[WFLY-22003] Replace JPA initialization with JDBC CDI bean

[Riovo]

Fixes: https://redhat.atlassian.net/browse/WFLY-22003

Replaces the current JPA-based database initialization with a CDI bean using direct JDBC. This eliminates the WildFly Glow unbound datasource warning that popped up because persistence.xml referenced a CLI-defined datasource.

The CDI bean observes application startup (@observes @initialized(ApplicationScoped.class)) to initialize the H2 database schema and test users for the Elytron JDBC realm.

[luck3y]

LGTM, I added some suggestions, feel free to disagree :)

[emmartins]

Personally I dislike the usage of an EJB for this, I know this was suggested in the original JIRA but EJB is kind of legacy and considered an expensive resource, I suggest instead either:

1. In case DB initialization separated from the Servlet is prefered, to turn DatabaseInitializer into a CDI bean that observes app initialization:

@ApplicationScoped
public class DatabaseInitializer {
    ...
    public void initializeDatabase(@Observes @Initialized(ApplicationScoped.class) Object init) {
       ...
    }
    ...
}

2. Use nothing else than the existing Servlet, overriding its init() method, where you will invoke DatabaseInitializer, and changing the WebServlet annotation to load-init on startup:

@WebServlet(value = "/SecuredServlet", loadOnStartup = 1)
@ServletSecurity(@HttpConstraint(rolesAllowed = { "quickstarts" }))
public class SecuredServlet extends HttpServlet {
    ...
    @Resource(lookup = "java:jboss/datasources/ServletSecurityDS")
    private DataSource dataSource;

    @Override
    public void init() throws ServletException {
        new DatabaseInitializer(dataSource).initializeDatabase();
    }
    ...
}

Either requires no changes to the CLI script, or aditional dependencies.

PS: Ken remarks would still need to be considered.

[Riovo]

Thank you @emmartins and @luck3y for your comments. I have since implemented everything, please let me know if everything is good or if changes need to be done.

[emmartins]

@Riovo please squash all commits into one too :)

[Riovo]

@Riovo please squash all commits into one too :)

Hehe will do, thank you for you time :)

[Riovo]

@darranl