Category: Container

Spring boot Cloud Native Buildpacks and Layered jars.

In May 2020 spring boot 2.3 is released with some interesting features. There are many but in this article, we will talk about support for building OCI images using cloud-native build packs. 

Cloud-Native BuildPacks?

These days cloud migration and in that cloud-native application development is becoming a trend.

Cloud-Native Buildpacks
transform your application source code to images that can run on any cloud.

Cloud-native buildpacks definition from From https://buildpacks.io/,

The Cloud Native Buildpacks project was initiated by Pivotal and Heroku in January 2018 and joined the Cloud Native Sandbox in October 2018. The project aims to unify the buildpack ecosystems with a platform-to-buildpack contract that is well-defined and that incorporates learnings from maintaining production-grade buildpacks for years at both Pivotal and Heroku.

credit goes to https://buildpacks.io/

Cloud-Native Buildpacks embrace modern container standards, such as the OCI(Open container initiative) image format. They take advantage of the latest capabilities of these standards, such as cross-repository blob mounting and image layer “rebasing” on Docker API v2 registries.

All the above information is from buildpack website only. The buildpack in fewer words: will transform your beautiful source code into runnable container images.

The Paketo java build is used by default to create an image.

Prerequisites for this example:

  1. Java
  2. Docker
  3. Any IDE if you want.

Note:- For this demo, I am using spring-boot:2.3.1 version, JDK-8 and maven.

and Always for spring start with https://start.spring.io/

I have imported the project into the VSCode. If you want to learn about Spring tools for Visual Studio Code, please go through this link: https://www.techwasti.com/spring-tools-4-for-visual-studio-code/

Create One REST Controller:-

As part of this article, our focus is on buildpack not on complex coding.

We have a simple controller this will return the current date.

package com.techwasti.spring.buildpackex.springboot23ocibuildpackex;

import java.util.Date;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class CurrentDateController{


    @GetMapping("/gettodaysdate")
     public String getTodaysDate(){
        return new Date().toString();
     }
}

Output: Sun Jul 19 09:00:36 IST 2020

Build the image for our app:

As mentioned above and as per the spring boot documentation, we will build an image. Package the source code and build the image as per OCI standard using the maven task.

$ mvn spring-boot:build-image

When you fire this command everything will be taken by spring boot build-image task. After a successful building image.

In your log you will see similar logs:

Successfully built image ‘docker.io/library/spring-boot23-oci-buildpack-ex:0.0.1-SNAPSHOT’

We can validate our docker image using the below command.

$ docker images| grep spring

Output
spring-boot23-oci-buildpack-ex 0.0.1-SNAPSHOT ddabb93c2218 40 ago 231MB

Now our image is ready, let us run the image and create a container 

$ docker run -d -p 8080:8080  — name springbuildpackex spring-boot23-oci-buildpack-ex:0.0.1-SNAPSHOT

once a container ready verify using 

$ docker ps

Hit REST API endpoint http://localhost:8080/gettodaysdate

You can hit actuator endpoints 

http://localhost:8080/actuator/metrics

http://localhost:8080/actuator/info

Spring Boot 2.3.0.RC1 Paketo Java buildpack is used by default to create images.

you can check on your local docker when you fire below command you can see Paketo docker image was downloaded.

$ docker images| grep gcr
gcr.io/paketo-buildpacks/run       base-cnb                c8c8215efa6f        8 days ago          71.1MB
gcr.io/paketo-buildpacks/builder   base-platform-api-0.3   e49209451fa6        40 years ago        696MB

Customize build pack configuration:

Now we have seen that by default the name of the image is based on artifactId and a tag is a version of our maven project. Image name if spring-boot23-oci-buildpack-ex 0.0.1-SNAPSHOT

docker.io/library/${project.artifactId}:{project.version}

In your real-life project, you would like to push the OCI image to a specific docker image registry, which is internal to your organization. Here I am using the docker hub is a public central registry. You configure parameters such as the name of the docker image in POM.xml

<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<image>
<builder>docker.io/maheshwarligade/spring-boot23-oci-buildpack-ex</builder>
</image>
</configuration>
</plugin>

With these custom tags and names, I can push this image to the docker hub.

docker push docker.io/maheshwarligade/spring-boot23-oci-buildpack-ex

Using the command line as well:

$ mvn spring-boot:build-image -Dspring-boot.build-image.imageName=enterprise.com/library/domain/sspring-boot23-oci-buildpack-ex

