How to make Spring Boot skipping some configurations - spring-boot

I have a Spring-Boot project which works with DB-connections and a lot of other stuff.
Now I added another "main-class" to the project. The thing is: by starting this class, all configuration settings (which come from application.yml) are loaded. But thats not what I want.
I want the project to start without trying to bind to any datasource...
But how?

Why do you add several main classes? Try using different profiles instead. And you can start your application with the -Dspring.profiles.active=? property.
Example:
Just add a application-test.properties and run your application with -Dspring-profiles.active=test and the properties in the test property file will be loaded. And potentially overwrite properties with the same key in application.properties.

Related

Moved my spring boot application from mullti module to zero module and application.properties is not detected on IntelliJ IDEA

My application has a lot of modules, namely
entity
dto
rest-web
After removing all the module and combining the application like the default template in https://start.spring.io/, my application can start but it didn't recognize application.properties even though I have put the properties there.
Make sure that the parent pom.xml file does not have <packaging>pom<packaging>, otherwise the IDE wont recognize the spring application correctly

Spring Boot #Value Properties Report

I have an Spring Boot application, which has a number of properties and is delivered to an "external" customer.
Most properties have sane defaults, so they are added to application.properties and one can identify them there.
But there are also some properties which do not have a sane default, they must be defined by the external customer, thus they are currently included in application.properties with a dummy-value (to-be-replaced), but it's easy to miss such a property and Spring will not complain the property missing but trying to load it, which sometimes (hostnames, ...) leads to unexpected results.
The project is built with Maven -- is there maybe a way already a way to scan the project during build for all #Value() annotations and generate some kind of report?
Then the devs could define those values-without-default simply using #Value, the report will show them as having no default and one thus knows which properties are necessary to set.

Is there a way to generate application properties when creating a Spring Boot project?

I'm planning to run our own Spring Initializr instance. Is there a way to have a set of application properties get written (to application.yml) when a certain option is chosen, ideally in a separate section for each of a set of predefined profiles? I've looked into customising the project-generation process in Initializr and at creating a custom starter. I've come across auto-configuration for starters, but that seems to be about what configuration to default to when this has not been provided by properties, whereas I am after generating the properties. I've also come across an example of a custom Spring Initializr instance generating files, but I need it to modify application.yml without clobbering any other modifications that may have been made to it.
Spring Initializr (the library behind start.spring.io) does not have yaml support and does not allow you to write such file automatically when the project is generated.
It's easy enough for you to add that feature though. The way it works is through a model that contributors would tune + a writer that transform the model into the target output. An analogy of this would be MavenBuild and MavenBuildWriter that generates Maven's pom.xml.
Auto-configuration is indeed completely unrelated to code/configuration generation so no need to look there.

Simplifying deployment configs for SpringMVC project

We've multi module SpringMVC project, each having separate applicationContext.xml, currently we have to edit the applicationContext.xml files for every module before we deploy. It's painful and error prone. Is there a way to have only one property file that all other will contexts look at. Then we only have to edit one property file before we build and deploy. Thanks in advance.
It sounds like you should be using Spring's Profile support, which allows you to specify separate properties files per environment. You can pass the application an environment property spring.profiles.active and set it to say, "dev", "test", or "prod".
If you're using Spring Boot it can then automatically pick up distinct configuration per environment, application.dev.properties or application.prod.properties which will overwrite the standard application.properties with environment specific configuration.
If not using Spring Boot you would just have configure your Properties Sources per profile.
This is most definitely the preferred approach to changing configuration files at build or deploy time.
Reference: http://docs.spring.io/spring/docs/current/spring-framework-reference/htmlsingle/#beans-environment

Spring boot application.properties maven multi-module projects

We are using spring boot in a multi-module project.
We have a Domain access module which has the common domain object classes, repositories, together with configuration for the datasource, JPA, Hibernate, etc. These are configured using a application.properties. We put all this configuration into the common module to save duplicating these common configurations in the higher level modules.
This all works fine when building the domain module, so the configurations are loaded correctly in the test units.
However the problems start when we try to use the domain module in the higher layer modules; they have their own application.properties which means Spring loads them and not the the Domain module application.properties, which this means the data source is not configured because only the higher module application.properties are loaded.
What we would like is both the domain module and higher level application properties to be loaded by Spring. But we can't see any easy way to do this.
I'm thinking this must be a common problem, and wonder if there any recommended solutions for this problem?
As we are using spring-boot the solution should ideally use annotations instead of applictionContext.xml.
Maybe you should only use application.properties in the top-level aggregator project?
You can always use #PropertySource in the child projects to configure them with a name that is specific to their use case.
Or you can use different names for each project and glue them together in the top-level project using spring.config.location (comma-separated).
I agree with #Dave Syer. The idea of splitting an application into multiple modules is that each of those is an independent unit, in this case a jar file. Theoretically you could split each of those jar files into their own source repositories, and then use them across multiple projects. Let's say you want to reuse these domain classes in both a web and batch application, if all the APPLICATION level configuration is stored within each of the individual modules, it severely reduces their reusability.
IMO only the aggregating module should contain all of the configuration necessary to run as an application, everything else is simply a dependency that can be remixed and reused as necessary.
Maybe another approach could be to define specific profiles for each module and use the application.properties file just to specify which profiles are active
using the spring.profiles.include property.
domain-module
- application.properties
- application-domain.properties
app-module
- application.properties
- application-app.properties
and into the application.properties file of app-module
spring.profiles.include=domain,app
Another thing you can do (besides only using application.properties at the top-level as Dave Syer mentions) is to name the properties file of the domain module something like domainConfig.properties.
That way you avoid the name clash with application.properties.
domainConfig.properties would contain all the data needed for the domain module to be able to tested on it's own. The integration with the rest of the code can easily be done either using multiple #PropertySource (one for domainConfig.properties and one for application.properties) or configuring a PropertySourcesPlaceholderConfigurer bean in your Java Config (check out this tutorial) that refers to all the needed property files
in spring-boot since 2.4 support spring.config.import
e.g
application.name=myapp
spring.config.import=developer.properties
# import from other module
spring.config.import=classpath:application-common.properties
or with spring.config.activate.on-profile
spring.config.activate.on-profile=prod
spring.config.import=prod.properties
ref: https://spring.io/blog/2020/08/14/config-file-processing-in-spring-boot-2-4

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