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Configure an Oracle JNDI DataSource in an Embedded Tomcat with Spring Boot

For those applications migrated from the web servers to Spring Boot platform, if you were using a managed DataSource in a standalone Tomcat server, when coming to Spring Boot based embedded Tomcat, you have to configure a DataSource in the embedded Tomcat.

Spring Boot provides some customizers to append additional configurations to the web server.

For Tomcat server, define a WebServerFactoryCustomizer<TomcatServletWebServerFactory> bean like this.

@Bean
WebServerFactoryCustomizer<TomcatServletWebServerFactory> tomcatFactoryCustomizer(){
    return factory-> {

        TomcatContextCustomizer dataSourceContextCustomizer = context -> {
            var resource = new ContextResource();

            resource.setType(DataSource.class.getName());
            resource.setName("jdbc/testDS");
            resource.setAuth("Container");

            // use tomcat-dbcp.
            resource.setProperty("factory", "org.apache.tomcat.dbcp.dbcp2.BasicDataSourceFactory");
            resource.setProperty("driverClassName", "oracle.jdbc.driver.OracleDriver");
            resource.setProperty("url", "jdbc:oracle:thin:@localhost:1521:xe");
            resource.setProperty("username", "system");
            resource.setProperty("password", "Passw0rd");
            context.getNamingResources().addResource(resource);
        };

        factory.addContextCustomizers(dataSourceContextCustomizer);
    };
}

TomcatServletWebServerFactory provides a addContextCustomizers to add custom TomcatContext which is a mapping to the Context in the tomcat server.xml.

To use common-dbcp2 as connection pool, add tomcat-dbcp to the project classpath. tomcat-dbcp is updated to use common-dbcp2 in the latest Apache Tomcat 9.

<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat-dbcp</artifactId>
    <version>${tomcat.version}</version>
    <scope>runtime</scope>
</dependency>

I have to tried to use HikariCP as connection pool, as described in this question in stackoverflow, it does not work in my example.

Add Jdbc driver as part of the project classpath.

<dependency>
    <groupId>com.oracle.database.jdbc</groupId>
    <artifactId>ojdbc8</artifactId>
    <scope>runtime</scope>
</dependency>

Add the following configuration in the application.properties to tell Spring Boot to autoconfigure a DataSource from JNDI resource.

spring.datasource.jndi-name=java:comp/env/jdbc/testDS

Start up the application, it fails due to an exception like this.

javax.naming.NamingException: No naming context bound to this class loader
...
Failed to instantiate [javax.sql.DataSource]: Factory method 'jndiDataSource' threw exception;
nested exception is javax.naming.NoInitialContextException: Need to specify class name in environment
 or system property, or in an application resource file: java.naming.factory.initial

Declare a TomcatServletWebServerFactory bean, override the getTomcatWebServer to activate naming support in Tomcat.

@Bean
TomcatServletWebServerFactory tomcatFactory() {
    return new TomcatServletWebServerFactory() {
        @Override
        protected TomcatWebServer getTomcatWebServer(Tomcat tomcat) {
            tomcat.enableNaming();
            return super.getTomcatWebServer(tomcat);
        }
    }

Create a profile for integration tests.

<profile>
    <id>it</id>
    <properties>
        <skip.unit.tests>true</skip.unit.tests>
        <skip.integration.tests>false</skip.integration.tests>
    </properties>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <id>pre-integration-test</id>
                        <goals>
                            <goal>start</goal>
                        </goals>
                    </execution>
                    <execution>
                        <id>post-integration-test</id>
                        <goals>
                            <goal>stop</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</profile>

Create an integration test.

class DemoApplicationIT {

    TestRestTemplate restTemplate = new TestRestTemplate();

    @Test
    @DisplayName(" GET '/' should return status 200")
    void getAllPosts() {
        var resEntity = restTemplate.getForEntity("http://localhost:8080/", Post[].class);
        assertThat(resEntity.getStatusCode()).isEqualTo(HttpStatus.OK);

        var posts = resEntity.getBody();
        assertThat(posts.length).isEqualTo(1);
        assertThat(posts[0].getTitle()).contains("Tomcat");
    }

}

Run this test with it maven profile.

mvn verify -Pit

Get the complete codes from spring-playground.

Reference