We can also configure build packs builder to build the image using below configuration param

<configuration>            
<image>              
<builder>cloudfoundry/cnb</builder>            
</image>         
</configuration>

Proxy Configuration:

If any proxy is configured between the Docker daemon the builder runs in and network locations that build-packs download artifacts from, you will need to configure the builder to use the proxy. When using the default builder, this can be accomplished by setting the HTTPS_PROXY and/or HTTP_PROXY environment:

<configuration>      
 <image>       
  <env>        
    <HTTP_PROXY>http://proxy.example.com</HTTP_PROXY>                      <HTTPS_PROXY>https://proxy.example.com</HTTPS_PROXY>      
    </env>     
  </image> 
</configuration>

Layered Jars:

We have seen above to create the image we used to build-pack, but you might not want to use build pack to build an image, perhaps we want to use some tool which is used within your organization based docker file to create an application image, Spring wanted to make it also easier to create optimized Docker images that can be built with a regular dockerfile so Spring has added support for layered jars.

basically we follow approach to create a docker image using spring boot application fat jar and add that into docker file and add a command to execute this.

The jar is organized into three main parts:

  • Classes used to bootstrap jar loading
  • Your application classes in BOOT-INF/classes
  • Dependencies in BOOT-INF/lib

Since this format is unique to Spring Boot, In spring boot in 2.3.0.M1 providing a new layout type call LAYERED_JAR

As we know about the docker file its layered file and when we rebuild image for dev purpose it should build where changes had happened instead of rebuilding the fat jar layer again and again. The layered jar type is designed to separate code based on how likely it is to change between application builds. Library code is less likely to change between builds, so it is placed in its own layers to allow tooling to re-use the layers from the cache. Application code is more likely to change between builds so it is isolated in a separate layer.

  • dependencies (for regularly released dependencies)
  • snapshot-dependencies (for snapshot dependencies)
  • resources (for static resources)
  • application (for application classes and resources)

Build the docker file 

<build>
 <plugins>
  <plugin>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-maven-plugin</artifactId>
   <configuration>
    <layout>LAYERED_JAR</layout>
   </configuration>
  </plugin>
 </plugins>
</build>

Build jar for application

$ mvn clean package

We can have layered jar using jarmode

$ java -Djarmode=layertools -jar target/spring-boot23-oci-buildpack-ex-0.0.1-SNAPSHOT.jar list

Output

dependencies
snapshot-dependencies
resources
application

based on this we can craft docker file which will be similar like below:

FROM adoptopenjdk:11-jre-hotspot as builder
WORKDIR application
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} application.jar
RUN java -Djarmode=layertools -jar application.jar extract

FROM adoptopenjdk:11-jre-hotspot
WORKDIR application
COPY --from=builder application/dependencies/ ./
COPY --from=builder application/snapshot-dependencies/ ./
COPY --from=builder application/resources/ ./
COPY --from=builder application/application/ ./
ENTRYPOINT ["java", "org.springframework.boot.loader.JarLauncher"]

Summary:–

Here we have seen multiple ways to create an image of our spring boot application. With buildpacks, docker files, & existing plugins such as jib, there is no conclusion that which is the best way. Each approach has pros and cons and we have to use these tools based on our easiness and simplification.

Source Code: https://github.com/maheshwarLigade/spring-boot23-oci-buildpack-ex

References:

Micronaut with Graal native image example.

As we have seen in the last couple of articles on how to create simple Micronauts application development and dockerizing it. In this article, we are gone exploring Helloworld Graal micronaut application.

Here is the definition from Wikipedia. If you are crossing this article that means you are familiar with either of the topic.

GraalVM is a Java VM and JDK based on HotSpot/OpenJDK, implemented in Java. It supports additional programming languages and execution modes, like an ahead-of-time compilation of Java applications for fast startup and low memory footprint. The first production-ready version, GraalVM 19.0, was released in May 2019.

Let us start coding and simultaneously enjoy the topic.

Create a micronaut application using CLI:

$ mn create-app helloworld-graal --features=graal-native-image

The default option is not available to add Graal support we have to use this option  — features=graal-native-image.

If you are using Java or Kotlin and IntelliJ IDEA make sure you have enabled annotation processing.

Now let us create one simple POJO class to hold Play name to make it simple.

import io.micronaut.core.annotation.Introspected;

@Introspected
public class Play{

    private String name;

    public Play(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

@Introspected annotation is used to generate BeanIntrospection metadata at compilation time. This information is using the render the POJO as JSON using Jackson without using reflection.

