Develop Reference

The best way to make app configs editable for docker image/container?

I have an app which is dockerized like this:
FROM openjdk:11-jre-slim as jdkbase
FROM jdkbase
COPY target/dependency-jars /run/dependency-jars
COPY target/resources /run/resources
ADD target/app-1.0.2.jar /run/app-1.0.2.jar
CMD java -jar run/app-1.0.2.jar
This app uses some configs from application.properties. I push this docker image into my private registry for using it inside Kubernetes cluster.
There is no problems unless i have to change any properties in application.properties. Lets say, my database URL was changed. So, I have to undate it in application.properties and then force my app to use updated configs. I've tried to edit application.properties inside the running docker container and then restart the container. As a result, after i restart my container it has edited application.properties BUT the app still uses old URL.
The only way i've found to force the app to use new configs is to commit changed container into new image and then start the new image.
It works, but it doesn't seems to me to be an optimal solution: like, after every changes in app's configs I have to recreate image, which is +300Mb of data, I have to push this new image into registry, I have to recreate Kubernetes pod from new image... It looks like too much unnecessary actions to just change one URL.
So, is there any other more optimal way to work with needs to change application.properties from time to time?

If this is a spring boot application is easy to define a variable as an environment variable. If an environment variable is present it overwrite the variable with the same name defined in your application.properties.
What happens is called externalized configuration and it is defined here :
Spring Boot allows you to externalize your configuration so you can work with the same application code in different environments. You can use properties files, YAML files, environment variables and command-line arguments to externalize configuration. Property values can be injected directly into your beans using the #Value annotation, accessed via Spring’s Environment abstraction or bound to structured objects via #ConfigurationProperties.
Spring Boot uses a very particular PropertySource order that is designed to allow sensible overriding of values. Properties are considered in the following order:
Devtools global settings properties on your home directory (~/.spring-boot-devtools.properties when devtools is active).
#TestPropertySource annotations on your tests.
#SpringBootTest#properties annotation attribute on your tests.
Command line arguments.
Properties from SPRING_APPLICATION_JSON (inline JSON embedded in an environment variable or system property)
ServletConfig init parameters.
ServletContext init parameters.
JNDI attributes from java:comp/env.
Java System properties (System.getProperties()).
OS environment variables.
A RandomValuePropertySource that only has properties in random.*.
Profile-specific application properties outside of your packaged jar (application-{profile}.properties and YAML variants)
Profile-specific application properties packaged inside your jar (application-{profile}.properties and YAML variants)
Application properties outside of your packaged jar (application.properties and YAML variants).
Application properties packaged inside your jar (application.properties and YAML variants).
#PropertySource annotations on your #Configuration classes.
Default properties (specified using SpringApplication.setDefaultProperties).
So you can pass at runtime an environment variable to your docker to solve this problem. You don't need to recreate the Docker image each time.

Directory for Spring boot additional location parameter

I am trying override few of the properties in my spring boot application. The properties are spread across mutiple yml files within the same directory and hence i would like to specify spring.config.additional-location parameter with the value of directory..
spring.config.additional-location=file:///Mydirectory/
But the application is not able to load the configs. If I explicitly specify the file name, the properties are getting overwritten
spring.config.additional-location=file:///Mydirectory/application.yml
Is it possible to load all the files available in a directory using spring.config.additional-location? If yes, please let me know

Read active application.properties from jar - injected by maven

I want to read Spring's boot active application.properties file a jar file that I add as Maven dependency.
We mange environment params via 3-4 files under publish folder, for example:
-publish
--some.project-application.properties.test
--some.project-application.properties.dev
in the project root so I cannot use PropertySources(different file name per env).
So is there is a way to read the active(in use) application.properties file?
Is using #Value annotation will work without any configuration?

