_DATABASE

Defines the database name for the datasource. Example value: myDatabase

  • PREFIX_EXCEPTION_SORTER

Specifies the exception sorter class that is used to properly detect and clean up after fatal database connection exceptions. Example value: org.jboss.jca.adapters.jdbc.extensions.mysql.MySQLExceptionSorter

  • PREFIX_JNDI

Defines the JNDI name for the datasource. Defaults to java:jboss/datasources/POOLNAME_DATABASETYPE, where POOLNAME and DATABASETYPE are taken from the triplet described above. This setting is useful if you want to override the default generated JNDI name. Example value: java:jboss/datasources/test-postgresql

  • PREFIX_JTA

Defines Java Transaction API (JTA) option for the non-XA datasource. The XA datasources are already JTA capable by default. Defaults to true.

  • PREFIX_MAX_POOL_SIZE

Defines the maximum pool size option for the datasource. Example value: 20

  • PREFIX_MIN_POOL_SIZE

Defines the minimum pool size option for the datasource. Example value: 1

  • PREFIX_NONXA

Defines the datasource as a non-XA datasource. Defaults to false.

  • PREFIX_PASSWORD

Defines the password for the datasource. Example value: password

  • PREFIX_TX_ISOLATION

Defines the java.sql.Connection transaction isolation level for the datasource. Example value: TRANSACTION_READ_UNCOMMITTED

  • PREFIX_URL

Defines connection URL for the datasource. Example value: jdbc:postgresql://localhost:5432/postgresdb

  • PREFIX_USERNAME

Defines the username for the datasource. Example value: admin

Drivers

When adding drivers to WildFly server, you have 2 choices:

  • Package your drivers (even datasources) as galleon feature-pack as done in wildfly-datasources-galleon-pack and include the Galleon feature-pack in your Galleon project.

  • Use s2i hooks we are offering that allow you to install driver JBOSS modules and update WildFly configuration.

Drivers deployment and configuration using s2i hooks

An example of such approach can be found in this test project.

To be able to deploy a driver module and configure the jdbc-driver resource in datasources subsystem it is necessary to use a special script file called install.sh. This file will be invoked during the assemble phase of the S2I process.

S2I_IMAGE_SOURCE_MOUNTS is the environment variable that instructs the S2I process where to find this file. This variable will contain a comma-separated list of directories where to find the install.sh file.

The following is an example of the content of install.sh script:

#!/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

In this example we are using the following methods exposed by install-common.sh script. This script is available in /usr/local/s2i directory of our image. The methods used by the user define install.sh script are:

  • install_deployments: Copy the file passed as an argument to the server deployment directory.
  • install_modules: Copy all the JBOSS modules in the directory passed as argument to the server modules directory.
  • configure_drivers: Configure the desired drivers using the environment file passed as an argument.

The ${injected_dir} in our example will be one of the directories listed in S2I_IMAGE_SOURCE_MOUNTS variable that is currently being processed.

The ${injected_dir}/drivers.env is a file that will contain the environment variables that you want to use to configure drivers.

The available environment variables that you can configure in this file are:

  • DRIVERS: It's a comma separated list of driver prefixes. And for each prefix:

  • ${driver_prefix}_DRIVER_MODULE

  • ${driver_prefix}_DRIVER_NAME

  • ${driver_prefix}_DRIVER_CLASS

  • ${driver_prefix}_XA_DATASOURCE_CLASS

External datasource

External datasources are datasources that are referencing drivers not present in the default configuration. You configure them by using the same PREFIX_* env variable defined for Internal datasources. In addition you use PREFIX_DRIVER env var to specify the driver name.

To specify external datasources, you can create one or more environment files. These will be read on startup of the server. To configure the environment files, you can do something like:

`ENV_FILES=/etc/extensions/file1.env,/etc/extensions/file2.env`

Then assuming that the image contains the env files in these locations, it will use the prefixes in the DATASOURCES variable contained in the file to look for variables in the file with those prefixes. An example:

$cat /etc/extensions/file1.env
DATASOURCES=MYDB

# The "MYDB" database
#
MYDB_DATABASE=demo
MYDB_DRIVER=mydb-driver
MYDB_JNDI=java:jboss/datasources/MyDBDS
MYDB_USERNAME=demo
MYDB_PASSWORD=demo
MYDB_SERVICE_PORT=5432
MYDB_SERVICE_HOST=hostname
MYDB_JTA=true
MYDB_NONXA=true
MYDB_URL="jdbc:mydb://hostname:5432/demo"

Note: By locating your env file in <application src>/configuration directory it will be automatically copied to $JBOSS_HOME/standalone/configuration directory.

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