Now let us create the Singelton Service class and return play name randomly.

(Note:- The play names are Marathi Play names of famous Sri Pu la Deshpande)

import javax.inject.Singleton;
import java.util.Arrays;
import java.util.List;
import java.util.Random;

@Singleton
public class PlayService {
// create list of plays
    private static final List<Play> PLAYS = Arrays.asList(
            new Play("Tujhe Ahe Tujpashi"),
            new Play("Sundar Mee Honar"),
            new Play("Tee Phularani"),
            new Play("Teen Paishacha Tamasha"),
            new Play("Ek Jhunj Varyashi")
    );
 // to choose random play from PLAYS list
    public Play randomPlay() {
        return PLAYS.get(new Random().nextInt(PLAYS.size()));
    }
}

Now we need a controller to serve the request of random play name from service class.

import io.micronaut.http.annotation.Controller;
import io.micronaut.http.annotation.Get;

@Controller
public class PlayController {

    private final PlayService playService;

    public PlayController(PlayService playService) {
        this.playService = playService;
    }

    @Get("/randomplay")
    public Play randomPlay() {
        return playService.randomPlay();
    }
}

Created controller and injected service object using constructor injection and mapping of GET method using @Get(“/randomplay”).

Now our application is ready you can test by executing below command.

$ ./gradlew run

http://localhost:8080/randomplay

JSON output 

{

 name: “Tee Phularani”

}

Let us create a Graal native image.

Micronaut only supported in Java or Kotlin for graal native-image.

While creating a project we have added — features=graal-native-image this is adding three important features. 

  1. svm(Substrate VM) and graal dependencies in build.gradle.
compileOnly "org.graalvm.nativeimage:svm"
annotationProcessor "io.micronaut:micronaut-graal"

2. A Dockerfile which can be used to construct the native image executing docker-build.sh

3. A native-image.properties file in the resource directory.

Args = -H:IncludeResources=logback.xml|application.yml|bootstrap.yml \
       -H:Name=helloworld-graal \
       -H:Class=helloworld.graal.Application

This is very easy for developer to create a native image inside docker. Fire below two commands: 

$ ./gradlew assemble
$ ./docker-build.sh

Once image is ready we can create a container to verify our understanding. 

$ docker run -p 8080:8080 helloworld-graal

To test the application you can use curl with time:

$ time curl localhost:8080/randomplay

This is for now. You can check the time difference with native image executable and docker with a native image. 

Source code download or clone from github: https://github.com/maheshwarLigade/micronaut-examples/tree/master/helloworld-graal

Dockerise Micronaut application.

Micronauts is a java framework to develop a cloud-native microservices application easily and seamlessly. If you don’t know about Micronaut Please go through below two articles. 

Installation of Micronaut on Mac(OSX) & Linux.
Micronaut java full stack Microservice Framework!!

In this article, we are exploring a micronaut framework and How to dockerize it. 

Let us create a small micronaut REST service application and try to dockerize it.

Micronaut provides a CLI option to create an application easily.

$ mn create-app helloworld

This will scaffold a new Gradle project. If you prefer Maven, add a --build maven parameter. If you want to create a new Groovy or Kotlin project, add a --lang parameter.

$ mn create-app --lang groovy helloworld-groovy
$ mn create-app --lang kotlin helloworld-kotlin

These options depend on you, which language are you comfortable with.

These options depend on you, which language are you comfortable with. 

Once the project is ready we can import that in your favorite editor. I am using IntelliJ.

We are using already created Hello world app, source code is available at below location you can clone

https://github.com/maheshwarLigade/micronaut-examples/tree/master/helloworld

By default, micronaut app can create Docker file for you and docker file you can locate on current directory of your project <appname>/Docker 

e.g helloworld/Docker

The Default content of Docker file:

FROM adoptopenjdk/openjdk13-openj9:jdk-13.0.2_8_openj9-0.18.0-alpine-slim
COPY build/libs/helloworld-*-all.jar helloworld.jar
EXPOSE 8080
CMD ["java", "-Dcom.sun.management.jmxremote", "-Xmx128m", "-XX:+IdleTuningGcOnIdle", "-Xtune:virtualized", "-jar", "helloworld.jar"]

If you are familiar with docker then fine if not you can explore below article to understand docker.

https://www.techwasti.com/demystify-docker-container-technology-9a8e1ec3968b/

Micronaut create docker file with alpine-slim 

and JDK image which is used here is unofficial.

