This is a sample application for using database services on Cloud Foundry with the Spring Framework and Spring Boot.
This application has been built to store the same domain objects in one of a variety of different persistence technologies - relational, document, and key-value stores. This is not meant to represent a realistic use case for these technologies, since you would typically choose the one most applicable to the type of data you need to store, but it is useful for testing and experimenting with different types of services on Cloud Foundry.
The application use Spring Java configuration and bean profiles to configure the application and the connection objects needed to use the persistence stores. It also uses the Java CFEnv library to inspect the environment when running on Cloud Foundry. See the Cloud Foundry documentation for details on configuring a Spring application for Cloud Foundry.
This project requires Java version 17 or later to compile.
Note
If you need to use an earlier Java version, check out the spring-boot-2 branch, which can be built with Java 8 and later.
To build a runnable Spring Boot jar file, run the following command:
$ ./gradlew clean assemble
One Spring bean profile should be activated to choose the database provider that the application should use. The profile is selected by setting the system property spring.profiles.active when starting the app.
The application can be started locally using the following command:
$ java -jar -Dspring.profiles.active=<profile> build/libs/spring-music-1.0.jar
where <profile> is one of the following values:
mysqlpostgresmongodbredis
If no profile is provided, an in-memory relational database will be used. If any other profile is provided, the appropriate database server must be started separately. Spring Boot will auto-configure a connection to the database using it's auto-configuration defaults. The connection parameters can be configured by setting the appropriate Spring Boot properties.
If more than one of these profiles is provided, the application will throw an exception and fail to start.
When running on Cloud Foundry, the application will detect the type of database service bound to the application (if any). If a service of one of the supported types (MySQL, Postgres, Oracle, MongoDB, or Redis) is bound to the app, the appropriate Spring profile will be configured to use the database service. The connection strings and credentials needed to use the service will be extracted from the Cloud Foundry environment.
If no bound services are found containing any of these values in the name, an in-memory relational database will be used.
If more than one service containing any of these values is bound to the application, the application will throw an exception and fail to start.
After installing the 'cf' command-line interface for Cloud Foundry, targeting a Cloud Foundry instance, and logging in, the application can be built and pushed using these commands:
$ cf push
The application will be pushed using settings in the provided manifest.yml file. The output from the command will show the URL that has been assigned to the application.
Using the provided manifest, the application will be created without an external database (in the in-memory profile). You can create and bind database services to the application using the information below.
Depending on the Cloud Foundry service provider, persistence services might be offered and managed by the platform. These steps can be used to create and bind a service that is managed by the platform:
# view the services available
$ cf marketplace
# create a service instance
$ cf create-service <service> <service plan> <service name>
# bind the service instance to the application
$ cf bind-service <app name> <service name>
# restart the application so the new service is detected
$ cf restart
Cloud Foundry also allows service connection information and credentials to be provided by a user. In order for the application to detect and connect to a user-provided service, a single uri field should be given in the credentials using the form <dbtype>://<username>:<password>@<hostname>:<port>/<databasename>.
These steps use examples for username, password, host name, and database name that should be replaced with real values.
# create a user-provided Oracle database service instance
$ cf create-user-provided-service oracle-db -p '{"uri":"oracle://root:[email protected]:1521/mydatabase"}'
# create a user-provided MySQL database service instance
$ cf create-user-provided-service mysql-db -p '{"uri":"mysql://root:[email protected]:3306/mydatabase"}'
# bind a service instance to the application
$ cf bind-service <app name> <service name>
# restart the application so the new service is detected
$ cf restart
To test the application with different services, you can simply stop the app, unbind a service, bind a different database service, and start the app:
$ cf unbind-service <app name> <service name>
$ cf bind-service <app name> <service name>
$ cf restart
Database drivers for MySQL, Postgres, Microsoft SQL Server, MongoDB, and Redis are included in the project.
To connect to an Oracle database, you will need to download the appropriate driver (e.g. from http://www.oracle.com/technetwork/database/features/jdbc/index-091264.html). Then make a libs directory in the spring-music project, and move the driver, ojdbc7.jar or ojdbc8.jar, into the libs directory.
In build.gradle, uncomment the line compile files('libs/ojdbc8.jar') or compile files('libs/ojdbc7.jar') and run ./gradle assemble.
By default, the application will be built and deployed using Java 17 compatibility. If you want to use a more recent version of Java, you will need to update two things.
In build.gradle, change the targetCompatibility Java version from JavaVersion.VERSION_17 to a different value from JavaVersion:
java {
...
targetCompatibility = JavaVersion.VERSION_17
}
In manifest.yml, change the Java buildpack JRE version from version: 17.+ to a different value:
JBP_CONFIG_OPEN_JDK_JRE: '{ jre: { version: 17.+ } }'
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