I think you should use spring naming conventions(application.properties, application-dev.properties), so that spring will automatically take the correct property file from the class path.
Also, refer : How to resolve placeholder in properties file with values from another properties file in spring boot application

Spring Boot/Maven property and system temp folder path

I have a following property declared at my Spring Boot/Maven project:
#Value("${download.folder.path}")
private String downloadFolderPath;
where download.folder.path is a property declared at my application.properties file and at Maven profile.
Right now the property value is something like this:
<download.folder.path>d:/somedir</download.folder.path>
Everything works fine but I want to point download.folder.path property to default system temp folder for my tests instead of providing a real path.
Is it possible with Spring/Maven configuration?

Use reference to java tmp dir property (check System.getProperty("java.io.tmpdir")) and reference the property like this
<download.folder.path>{java.io.tmpdir}</download.folder.path>
See the reference properties here

If you are using Spring Boot, check out #TestPropertySource.
https://docs.spring.io/spring/docs/current/spring-framework-reference/html/integration-testing.html#__testpropertysource
You should be able to use that to point to /tmp or wherever.

1.)Writing below in SpringBoot main class for whole application to be working :
System.setProperty("java.io.tmpdir", "C:\\Users\\abcde\\Desktop\\Temp");
2.)While Running JUnit in Spring Boot application , I have set -Djava.io.tmpdir=C:\Work\TEMP in VM Arguments and it worked for me .

Spring boot external configuration of property file

I have a spring boot application that I can package in a war that I want to deploy to different environments. To automate this deployment it'd be easier to have the configuration file externalized.
Currently everything works fine with a application.properties file in src/main/resources. Then I use ´mvn install´ to build a war deployable to tomcat.
But I would like to use a .yml file that does not need to be present on mvn install but that would be read from during deployment of the war and is in the same or a directory relative to my war.
24. externalized configuration shows where spring boot will look for files and 72.3 Change the location of external properties of an application gives more detail on how to configure this but I just do not understand how to translate this to my code.
My application class looks like this:
package be.ugent.lca;
Updated below
Do I need to add a #PropertySource to this file? How would I refer to a certain relative path?
I feel like it's probably documented in there as most spring boot documentation but I just don't understand how they mean me to do this.
EDIT
Not sure if this should be a separate issue but I think it's still related.
Upon setting the os variable the error of yaml file not found went away. Yet I still get the same error again as when I had no application .properties or .yml file.
Application now looks like this:
#Configuration
**#PropertySource("file:${application_home}/application.yml")**
#ComponentScan({"be.ugent.lca","be.ugent.sherpa.configuration"})
#EnableAutoConfiguration
#EnableSpringDataWebSupport
public class Application extends SpringBootServletInitializer{
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
The application_home OS variable
$ echo $application_home
C:\Masterproef\clones\la15-lca-web\rest-service\target
My application.yml file(part it complains about):
sherpa:
package:
base: be.ugent.lca
Error upon java -jar *.war
All variations upon:
Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'sherpa.package.base' in string value "${sherpa.package.base}"
at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:174)
at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:126)
at org.springframework.core.env.AbstractPropertyResolver.doResolvePlaceholders(AbstractPropertyResolver.java:204)
at org.springframework.core.env.AbstractPropertyResolver.resolveRequiredPlaceholders(AbstractPropertyResolver.java:178)
at org.springframework.context.support.PropertySourcesPlaceholderConfigurer$2.resolveStringValue(PropertySourcesPlaceholderConfigurer.java:172)
at org.springframework.beans.factory.support.AbstractBeanFactory.resolveEmbeddedValue(AbstractBeanFactory.java:808)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1027)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1014)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:545)
... 142 more

