How to change and reload application configuration using a jax-rs service - spring

I have to provide the user of my application, a resource end point with which he should be able to configure the application properties. The property class should be singleton. How can I achieve this. I am using springboot.
What I tried:
I did some reading on actuators, but it seems to work on application.properties,
but I need to use a rest service to configure the properties.

Related

Open API (Swagger) non working in Spring Boot when adding context path

I have a Spring Boot application exposing REST services that are easily called on addresses like
http://localhost:8080/<controller_mapping>/<service_mapping>.
I've been asked to modify my settings in order to add a context path and have my services to respond on
http://localhost:8080//gesev-mensa/<controller_mapping>/<service_mapping>.
Thus I edited my application.properties adding
server.servlet.context-path=/gesev-mensa
Everything works but I can't call Swagger on old address
http://localhost:8080/swagger-ui/index.html?configUrl=/v3/api-docs/swagger-config#/
I get the error Failed to load remote configuration
As suggested, I tried to add property
springdoc.swagger-ui.path=/gesev-mensa/swagger-ui/index.html
but problem persists.
I guess Swagger should be reachable at
http://localhost:8080/gesev-mensa/swagger-ui/index.html?configUrl=/v3/api-docs/swagger-config#/
but that doesn't work.
Any hint?
Thanks for support.
Try removing
springdoc.swagger-ui.path=/gesev-mensa/swagger-ui/index.html
from your properties,
And your swagger will be available in
http://localhost:8080/gesev-mensa/swagger-ui/index.html
As per your current configuration with,
springdoc.swagger-ui.path=/gesev-mensa/swagger-ui/index.html
Swagger will be available in
http://localhost:8080/gesev-mensa/gesev-mensa/swagger-ui/index.html

Spring Cloud Config and Spring Cloud Vault order of initialization

We are leveraging Spring Cloud Config and Spring Cloud Config Vault. We would like to know if there is a way to "bootstrap the bootstrap", ie we want spring cloud config server to be hit and then pull properties from that to leverage in our vault configuration. We looked at order, but it didn't appear to work, and I assume it is because of the post processing order, but I was hoping I might be missing something.
TL;DR
It doesn't work.
Explanation
What Spring Cloud does with its bootstrap context, is setting up an application context that contains a set of PropertySources initialized from Spring beans. The bootstrap context is used then as parent context for the actual context created by Spring Boot. A property lookup looks for properties in its own context and within the parent context.
Configuration properties are initialized very early in the startup process and they use properties from the current Environment. At the time ConfigurationProperties beans are initialized, the Environment does not yet contain any remote PropertySources.
The only option I see here (except creating a bootstrap-bootstrap-context) is using the Spring Cloud Config client within your main class and contribute Vault properties before any Spring context is built.
Probably you can, but it requires PropertySourceBootstrapConfiguration#initialize() method overriding. You can't disable bean PropertySourceBootstrapConfiguration, but you can disable it's initialize method by using applicationContext.getBeanFactory().getBean(PropertySourceBootstrapConfiguration.class).setPropertySourceLocators(new ArrayList<>()) in CustomPropertySourceBootstrapConfiguration (to avoid obsolete external property sources calls).
In your CustomPropertySourceBootstrapConfiguration#initialize method you can retrieve properties from config-server and then customize your vaultPropertySourceLocator by inserting generated in config-server secretId of token.
Don't forget to add your CustomPropertySourceBootstrapConfiguration to spring.factories.
So, it's not easy but it is possible.
We created the custom datasource using EnvironmentPostProcessor which will get called before autoconfigure beans
https://docs.spring.io/spring-boot/docs/current/reference/html/howto.html#howto.application.customize-the-environment-or-application-context

Is it possible to access the spring context outside of a spring-boot application?