This repo provides Unofficial AdoptOpenJDK Docker Images,

Reference:- https://hub.docker.com/r/adoptopenjdk/openjdk13-openj9

Thrid line to copy the generated jar(helloworld.jar) file and the expose default port as 8080. Last line to launch the jar file.

For this example, I am using Gradle as a build tool

$ cd helloworld
$ ./gradlew run

To test whether code is working fine or not. (curl http://localhost:8080/hello)

Now build a Docker image from the docker file for that fire below command. 

To run the application with IntelliJ IDEA, you need to enable annotation processing:

  1. open Settings → Build → Execution → Deployment → Compiler →Annotation Processors
  2. Set the checkbox Enable annotation processing

As we know micronaut CLI generates a Dockerfile by default, making it easy to package your application for a container environment such as Kubernetes.

$ docker build . -t hello-world-ex

Fire above command to create a docker image. -t 1.0.0 indicates the tag for this image. Now our image is ready to make a container from its fire below command. 

$ docker run --rm -p 8080:8080 hello-world-ex

As we have exposed 8080 port in docker file. We are doing port mapping to an external system.

to verify the docker image fire below command.

$ curl http://localhost:8080/hello

In this article, we have seen dockerizing micronaut apps. We have created helloworld application and created a docker image using the existing Docker file. You can edit the docker file and optimize it as per your requirement. 

Installation of Micronaut on Mac(OSX) & Linux.

Micronaut is a full framework to develop cloud native microservice architecture based application using java, kotlin or Groovy.

Let us check the steps required to install micronaut on OSx.

Simple and effortless start on Mac OSX, Linux, you can use SDKMAN! (The Software Development Kit Manager) to download and configure any Micronaut version of your choice.

INSTALLING WITH SDKMAN:

This tool makes installing of a Micronaut on any Unix based platform such as Linux, OSx.

Open a terminal and install SDKMAN,

$  curl -s https://get.sdkman.io | bash

Follow the on-screen instructions to complete installation.

Then fire below command after installation of SDKMAN to configure SDKMAN.

 $ source "$HOME/.sdkman/bin/sdkman-init.sh"

Once above two steps are in align then go and setup micrnaut using SDKMAN,

$ sdk install micronaut

After installation is complete it can be validated with below command.

$ mn --version
installation and validation of micronaut

this is the simple steps with SDKMAN.

INSTALLING WITH HomeBrew:

Before installation using homebrew you should update homebrew version

$ brew update

In order to install Micronaut, run following command:

$ brew install micronaut

After installation is complete it can be validated with below command.

$ mn --version

Installing with MacPorts:

Before installing it is recommended to sync the latest Portfiles, So that there shouldn’t be any issue,

$ sudo port sync

To install Micronaut, run following command

$ sudo port install micronaut

After installation is complete it can be validated with below command.

$ mn --version

Above are they three different way we can setup micronaut framework on MacOS and linux based OS.

Configuration as a Service: Spring Cloud Config – using kotlin.

Developing a microservice architecture with Java and Spring Boot is quite popular these days. In microservice architecture we hundreds of services and managing services for each service and for each profile which is a quite tedious task. In this article, we will demonstrate the Spring cloud config server using kotlin. 

Spring Boot provided a much-needed spark to the Spring projects.

Spring cloud-config provides a server and client-side support for externalizedconfiguration in a distributed system. With the Config Server, you have a central place to manage external properties for applications across all environments.

From the above diagram, you can easily predict that in distributed systems managing configuration as a central service is a bit tedious task and spring cloud config provide client, server architecture mechanism to manage the configuration easily. 

Let us go to the https://start.spring.io/

When we do any changes in any service we have to restart the services to apply the changes.

Let us create one git repo to manage our configuration and to achieve this we are creating one git repo.

So we will create “springbootclient” as one small spring boot microservice to take the username and that will read username from spring cloud config central configuration server system i.e git here.

We have created three different properties files for each of our different environments. 

  1. springbootclient.properties
  2. springbootclient-dev.properties
  3. springbootclient-prod.properties

https://github.com/maheshwarLigade/cloud-common-config-server

Here is our spring cloud config properties are available, you can clone or use directly this repository too.