Using external properties files
The answer lies in the Spring Boot Docs, I'll try to break it down for you.
First of all, no you should not use #PropertySource when working with Yaml configuration, as mentioned here under the Yaml shortcomings :
YAML files can’t be loaded via the #PropertySource annotation. So in the case that you need to load values that way, you need to use a properties file.
So, how to load propery files? That is explained here Application Property Files
One is loaded for you: application.yml , place it in one of the directories as mentioned in the link above. This is great for your general configuration.
Now for your environment specific configuration (and stuff like passwords) you want to use external property files, how to do that is also explained in that section :
If you don’t like application.properties as the configuration file name you can switch to another by specifying a spring.config.name environment property. You can also refer to an explicit location using the spring.config.location environment property (comma-separated list of directory locations, or file paths).
So you use the spring.config.location environment property.
Imagine you have an external config file: application-external.yml in the conf/ dir under your home directory, just add it like this:
-Dspring.config.location=file:${home}/conf/application-external.yml as a startup parameter of your JVM.
If you have multiple files, just seperate them with a comma. Note that you can easily use external properties like this to overwrite properties, not just add them.
I would advice to test this by getting your application to work with just your internal application.yml file , and then overwrite a (test) property in your external properties file and log the value of it somewhere.
Bind Yaml properties to objects
When working with Yaml properties I usually load them with #ConfigurationProperties, which is great when working with for example lists or a more complex property structure. (Which is why you should use Yaml properties, for straightforward properties you are maybe better of using regular property files). Read this for more information: Type-Safe Configuration properties
Extra: loading these properties in IntelliJ, Maven and JUnit tests
Sometimes you want to load these properties in your maven builds or when performing tests. Or just for local development with your IDE
If you use IntelliJ for development you can easily add this by adding it to your Tomcat Run Configuration : "Run" -> "Edit Configurations" , select your run configuration under "Tomcat Server" , check the Server tab and add it under "VM Options".
To use external configuration files in your Maven build : configure the maven surefire plugin like this in your pom.xml:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<configuration>
<argLine>-Dspring.config.location=file:${home}/conf/application-external.yml</argLine>
</configuration>
</plugin>
When running JUnit tests in IntelliJ:
Run → Edit Configurations
Defaults → JUnit
add VM Options -> -ea -Dspring.config.location=file:${home}/conf/application-external.yml

Yes, you need to use #PropertySource as shown below.
The important point here is that you need to provide the application_home property (or choose any other name) as OS environment variable or System property or you can pass as a command line argument while launching Spring boot. This property tells where the configuration file (.properties or .yaml) is exactly located (example: /usr/local/my_project/ etc..)
#Configuration
#PropertySource("file:${application_home}config.properties")//or specify yaml file
#ComponentScan({"be.ugent.lca","be.ugent.sherpa.configuration"})
#EnableAutoConfiguration
#EnableSpringDataWebSupport
public class Application extends SpringBootServletInitializer{
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}

There is a very simple way to achieve this.
Inside your original application.properties file you can just specify the following line:
spring.config.import=file:Directory_To_The_File/Property_Name.properties
It will automatically sync all the properties from the external property file.
Now lets say that you have a situation where you need to get properties from multiple property files. In that case, you can mention the same line in the external property file which in turn will take the remaining properties from the second property file and so on.
Consider the following example.
application.properties:
spring.config.import=file:Resources/Custom1.properties
Custom1.properties:
server.port=8090
.
.
.
spring.config.import=file:Resources/Custom2.properties

One of the easiest way to use externalized property file using system environment variable is, in application.properties file you can use following syntax:
spring.datasource.url = ${OPENSHIFT_MYSQL_DB_HOST}:${OPENSHIFT_MYSQL_DB_PORT}/"nameofDB"
spring.datasource.username = ${OPENSHIFT_MYSQL_DB_USERNAME}
spring.datasource.password = ${OPENSHIFT_MYSQL_DB_PORT}
Now, declare above used environment variables,
export OPENSHIFT_MYSQL_DB_HOST="jdbc:mysql://localhost"
export OPENSHIFT_MYSQL_DB_PORT="3306"
export OPENSHIFT_MYSQL_DB_USERNAME="root"
export OPENSHIFT_MYSQL_DB_PASSWORD="123asd"
This way you can use different value for same variable in different environments.

Use below code in your boot class:
#PropertySource({"classpath:omnicell-health.properties"})
use below code in your controller:
#Autowired
private Environment env;