I would like to use in my Spring Boot application flywaydb to update / initialize database from SQL alter files on initialization. Java code, that process Flywaydb, should be executed after Spring datasource is created (Flywaydb needs javax.sql.DataSource) BUT before application beans are initialized. I am aware of #DependsOn annotation bud I don't want to avoid to set this on all application beans.
Is there some way how to initialize specific bean in specified order?
Just don't do anything special. Spring Boot has support for Flyway out-of-the-box. There are only 3 steps to take
Add Flyway as a dependency
Put your migration scripts in src/main/resources/db/migration
Start your application
You don't need to add annotations, create beans or use callbacks. The Spring Team already thought of that.
If you want a bean callback to happen exactly once when the application is ready to start, all beans are ready and will not get called again when the context is refreshed then a good Spring Boot recipe is to use the ApplicationReadyEvent like this:
#EventListener(ApplicationReadyEvent.class)
public void onApplicationEvent(ApplicationReadyEvent event) {
// do tasks that should happen once on startup
}
Related
Using Spring Boot 1.5.12, we create scoped proxies for #ConfigurationProperties beans. We do this so that we can effectively have property values that are scoped to the user/session/etc. We use a BeanFactoryPostProcessor to register a scoped proxy created by ScopedProxyUtils.createScopedProxy and change the scope of the target bean definition to our custom scope.
This worked great in Spring Boot 1.5.12. However, in Spring Boot 2, the introduction of the Binder API has made this stop working. This is because when Spring Boot binds #ConfigurationProperties in its ConfigurationPropertiesBindingPostProcessor, it uses Bindable.of(type).withExistingValue(bean) passing in a type (e.g. org.example.Foo) and the bean which is an instance of ScopedProxyFactoryBean. Bindable checks that bean is an instance of type which it's not and things blow up.
Does anyone know of a general way to accomplish this? Specifically, to replace the #ConfigurationProperties bean definition with a proxy while still allowing the properties to bind to the instance? I've considered delaying the creation of the proxy until after the target has already been bound by ConfigurationPropertiesBindingPostProcessor (i.e. in my own BeanPostProcessor). However, at this point the bean is instantiated and my proxy can only replace the bean. It can't really leave the original bean in the context as a target. So I'm struggling with how to do this using a BeanPostProcessor.
EDIT: I've created a simple example project that demonstrates the issue (with the ability to check out code that works on Spring Boot 1 and fails on Spring Boot 2).
I'm currently using an EnvironmentPostProcessor to add my external PropertySource, the code looks like this :
public class ExternalPropertySourceEnvironmentPostProcessor implements EnvironmentPostProcessor
{
private static final String EXTERNAL_PROPERTY_SOURCE_NAME = "ExternalPropertySource";
#Override
public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application)
{
if (environment.acceptsProfiles(Profiles.EXTERNAL_PROPERTY_SOURCE_ENABLED_PROFILE)) {
environment.getPropertySources()
.addLast(new ExternalPropertySource(EXTERNAL_PROPERTY_SOURCE_NAME, new ExternalSource()));
}
}
}
A spring.factories is also used to register this EnvironmentPostProcessor.
This code actually works if the profile is set in the vm environment variables, but if it is added in src/main/resources/application.yml, the profile doesn't seem to be injected yet in the environment and is not returned by the environment.getActiveProfiles(). I've tried using the interface Ordered with the lowest precedence, but it doesn't help.
To add a bit of context around what I'm trying to achieve, this class is in a small library that adds an external property source like a database. Then we can use it in some other spring boot applications. Something like Spring Cloud Config does.
I'd like a clean way to enable or disable this property source depending on the environment where the code runs. I don't mind using something else then profiles or even another way to inject the property source, I just want something clean that doesn't depend on several factors to work.
The main problem in my code right now is that I'm using spring boot's property sources to make my own property source configurable.
UPDATE : I used a Spring Cloud app to debug this, and was confusing the bootstrap context with the normal spring boot context. See my answer below.
Further investigation made me figure out the problem appeared only with a Spring Cloud application.
In fact the breakpoint I had in this code was triggered twice, once after the bootstrap context initialization and once after the spring boot context initialization. I was only debugging the profiles in the first occurence. At that point, only the bootstrap.yml properties are loaded and not the ones from the application.yml file. The second occurence obviously had the profiles from my application.yml file.