Now as we have created spring config server application using spring starter let us download and import that project in your favorite IDE or editor. git repo here we used to store our configuration and spring cloud config server application is to serve those properties to the client.

Basically git is datastore, spring cloud config server is server application and there are multiple microservices are the clients which needs configurations.

Now our git as datastore is ready. In this repository, we have created one sample client application and the name of that app is springbootclient. In the future microservice article we will utilize the same spring cloud config as a configuration server.

Let us go and check the code base for the client app.

This is the sample application.properties file:

server.port=8888
logging.level.org.springframework.cloud.config=DEBUG
spring.cloud.config.server.git.uri=https://github.com/maheshwarLigade/cloud-common-config-server.git
spring.cloud.config.server.git.clone-on-start=true
spring.cloud.config.server.git.searchPaths=springbootclient

Sample Code for SpringCloudConfigServerexApplication.kt

import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.runApplication
import org.springframework.cloud.config.server.EnableConfigServer

@SpringBootApplication
@EnableConfigServer
class SpringCloudConfigServerexApplication

fun main(args: Array<String>) {
   runApplication<SpringCloudConfigServerexApplication>(*args)
}

Now run and up the spring cloud-config server and check the below URL:

http://localhost:8888/springbootclient/dev/master

Spring Boot Client App:

Let us create one small microservice which will read configuration from spring cloud config server and serve that property value over REST end point.

Go to the https://start.spring.io/ and create spring boot client microservice using kotlin.

Sample POM.xml dependencies.

<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
   <groupId>com.fasterxml.jackson.module</groupId>
   <artifactId>jackson-module-kotlin</artifactId>
</dependency>
<dependency>
   <groupId>org.jetbrains.kotlin</groupId>
   <artifactId>kotlin-reflect</artifactId>
</dependency>
<dependency>
   <groupId>org.jetbrains.kotlin</groupId>
   <artifactId>kotlin-stdlib-jdk8</artifactId>
</dependency>
<dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-starter-config</artifactId>
</dependency>

Now check the SpringCloudClientAppApplication.kt code

import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.runApplication

@SpringBootApplication
class SpringCloudClientAppApplication

fun main(args: Array<String>) {
    runApplication<SpringCloudClientAppApplication>(*args)
}

Now create one sample REST controller which is serving REST request. We want to check ” /whoami” this endpoint is returning which is the user based on active profile dev, prod, etc.

UserController.kt

import org.springframework.beans.factory.annotation.Value
import org.springframework.web.bind.annotation.GetMapping
import org.springframework.web.bind.annotation.RestController


@RestController
class UserController {

    @Value("\${app.adminusername}")
    var username="Test"
//get request serving
    @GetMapping("/whoami")
    fun whoami() = "I am a  "+ username

}

Create a bootstrap.properties file where we will specify the spring cloud config server details, which is a git branch and what is active profile dev, local, prod, etc.

spring.application.name=springbootclient
spring.profiles.active=dev
spring.cloud.config.uri=http://localhost:8888
spring.cloud.config.fail-fast=true
spring.cloud.config.label=master

All properties are self exclamatory, what is the use of which one.

Once you hit this URL http://localhost:9080/whoami

Output:- I am a DevUser

Github source link:

Config Server: https://github.com/maheshwarLigade/cloud-common-config-server

Codebase: https://github.com/maheshwarLigade/spring-cloud-config-kotlin-ex

More such Stories

Enable Spring security using kotlin!!

Spring security is the defacto abstraction in the spring framework world to add authentication and authorization layer for your application. There are plenty of examples. In this article, we have spring security using kotlin.

In the last article, we have seen that and developed Spring Boot, MongoDB REST API using kotlin. We will use the same example to add spring security dependency.

https://github.com/maheshwarLigade/springboot-mongodb.restapi/tree/master

To illustrate spring-security example add spring security starter dependency.

implementation("org.springframework.boot:spring-boot-starter-security")

If you are in favor of the Maven build tool then use below dependency.

<dependency> 
<groupId>org.springframework.boot</groupId> 
<artifactId>spring-boot-starter-security</artifactId> 
</dependency>

As our existing example of REST API using kotlin. it contains patient data and CRUD operation so we will have two different roles, ADMIN and Doctor. 

