Spring Config Server – (search paths)

in the previous post sprig config server we have seen how to start a spring config server with a sample application config.

Let us see some more variations that spring allows us with spring config server.

The spring config server allows for using placeholders {application} and {profile} .

With this flexibility we can configure one repository per application against one repository for all the applications as we did in the previous post, let us see how. We will change what we did in earlier post so I will make changes to the same project to demonstrate the feature.

Let us first create two repositories for two applications “my-app-1” and “my-app-2”

Below I have created and initialized the first repo

add two files into this directory as application.yml and application-dev.yml

application.yml

app:
 name: my-app-1

application-dev.yml

app:
 name: my-app-1-dev

commit this file into the git repo with “git add .” and “git commit”

Now, similarity create another repo in the same root directory with name “my-app-2”, in my case it was “C:\Users\<user>\git”

So we have two repositories for the two apps now, one with name “my-app-1” and another with “my-app-2”. Now lets add this config to the server application config.

Navigate to the configuration of the config-server and update the git url to use application placeholder like below.

spring:
  application:
    name: my-config-server
  cloud:
    config:
      server:
        git:
          uri: file://c://Users/<user>/git/{application}

Now lets start the config server and see the application in action
browse the url – http://localhost:8001/my-app-1/dev to view dev profile and http://localhost:8001/my-app-1/master to view the master or the default profile. Similarly you can use http://localhost:8001/my-app-2/dev or http://localhost:8001/my-app-2/master for the “my-app-2” config.

With the placeholder “{profile}” we can also create various other combinations. For e.g. we can create directories within the application repo for each of different profile instead of the suffix used in our example or in case of single repository for all the applications, we can use profile for dev and test or any folder of your choice within the repository.

You can also use the placeholder {application} or {profile} in searchpath config which basically is instruction to the spring config server on the whereabouts of your app config.

I have created two directories under the single repository configuration from my previous post and instead of having the config with the app name into the root directory, now I have created 2 directories for each app within the same root directory like below

I will have to also update the config-server application configuration to instruct on this new application locations.

spring:
  application:
    name: my-config-server
  cloud:
    config:
      server:
        git:
          uri: file://c://Users/<user>/git/app-config
          searchPaths: '{application}'


server:
  port: 8001

Now restart the server and browse urls – “http://localhost:8001/my-app-1/master&#8221; or “http://localhost:8001/my-app-2/master&#8221; or their dev profiles. You should be able to see the change consistent with the expectations. Spring config server will now pull the configuration from the application directories.

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Spring Config Server

Spring config server is one of the very important module of spring cloud to basically externalize application configuration. In a microservice architecture, spring config server provides a central place where all the microservices can look for the application configuration. It has support for multiple applications and environments.

We will look into a sample spring server application supported by git as storage for the application config. Although we can use a different form of storage but then it will require some additional changes.

Navigate to spring https://start.spring.io/ and add config server to dependencies, provide the artifact details as per the screenshot below or choose one of your own and click on generate

This will download a zip to you local filesystem. Unzip the directory and import/open the project into your favorite IDE. I am using Intellij.

The imported project will look like below.

Take a look at the pom.xml, it will have dependency for spring cloud config server apart from the spring boot starter dependency. Also it will import spring cloud dependencies using the maven import pom.

<dependency>
 <groupId>org.springframework.cloud</groupId>
 <artifactId>spring-cloud-config-server</artifactId>
</dependency>

delete the application.properties file and create application.yml instead. Set the application name and set the server port to 8001 as below

spring:
  application:
    name: my-config-server

server:
  port: 8001

let us create a git repository on our local and then migrate it on to the github.

create a directory app-config and navigate into the directory on command line and fire command “git init”

create a file inside the app-config directory. lets say myapp.yml and add a property like below

app:
 name: my-first-app

Now add this file to the git repo using git add and then git commit as below

let us add reference to this repo in our spring boot application. To do this, just open the application.yml file use the spring.cloud.config.git.url to the repository we created like below

spring:
  application:
    name: my-config-server
  cloud:
    config:
      server:
        git:
          uri: file://c://Users/Amey/git/app-config

Now to initialize our spring boot application as config server, we have to add the annotation @EnableConfigServer to our main class like below

@SpringBootApplication
@EnableConfigServer
public class MyConfigServerApplication {
	public static void main(String[] args) {
		SpringApplication.run(MyConfigServerApplication.class, args);
	}

}

Now we are ready to run the spring config server application. Right click on the class and run the application.

Now on the browser, navigate to the url “http://localhost:8001/my-first-app/master&#8221; to see spring config server responding as below

Here the spring has assumed the default profile as master or assumed that the branch is the default profile.

Now lets add another file to the git repo with name “my-first-app-dev.yml” and add the following property to the config

app:
 name: my-first-app-dev

lets go back to the browser and now instead of master lets use dev as the profile in the url and check what the server responds with ( “ http://localhost:8001/my-first-app/dev“) .

Now our spring config server has done the magic trick. It has returned us the dev profile for our application. if you see the app.name is now my-first-app-dev and also we did not restart the server. Spring has picked up the change and responded with new profile we just added.

In the next blog, we will see various other configurations that we can use with spring config server.