I am trying to create a standalone database application which can offer CRUD operations to other applications/modules...
I am aware of the need to create the entities and services used by the application in another artifact since you cannot depend on a spring-boot application alone.
But, can one get the runtime spring-configuration of a spring-boot application? So one can access a service that is deployed on my application?
For best through-put I am looking for a way to use services on a running spring-boot database application on the same JVM in order to minimise overhead...
RMI
What you want is technically it is possible using basic Java RMI (remote method invocation), you just register the bean as the implementation instance and share the interface between the two JVMs, either on localhost or even on different machines.
Spring even gives some additional support for this using RmiProxyFactoryBean, see Spring Remoting RMI article.
From above article, you can export it, using:
#Bean
RmiServiceExporter exporter(CabBookingService implementation) {
Class<CabBookingService> serviceInterface = CabBookingService.class;
RmiServiceExporter exporter = new RmiServiceExporter();
exporter.setServiceInterface(serviceInterface);
exporter.setService(implementation);
exporter.setServiceName(serviceInterface.getSimpleName());
exporter.setRegistryPort(1099);
return exporter;
}
and import it, using:
#Bean
RmiProxyFactoryBean service() {
RmiProxyFactoryBean rmiProxyFactory = new RmiProxyFactoryBean();
rmiProxyFactory.setServiceUrl("rmi://localhost:1099/CabBookingService");
rmiProxyFactory.setServiceInterface(CabBookingService.class);
return rmiProxyFactory;
}
Then you can use it in your application context based on your interface.
However I would not suggest to share beans like this because it has the same problem RMI has.
Shared library
Another way to do what you want is to create a shared library that can be included in other projects.
If all the project, which want to use it are Spring Boot application you can create a Spring Boot starter, see Spring documentation.
This way, other applications just have to add the dependency and they already has access to the beans in their application context, as well as the shared domain objects.
If other application use just regular Spring, they can just #Import your main configuration class.
If other apps are using Java, but not Spring, you can still use Spring inside, just provide a factory, which creates an internal Spring context.
REST service
If other applications are not written in Java, your best bet is to expose a REST interface for them to use the database applications.

Spring boot - how to modify config properties from an external application

I have a spring boot application and it has an application.yml file that contains a bunch of properties. I am writing a separate test harness for this application and using that application I would like to modify some properties after the main application starts up. I am thinking that I need to add a new REST endpoint that will implement the PUT method and will change the properties. Using that PUT method I should be able to change any property that is defined in the application.yml file. Is that the correct approach. Is there a sample application that I can take a look at.

Having spring bean properties refreshed automatically from properties file

I'm using Spring 2.5.6. I have a bean whose properties are being assign from a property file via a PropertyPlaceholderConfigurer. I'm wondering whether its possible to have the property of the bean updated when the property file is modified. There would be for example some periodic process which checks the last modified date of the property file, and if it has changed, reload the bean.
I'm wondering if there is already something that satisfies my requirements. If not, what would be the best approach to solving this problem?
Thanks for your help.
Might also look into useing Spring's PropertyOverrideConfigurer. Could re-read the properties and re-apply it in some polling/schedular bean.
It does depend on how the actual configured beans use these properties. They might, for example, indirectly cache them somewhere themself.
If you want dynamic properties at runtime, perhaps another way to do it is JMX.
One way to do this is to embed a groovy console in your application. Here's some instructions. They were very simple to do, btw - took me very little time even though I'm not that familiar with groovy.
Once you do that you can simply go into the console and change values inside the live application on the fly.
You might try to use a custom scope for the bean that recreates beans on changes of the properties file. See my more extensive answer here.
Spring Cloud Config has facilities to change configuration properties at runtime via the Spring Cloud Bus and using a Cloud Config Server. The configuration or .properties or .yml files are "externalized" from the Spring app and instead retrieved from a Spring Cloud Config Server that the app connects to on startup. That Cloud Config Server retrieves the appropriate configuration .properties or .yml files from a GIT repo (there are other storage solutions, but GIT is the most common). You can then change configuration at runtime by changing the contents of the GIT repo's configuration files--The Cloud Config Server broadcasts the changes to any Client Spring applications via the Spring Cloud Bus, and those applications' configuration is updated without needing a restart of the app. You can find a working simple example here: https://github.com/ldojo/spring-cloud-config-examples

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