Develop Reference

How can I externalize some config variables in spring boot?

I have a yaml file that contains some credentials for azure keyvault. This project is I am working on is a shared git repo so I would like to set these values as environment variables for the whole project not just for myself
application.yml:
azure:
keyvault:
uri:someUri
client-id:someClientId
client-key:someClientKey
but I want to have them set up like this:
azure:
keyvault:
uri: ${uri}
client-id:${clientId}
client-key:${clientKey}
Is there a way to set those values and have this work for others without them having to manually set these values in their environment?

You can ignore the .yaml in gitignore so you can use your config in your environment. And if you pull from others their config won't overwrite your config.
If you want if like dynamically
java -jar myapp.jar --spring.application.json='{"foo":"bar"}'
You can add variables like this in start command. Configure in your Run configuration.

The syntax you've presented above is supposed to work.
I usually use capital letters for 'convention' but other than that its fine.
However providing such a syntax effectively means that you don't want to define property values in your application so you'll have to get them from elsewhere.
From your question I understand is that your primary concern is your teammates and in your setup each one of your peers has clientId, key, etc.
In this case you can create a script that will "export" all the variables to be environment variables automatically, they'll run it only one time and it will work since than.
Another option which is kind of similar is providing a property SPRING_APPLICATION_JSON that will refer to the json with a configuration, spring boot application can read it as written in the official documentation

How to know which environmental variables that are used in spring?

Lets say I have a large multi module java spring project in IntelliJ and I would like to see which database it run towards. How would I do this easily?
More generally it would be nice with an intellij plugin or feature that could show all the environmental variables that are used when for example running a test. I would like to be able to see an overview about which beans are being used, which environmental variables and which settings in various application.* files are being used for this particular execution. Is there such a feature or plugin in IntelliJ or any other way to do it?

There is many way to do this, but I think the simplest is by adding Spring Actuator to your project. You'll be able to show all created beans and environments variables via exposed endpoints (/beans, /env,..).

java.util.Properties ignoring ${...} placeholders

Anyone happen to come come across a use case where one has to stick to java.util.Properties.load method to read all the key-value pairs from a .properties file but at the same time to be environment/profile specific, placeholders, ${...} are used?
I'm building a spring boot app. and have profile specific properties files and placeholders work fine in them. However, the app. is dependent on a relatively older app that reads a property file from java.util.Properties.load method and in doing so the placeholders are being ignored. Since this is an old app. and do not want to change at this point in time, anyone has any suggestions on how do I go about?

If you're using Maven, you can write a generic properties file as such:
prop.1=${val1}
prop.2=${val2}
...
Then using the Filtering feature of the Maven Resources Plugin, you can do the replace your placeholders depdending on your maven profile.

Configure hibernate to use "show-sql=false" temporarily

I have a java progam using Maven, JPA, Eclipse, Jenkins. While developing I have the setting
spring:
jpa:
show-sql: true
in my application.yml file which works fine. Now, for a load test I have huge chunk of data. If I execute the test it works fine in Eclipse, but fails in Maven as the SureFire Plugin fails on such large console output. I can make it work by redirecting the console to a file, but that won't work for Jenkins and it won't work if I start the tests altogether because I want to see the result on the console obviously. So I would like to have this setting (show-sql) be switched off temporarily. I suppose it must live somewhere in the JPA / Hibernate configuration classes, but I couldn't find any combination yet that would allow me to change it.
Any advise is appreciated,
Stephan
The closest I suppose I came to it was by this:
entityManager.setProperty( "hibernate.show_sql", false );
entityManager.setProperty( "spring.jpa.hibernate.show_sql", false );
entityManager.setProperty( "javax.persistence.hibernate.show_sql", false );
Where the entityManager is autowired to the component. But when reading those properties, the return is some values from a completely different namespace (some timeout values), so I reckon I am in the wrong corner...

I assume you are also using spring, what you can do is using profiles which is available since version 3. See this link for more information: Spring Profiles. You can active profiles during runtime. For example in application-loadtest.yml would then be your configuration for your loadtests.
Or as alternative you can add this properties as parameter environment variables or as command line argument: Externalized configuration
I hope this helps.
regards, WiPu

How to Use Different META-INF/context.xml Files For Development and Production Environments

In Tomcat (and some other servlet containers) I can store information about my JDBC DataSource in META-INF/context.xml. This is very useful.
However, the settings for my JDBC DataSource can be different in my development and production environments. I'd like to know how other people deal with these differences in an elegant way, specifically how can I set up a context.xml for my development environment and one for my production environment in the most hassle-free manner.

You can create different files for specific builds. For example, create:
development.context.xml
production.context.xml
Then, you can control which context file is used in your build.xml file. Basically, setup a prompt for which type of build you would like to use. When you select development, it uses the development context file. When you select production, it uses the production context file.

I would do the same as Kevin mentioned. If you're using Maven you would use "profiles".

If you want to learn more about Maven profiles read this: Introduction to Build Profiles

Personally I wouldn't store configuration information like that in context.xml (perhaps in another properties file or something), but the general way for something like this is to have your build script package different versions of the configuration file into the WAR/EAR/whatever. You could have your build script decide whether to use the "dev" or "production" configuration file based on parameters you pass in, running different targets, etc.
Something I use often is the task in ant to replace certain tokens in files with values from a filters file; and swap which filters file is used depending on which environment I am targeting.