For simplification, we will have two roles only and we will only one endpoint “\patients” with five different operations. We will secure all our end point either using @Secured annotation or config class.

import org.springframework.context.annotation.Bean
import org.springframework.context.annotation.Configuration
import org.springframework.http.HttpMethod
import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder
import org.springframework.security.config.annotation.web.builders.HttpSecurity
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder
import org.springframework.security.crypto.password.PasswordEncoder

@Configuration
class SecurityConfig : WebSecurityConfigurerAdapter() {

    @Bean
    fun encoder(): PasswordEncoder {
        return BCryptPasswordEncoder()
    }

    override fun configure(auth: AuthenticationManagerBuilder) {
        auth.inMemoryAuthentication()
                .withUser("admin")
                .password(encoder().encode("pass"))
                .roles("DOCTOR", "ADMIN")
                .and()
                .withUser("doctor")
                .password(encoder().encode("pass"))
                .roles("DOCTOR")
    }

    @Throws(Exception::class)
    override fun configure(http: HttpSecurity) {
        http.httpBasic()
                .and()
                .authorizeRequests()
                .antMatchers(HttpMethod.GET, "/patients").hasRole("ADMIN")
                .antMatchers(HttpMethod.POST, "/patients/**").hasRole("ADMIN")
                .antMatchers(HttpMethod.PUT, "/patients/**").hasRole("ADMIN")
                .antMatchers(HttpMethod.DELETE, "/patients/**").hasRole("ADMIN")
                .antMatchers(HttpMethod.GET, "/patients/**").hasAnyRole("ADMIN", "DOCTOR")
                .and()
                .csrf().disable()
                .formLogin().disable()
    }

}

As we have five operations and two roles ADMIN and DOCTOR.

If you don’t want to encrypt the password you can use a plain text password with {noop} prefix.

First step where we have declared two users and then which endpoints do we want to secure and https method those we have configured. 

In this example we have two get endpoints first one to get all records of patients and another one is a specific patient record. This is a very good use case because 

  1. Get ALL patient only admin can access
  2. Get a particular patient that endpoint is accessible DOCTOR who treats him/her and ADMIN as well who has access to everything. 

csrf().disable is about disabling Spring Security built-in cross-site scripting protection.

formLogin().disable() is about disabling default login form.

Now everything is ready we have secured our REST endpoint. Let us hit all the REST endpoints in a previous way, you will get 401/403 HTTP status code. Try using the CURL command. 

$ curl localhost:8090/patients 
{   
"timestamp": "2020-04-12T05:37:16.718+0000",
"status": 401,   
"error": "Unauthorized",   
"message": "Unauthorized",   
"path": "/patients"
}

$ curl localhost:8090/patients -u admin:pass

Use the above endpoint and you will get successful results.

This is it for now about this. I know this is a very simple use case and example too but you can use the same structure and scale that to next level using a database with different user roles and access control lists.

GitHubCode Repo:-

https://github.com/maheshwarLigade/springboot-mongodb.restapi/tree/master

Spring Boot, MongoDB REST API using Kotlin.

As part of this article our focus to develop simple REST API using spring boot and MongoDB. 

Getting started with this is the Spring Initialiser tool: https://start.spring.io/

In this example, I am considering gradle as build tool and MongoDB as Database.

Download and import Project into your favorite editor, I prefer intellij,

Either you can install MongoDB on your local or you can use MongoDB hosted solution https://mlab.com/.

I am using mlab.com for this example.

Let us provide the MongoDB connection details in the application.properties

spring.data.mongodb.host=localhost #for now I kept localhost
spring.data.mongodb.port=27017
spring.data.mongodb.database=mongo-rest-api-kotlin-demo

Let us create entity class as Patient.

@Document
data class Patient (
        @Id
        val id: ObjectId = ObjectId.get(),
        val name: String,
        val description: String,
        val createdDate: LocalDateTime = LocalDateTime.now(),
        val modifiedDate: LocalDateTime = LocalDateTime.now()
)

@Document annotation rather than @Entity is used here for marking a class which objects we’d like to persist to the mongodb. 

@Id: is used for marking a field used for identification purposes. 

Also, we have provided some default values for the created date and modified date.

Let us create a repository interface.

import org.bson.types.ObjectId
import org.springframework.data.mongodb.repository.MongoRepository

interface PatientRepository : MongoRepository<Patient, String> {
    fun findOneById(id: ObjectId): Patient
    override fun deleteAll()

}

The repository interface is ready to use, we don’t have to write an implementation for it. This feature is provided by SpringData JPA. Also, MongoRepository interface provides all basic methods for CRUD operations. For now, we will consider only finOneById.

