How to use environment variables on a Spring Boot and Gradle application? - java

I explain my problem;
I have a web app developed using Vue.js and Spring Boot, this application working a PDF sheet and saves the file that is generated by Java, I use two lines of code to separate my development part from the production part (I leave you the 2 lines of code like this you understand the concept well)
FileReader leggoFile = new FileReader(System.getProperty("user.dir") + "/temp/webapps/foolder/foolder/file.pdf");
// FileReader leggoFile = new FileReader(System.getProperty("catalina.base") + "/temp/webapps/foolder/foolder/file.pdf");
This whole application is built using the "bootWar gradle plugin" which returns me a .war which I will then upload to a Tomcat server;
My goal is this:
I would like to set a single environment variable so that if I want to build the project I don't have to comment/uncomment that line for example:
FileReader leggoFile = new FileReader({{variableEnvironment}} + "/temp/webapps/foolder/foolder/file.pdf")
my question is this:
How dp Gradle and Spring Boot handle environments? Is there a way to separate environments? Is this possible or should I start thinking differently?
I tried to search on something but unfortunately I was tied to the problem that I don't understand how the .war file is generated through the BootWar Gradle plugin, also searching on the internet I understood that environment Gradle and environment Spring are two separate things but in general even if I know the line of code is wrong in the beginning my question is always the same:
How are environment variables handled in Spring and Gradle?

With Spring Boot, you can add properties to your application by adding an file named application.yaml to your resources folder (src/resources/). In addition you can add properties through application-{profile}.yaml to add properties only for given Spring profiles. For instance application-test.yaml would only be read if "test" is an active profile. When booting up the application, Spring will first read application.yaml, then any profile-specific YAML-files, such that any overlapping properties are replaced.
There are several approaches to injecting the property. A simple solution is to add a field to your component annotated with #Value("${PATH}) and replace PATH with the property's path in the YAML.

Related

PropertiesLauncher command line arguments not working with Spring Boot executable Jar

So I have basic multi-module Spring Boot project. The goal, that I had was to build executable jar and pass additional properties with the help of -Dloader.path=....
For some reason (if I understand purpose of this argument) loader.path is being ignored completely.
My project structure is following:
\-
|--conf
|---default
|--pets-api
|--pets-app (this module contains the Main-Class)
|--pets-domain
|--pets-infrastructure
Since no custom active profile is being passed it uses "default". Jar contains application-default.propeties file, that has single configuration server.servlet.context-path=/v1.
/conf/default location has 2 properties files:
application.properties
random.properties - this is bind to #ConfigurationProperties(prefix = "...") inside application
When I run it normally everything is fine java -jar pets-app-0.0.1-SNAPSHOT.jar. It just uses application-default.properties file and that is it.
Now when I am trying to utilize -Dloader.path argument as in java -Dloader.path=PATH/TO/conf/default -jar pets-app-0.0.1-SNAPSHOT.jar it starts application same as before, as if I am not adding 2 more file to classpath.
What is used:
Java 17
Spring Boot 2.6.12
Gradle
Did anyone come across this as well? Any suggestion on how to resolve it?
PS. If there is need to see the code, I can upload it to GitHub.

Java MVC project in Spring Tool Suite additional files

I'm learning to make Java MVC project using Spring Tool Suite tool.
The path to make new project is:
File->New->SpringLegacyProject->Spring MVC Project.
My question is: which directory I have to use to add additional not-Spring files and where and what do I have to type for Spring files to see them?
For example:
css files - where to put and how to make jsp views see them, will 'link rel="" 'tag be enough?
properties files used to specify database connection or to specify messages for ReloadableResourceBundleMessageSource. In this case, do I have to create bean for this class in root-context.xml?
Thanks.
You should probably use Spring Boot (i.e. use File->New->Spring Starter Project and select Web as a starter. Place your web resources under src/main/resources/static folder. They are picked up automatically from that folder.
You should try an example project: File -> New -> Import Spring Getting Started Content and then pick "Serving Web Content" from the list.
Try some DB getting started content example to get the answer for the second part of your question.