My code worked as expected with a vanilla Spring Boot application. As the documentation states :
The Environment has already been prepared with all the usual property
sources that Spring Boot loads by default.
I was confused by the behaviour of my app which seemed to be different from that statement, but it was Spring Cloud's bootstrap that was messing with my debugging.
Since I need a PropertySource that has the highest precedence, I need to add it in the post bootstrap initialization for Spring Cloud apps. I used an init flag on my EnvironmentPostProcessor so it doesn't get executed twice and used the bootstrap.yml on Spring Cloud apps to set the profile.
TL;DR :
With Spring Cloud, an EnvironmentPostProcessor gets called twice: once after the bootstrap init and once after the normal Spring Boot context init. If you need injected properties and are targeting the Spring Cloud's post bootstrap initialization, use the bootstrap.yml instead of application.yml.
I am trying to figure out how can I dynamically update/reload externalized configuration in a Spring Boot application without restarting the whole application.
Most of the advice involves reloading ApplicationContext after changing the externalized configuration, but that is equivalent to restarting the entire application, so this is not really all that useful.
Reading through SpringBoot reference documentation, I found a chapter 23.7 Typesafe Configuration Properties.
If I understand it correctly, this allows to define simple POJO classes that will hold your application (externalized) configuration values as attributes.
In theory at least, this scheme could be used to bind beans only once to the required configuration POJO and upon configuration change just update the values in the POJO. Components could easily pick up the changes next time they access getters on the POJO...
However, I have yet not managed to figure out how to enable this type of behavior. Is there some glaringly obvious way to dynamically update components annotated with #ConfigurationProperties when relevant configuration has changed?
It sounds like you're looking for #RefreshScope which is provided by Spring Cloud. From the Spring Cloud documentation:
A Spring #Bean that is marked as #RefreshScope will get special treatment when there is a configuration change. This addresses the problem of stateful beans that only get their configuration injected when they are initialized. For instance if a DataSource has open connections when the database URL is changed via the Environment, we probably want the holders of those connections to be able to complete what they are doing. Then the next time someone borrows a connection from the pool he gets one with the new URL.
I need to be able to initiate a bean at startup and have it run constantly in the background using some kind of internal event/time loop (looking for data records to process). I was wondering what the correct Java EE 7/ JBoss EAP 6.2 method of doing this would be.
Any ideas?
Use the Quartz Scheduler framework and have the job fire up as configured.
It depends what you want to achieve. There are various ways you can achieve the stated goal. Some i can think of are :-
1)Use spring which automatically instantiate singleton beans on startup and call init method while start up
2)In terms of web app , you can use loadOnstartUp servlet configuration
3)Use quarts Job to run the background jobs
EJBs should work fine in this case (standard Java EE - no external framework needed)
I am assuming you need a 'pull' mode for the data rather than having a component to 'listen' to data events
Spin up a Singleton EJB
Write your business logic which would query the data repository
#Singleton
#Startup //container initializes the bean when it starts or when the application is deployed
public class MySingletonEJB{
#Schedule //configure this annotation as per required schedule e.g. via a Cron like syntax
public void executeJob(){
//.... search data records
}
}
Is there a way to update a Spring bean dynamically if the spring beans configuration changes?
E.g. assume that I have a spring bean with boolean property x and the spring beans has the value true when the application starts.
So spring creates the bean with the property x set to true.
Is there a way so that if I changes the property to x (while the application is running) that the property will be updated e.g. to false?
Calling the setter for x setX() method will do that.
But it should not be a prototype bean.
it is possible with the jrebel-spring integration. it monitors your configuration and TRIES to re-wire your beans at runtime.
Though i would not use it in production...only for playing around, testing etc
Spring reads configuration files at startup. If you really need to update configs while application running, you should manually implement all the chain: detecting config changes, validating config, detecting changed beans, updating beans in context.
Spring beans can be initialized using applicationContext.xml or even programatically. In your case; you will need to remove configurations from xml and add into java program. You can get some idea from How to programmatically create bean definition with injected properties? . Other good links were also available on google.