Now our backend is ready, let us write down the REST Controller which will serve our request efficiently.

@RestController
@RequestMapping("/patients")
class PatientController(
        private val patientsRepository: PatientRepository
) {

    @GetMapping
    fun getAllPatients(): ResponseEntity<List<Patient>> {
        val patients = patientsRepository.findAll()
        return ResponseEntity.ok(patients)
    }

    @GetMapping("/{id}")
    fun getOnePatient(@PathVariable("id") id: String): ResponseEntity<Patient> {
        val patient = patientsRepository.findOneById(ObjectId(id))
        return ResponseEntity.ok(patient)
    }
}

Now our basic Controller is ready, let us write some test cases.

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
@ExtendWith(SpringExtension::class)
@TestInstance(TestInstance.Lifecycle.PER_CLASS)
class PatientControllerIntTest @Autowired constructor(
        private val patientRepository: PatientRepository,
        private val restTemplate: TestRestTemplate
) {
    private val defaultPatientId = ObjectId.get()

    @LocalServerPort
    protected var port: Int = 0

    @BeforeEach
    fun setUp() {
        patientRepository.deleteAll()
    }


    private fun getRootUrl(): String? = "http://localhost:$port/patients"

    private fun saveOnePatient() = patientRepository.save(Patient(defaultPatientId, "Name", "Description"))

    @Test
    fun `should return all patients`() {
        saveOnePatient()

        val response = restTemplate.getForEntity(
                getRootUrl(),
                List::class.java
        )

        assertEquals(200, response.statusCode.value())
        assertNotNull(response.body)
        assertEquals(1, response.body?.size)
    }

    @Test
    fun `should return single patient by id`() {
        saveOnePatient()

        val response = restTemplate.getForEntity(
                getRootUrl() + "/$defaultPatientId",
                Patient::class.java
        )

        assertEquals(200, response.statusCode.value())
        assertNotNull(response.body)
        assertEquals(defaultPatientId, response.body?.id)
    }
}

Here we are using spring boot test to do integration testing also SpringBootTest.WebEnvironment.RANDOM_PORT is used here.

Note:

https://kotlinlang.org/docs/reference/coding-conventions.html#naming-rules

Please consider the naming convention while writing test cases for kotlin.

In JVM world similar conventions are well-known in Groovy and Scalaworld.

Always start with simple steps first, we will write down get operation first, try to fetch all Patient details.

Run the application and hit the http://localhost:8090/patients endpoint.

Let us create a POST request.

Create one simple request Object that will help us to create entity in mango world.

class PatientRequest(
        val name: String,
        val description: String
)

Here we will Pass patient names and descriptions about treatment. 

Now go to the REST Controller and handle a POST request.

@PostMapping
fun createPatient(@RequestBody request: PatientRequest): ResponseEntity<Patient> {
    val patient = patientsRepository.save(Patient(
            name = request.name,
            description = request.description
    ))
    return ResponseEntity(patient, HttpStatus.CREATED)
}

Let us create a method to create a PUT method to handle amendments in a document.

@PutMapping("/{id}")
fun updatePatient(@RequestBody request: PatientRequest, @PathVariable("id") id: String): ResponseEntity<Patient> {
    val patient = patientsRepository.findOneById(ObjectId(id))
    val updatedPatient = patientsRepository.save(Patient(
            id = patient.id,
            name = request.name,
            description = request.description,
            createdDate = patient.createdDate,
            modifiedDate = LocalDateTime.now()
    ))
    return ResponseEntity.ok(updatedPatient)
}

Test Method for an Update operation.

@Test
fun `should update existing patient`() {
    saveOnePatient()
    val patientRequest = preparePatientRequest()

    val updateResponse = restTemplate.exchange(
            getRootUrl() + "/$defaultPatientId",
            HttpMethod.PUT,
            HttpEntity(patientRequest, HttpHeaders()),
            Patient::class.java
    )
    val patientRequest = patientRepository.findOneById(defaultPatientId)

    assertEquals(200, updateResponse.statusCode.value())
    assertEquals(defaultPatientId, patientRequest.id)
    assertEquals(patientRequest.description, patientRequest.description)
    assertEquals(patientRequest.name, patientRequest.name)
}

Now our update operation is ready.

Let us Delete records using Delete operation.

As the deleted document won’t be included in the response, the 204 code will be returned.

