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03A - Bind the application to a PostgreSQL database

This guide is part of the migrate Java EE app to Azure training

Bind the application to the petstore database in Azure Database for PostgreSQL.

Configure PostgreSQL Data Source

There are 3 steps to configure a data source. These steps are similar to configuring data sources in any on premise Java EE app servers:

Step 1: Understand how to configure JBoss EAP

In App Service, each instance of an app server is stateless. Therefore, each instance must be configured on startup to support a JBoss EAP configuration needed by your application. You can configure at startup by supplying a startup Bash script that calls JBoss/WildFly CLI commands to setup data sources, messaging providers and any other dependencies. We will create a startup.sh script and place it in the /home directory of the Web app. The script will:

Install a JBoss EAP module:

# where resources point to JDBC driver for PostgreSQL
# and module xml points to module description, see below

module add --name=org.postgres --resources=/home/site/libs/postgresql-42.2.5.jar --module-xml=/home/site/scripts/postgresql-module.xml

Where postgresql-module.xml describes the module:

<?xml version="1.0" ?>
<module xmlns="urn:jboss:module:1.1" name="org.postgres">
    <resources>
     <!-- ***** IMPORTANT : PATH should point to PostgreSQL Java driver on App Service Linux *******-->
       <resource-root path="/home/site/libs/postgresql-42.2.5.jar" />
    </resources>
    <dependencies>
        <module name="javax.api"/>
        <module name="javax.transaction.api"/>
    </dependencies>
</module>

Add a JDBC driver for PostgreSQL:

/subsystem=datasources/jdbc-driver=postgres:add(driver-name="postgres",driver-module-name="org.postgres",driver-class-name=org.postgresql.Driver,driver-xa-datasource-class-name=org.postgresql.xa.PGXADataSource)

Install a data source by using the data-source shortcut command:

data-source add --name=postgresDS --driver-name=postgres --jndi-name=java:jboss/datasources/postgresDS --connection-url=${POSTGRES_CONNECTION_URL,env.POSTGRES_CONNECTION_URL:jdbc:postgresql://db:5432/postgres} --user-name=${POSTGRES_SERVER_ADMIN_FULL_NAME,env.POSTGRES_SERVER_ADMIN_FULL_NAME:postgres} --password=${POSTGRES_SERVER_ADMIN_PASSWORD,env.POSTGRES_SERVER_ADMIN_PASSWORD:example} --use-ccm=true --max-pool-size=5 --blocking-timeout-wait-millis=5000 --enabled=true --driver-class=org.postgresql.Driver --exception-sorter-class-name=org.jboss.jca.adapters.jdbc.extensions.postgres.PostgreSQLExceptionSorter --jta=true --use-java-context=true --valid-connection-checker-class-name=org.jboss.jca.adapters.jdbc.extensions.postgres.PostgreSQLValidConnectionChecker

A server reload may be required for the changes to take effect:

reload --use-current-server-config=true

These JBoss CLI commands, JDBC driver for PostgreSQL and module XML are available in initial-postgresql/agoncal-application-petstore-ee7/.scripts

Also, you can directly download the latest version of JDBC driver for PostgreSQL

Step 2: Deploy multiple artifacts to App Service linux

Open pom.xml and update the deployment with the following configuration and run mvn azure-webapp:deploy to deploy.

<deployment>
  <resources>
    <resource>
      <type>war</type>
      <directory>${project.basedir}/target</directory>
      <includes>
        <include>*.war</include>
      </includes>
    </resource>
    <resource>
      <type>lib</type>
      <directory>${project.basedir}/.scripts/3A-postgresql</directory>
      <includes>
        <include>*.jar</include>
      </includes>
    </resource>
    <resource>
      <type>startup</type>
      <directory>${project.basedir}/.scripts/3A-postgresql</directory>
      <includes>
        <include>*.sh</include>
      </includes>
    </resource>
    <resource>
      <type>script</type>
      <directory>${project.basedir}/.scripts/3A-postgresql</directory>
      <includes>
        <include>*.cli</include>
        <include>*.xml</include>
      </includes>
    </resource>
  </resources>
</deployment>

Step 3: Set PostgreSQL database connection info in the Web app environment

Use Azure CLI to set database connection info:

az webapp config appsettings set \
    --resource-group ${RESOURCE_GROUP} --name ${WEBAPP} \
    --settings \
    POSTGRES_CONNECTION_URL=${POSTGRES_CONNECTION_URL} \
    POSTGRES_SERVER_ADMIN_PASSWORD=${POSTGRES_SERVER_ADMIN_PASSWORD} \
    POSTGRES_SERVER_ADMIN_FULL_NAME=${POSTGRES_SERVER_ADMIN_FULL_NAME}
[
 {
   "name": "WEBSITE_HTTPLOGGING_RETENTION_DAYS",
   "slotSetting": false,
   "value": "3"
 },
 {
   "name": "POSTGRES_CONNECTION_URL",
   "slotSetting": false,
   "value": "jdbc:postgresql://petstore-db.postgres.database.azure.com:5432/postgres?ssl=true"
 },
 {
   "name": "POSTGRES_SERVER_ADMIN_PASSWORD",
   "slotSetting": false,
   "value": "======= MASKED ======="
 },
 {
   "name": "POSTGRES_SERVER_ADMIN_FULL_NAME",
   "slotSetting": false,
   "value": "postgres@petstore-db"
 }
]

For additional info, please refer to:

Build Java EE application to interact with Azure Database for PostgreSQL

# Use the Maven profile for PostgreSQL to build from the project base directory
cd ../..
mvn package -Dmaven.test.skip=true -Ddb=postgresql

Note - the postgresql Maven profile is available here.

Deploy to App Service Linux

Deploy to JBoss EAP in App Service Linux:

mvn azure-webapp:deploy

Open Java EE application running on App Service Linux and interacting with Azure Database for PostgreSQL

open https://${WEBAPP}.azurewebsites.net

Log into Azure Database for PostgreSQL and validate tables were created and populated

psql --host=${POSTGRES_SERVER_FULL_NAME} --port=5432 \
    --username=${POSTGRES_SERVER_ADMIN_FULL_NAME} \
    --dbname=${POSTGRES_DATABASE_NAME} --set=sslmode=require

Password for user postgres@petstore-db:
psql (11.1, server 9.6.10)
SSL connection (protocol: TLSv1.2, cipher: ECDHE-RSA-AES256-SHA384, bits: 256, compression: off)
Type "help" for help.

postgres=> \l
postgres=> \dt
               List of relations
 Schema |        Name        | Type  |  Owner
--------+--------------------+-------+----------
 public | category           | table | postgres
 public | country            | table | postgres
 public | customer           | table | postgres
 public | item               | table | postgres
 public | order_line         | table | postgres
 public | product            | table | postgres
 public | purchase_order     | table | postgres
 public | t_order_order_line | table | postgres
(8 rows)

postgres=> select name from category;
   name
----------
 Fish
 Dogs
 Reptiles
 Cats
 Birds
(5 rows)

postgres=> \q

Troubleshoot Java EE application on Azure by viewing logs

Open Java Web app remote log stream from a local machine:

az webapp log tail --name ${WEBAPP} --resource-group ${RESOURCE_GROUP}

⬅️ Previous guide: 02 - Create a database

➡️ Next guide: 04 - Monitor Java EE application