Need in understanding classpath in resource location and variable value set

Although I have been working in java for a while, there are many small things I have been ignoring, which at times have become bottleneck in productivity. I have difficulty in understanding this:
This is one of the bean.xml which gets placed in the final .war file (in a web application, built with spring framework).
<context:property-placeholder
location="classpath:/${deploy.env}/com.example.config/db.properties"
ignore-resource-not-found="false" />
I have following doubts:
1) At the time of building the code, i did like this for passing value of deploy.env
mvn clean install -Ddeploy.env=local
I ran the mvn in debug mode and could see this set to local. Now, the thing is, in the .war that gets generated, it is still ${deploy.env} (see above snippet). Doesn't this get replaced in the final .war? If not, then how do we pass the value which we intend to set?
2) what does "classpath:/${deploy.env}/com.example.config/db.properties" mean? Who sets the value of classpath? Are classpath capable of providing the location of resource files as well?
Assuming deploy.set --> local, so would this get translated to:
classpath:"/local/com.example.config/db.properties"
So does this mean db.properties would be present at: /local/com.example.config/db.properties
Any inputs to understand this would be of great help.
deploy.env is either environment variable or system property available to the JVM at run time.
The classpath:/${deploy.env}/com.example.config/db.properties will be resolved at run when your war is running in the container.
Set deploy.env=whatever in the shell from where you starting the tomcat or set in the environment of the user which starts the tomcat.
mvn clean install -Ddeploy.env=local here the deploy.env system property is available at build time. This will not replace the value of your spring config.
classpath is where all your classes and libraries bundled in the war are available along with the tomcat libraries. The spring property configurer will look for the db.properties file in the classpath at location e.g. /local/com.example.config
Spring documentation to learn more
Some explanation on my blog post
As stated in the Oracle Web site: The CLASSPATH variable is one way to tell applications, including the JDK tools, where to look for user classes.
That classpath: is referring to that location in particular, whatever it is, so it will start looking for those resources defined by Spring from that location and on, until it finds the first match.
Also, if you have that as a property in Maven, the value can be replaced with the right plug-in and configuration; not quite useful when you want a build that can be used with many values within those .properties files for different environments.
You can use other prefixes as file:, http:, etcetera. But you are just wondering about classpath:.

play 2.4.x current application environment

Is there any function to return the current working environment of a Play framework application ?
I tried the following but it doesn't seem to be working correctly;
String environment = play.api.Play.Mode
NOTE: I don't want to use isDev() isProd() stuff, I want to be able to create custom environments
PlayFramework 2.x supports only 3 modes: Prod, Dev and Test. First is used for production. Second provides more development additions like hotloading just editet classes. The last one is like the second one but with test libraries.
Play 1.x had also ID, which was able for using as different environment. For instance staging or instance of distributed server.
Play 2.x sadly doesn't support ID's anymore. But You can achieve the same effects manually.
Suppose you want to run your application in 'staging' mode.
First you need put configuration file along with basic configuration file, but named as application.staging.conf.
Second step is add to Global.scala code responsible for managing configuration files, something like this:
import java.io.File
import play.api._
import com.typesafe.config.ConfigFactory
object Global extends GlobalSettings {
override def onLoadConfig(config: Configuration, path: File, classloader: ClassLoader, mode: Mode.Mode): Configuration = {
val env = System.getProperty("environment")
val envConfig = config ++ Configuration(ConfigFactory.load(s"application.${environment}.conf"))
super.onLoadConfig(environmentSpecificConfig, path, classloader, mode)
}
}
As you see it reads environment value and look at specific configuration file.
The last step is telling play framework which mode it should use. The best way is by starting command:
activator run -Denvironment=staging
Should works.
In Java it is play.Application.isDev() and isProd() or isTest()
https://playframework.com/documentation/2.2.x/api/java/index.html

Play Framework - How to keep the configurations of my module inside it?

I am using Play Framework 2.2.x/Java.
I want to create a module to sperate some of the logics from my main application and also I want to use the application.conf inside the module for its configurations instead of using the main application's config file!
But using the following snippet in the module, only reads values from the main application config file:
Play.application().configuration().getString("myVar");
Is there any other way to get the values from the application.conf file inside my module?
Play uses the typesafe-config library for reading configuration. This is actually a Java library, even though Typesafe is a Scala company.
The documentation for typesafe-config says "The idea is that libraries and frameworks should ship with a reference.conf in their jar."
So your module's config should be stored in a file called reference.conf - the format is exactly the same, it's just the name that is different.
The problem occurs because there is a conflict between the two config files because they are named the same, so it probably goes by classpath order or something. Don't use two application.conf files - this problem has bitten me in the past!
Save your config into ie. /conf/my-module.conf of the main app and then include it at the end of application.conf like:
include "my-module.conf"

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