@DeleteMapping("/{id}")
fun deletePatient(@PathVariable("id") id: String): ResponseEntity<Unit> {
    patientsRepository.deleteById(id)
    return ResponseEntity.noContent().build()
}

Test method which is straight forward to test delete method.

@Test
fun `should delete existing patient`() {
    saveOnePatient()

    val delete = restTemplate.exchange(
            getRootUrl() + "/$defaultPatientId",
            HttpMethod.DELETE,
            HttpEntity(null, HttpHeaders()),
            ResponseEntity::class.java
    )

    assertEquals(204, delete.statusCode.value())
    assertThrows(EmptyResultDataAccessException::class.java) { patientRepository.findOneById(defaultPatientId) }
}

Now our all CRUD operations are ready, run the application

This is for now Code is available on Github

https://github.com/maheshwarLigade/springboot-mongodb.restapi/tree/master

Monitor spring boot app using Spring Boot Admin.

Administration of spring boot applications using spring boot admin.

This includes health status, various metrics, log level management, JMX-Beans interaction, thread dumps and traces, and much more. Spring Boot Admin is a community project initiated and maintained by code-centric.

Spring boot admin will provide UI to monitor and do some administrative work for your spring boot applications.

This project has been started by codecentric and its open source. You can do your own customization if you want to.

Git Repo:

https://github.com/codecentric/spring-boot-admin

The above video will give you a better idea of what is this project, so we will directly start with an example.

Spring Boot provides actuator endpoints to monitor metrics of individual microservices. These endpoints are very helpful for getting information about applications like if they are up if their components like database etc are working well. But a major drawback or difficulty about using actuator endpoints is that we have to individually hit the endpoints for applications to know their status or health. Imagine microservices involving 150 applications, the admin will have to hit the actuator endpoints of all 150 applications. To help us to deal with this situation we are using Spring Boot Admin app.

Sample Code:

To implement this we will create two projects one is server and another is the client.

  1. Spring Boot Admin server.
  2. Spring Boot Admin client.

Spring Boot Admin Server:

The project structure should look like any spring boot application:

POM.xml 

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>com.techwasti</groupId>
	<artifactId>spring-boot-admin</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>spring-boot-admin</name>
	<description>Demo project for Spring Boot</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.5.4.RELEASE</version>
		<relativePath /> <!-- lookup parent from repository -->
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>
<!-- admin dependency-->
		<dependency>
			<groupId>de.codecentric</groupId>
			<artifactId>spring-boot-admin-server-ui-login</artifactId>
			<version>1.5.1</version>
		</dependency>
		<dependency>
			<groupId>de.codecentric</groupId>
			<artifactId>spring-boot-admin-server</artifactId>
			<version>1.5.1</version>
		</dependency>
		<dependency>
			<groupId>de.codecentric</groupId>
			<artifactId>spring-boot-admin-server-ui</artifactId>
			<version>1.5.1</version>
		</dependency>
<!-- end admin dependency-->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-security</artifactId>
		</dependency>

	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>


</project>

We need to configure security as well since we are accessing sensitive information:

package com.techwasti;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;

import de.codecentric.boot.admin.config.EnableAdminServer;

@EnableAdminServer
@Configuration
@SpringBootApplication
public class SpringBootAdminApplication {

	public static void main(String[] args) {
		SpringApplication.run(SpringBootAdminApplication.class, args);
	}

	@Configuration
	public static class SecurityConfig extends WebSecurityConfigurerAdapter {
		@Override
		protected void configure(HttpSecurity http) throws Exception {
			http.formLogin().loginPage("/login.html").loginProcessingUrl("/login").permitAll();
			http.logout().logoutUrl("/logout");
			http.csrf().disable();

			http.authorizeRequests().antMatchers("/login.html", "/**/*.css", "/img/**", "/third-party/**").permitAll();
			http.authorizeRequests().antMatchers("/**").authenticated();

			http.httpBasic();
		}
	}

}

application.propertie file content

spring.application.name=SpringBootAdminEx
server.port=8081
security.user.name=admin
security.user.password=admin

Run the app and localhost:8081


Enter username and password and click on button login.

As this is a sample example so we hardcoded username and password but you can use spring security to integrate LDAP or any other security.

Spring Boot Admin can be configured to display only the information that we consider useful.

spring.boot.admin.routes.endpoints=env, metrics, trace, info, configprops

Notifications and Alerts:

We can notify and send alerts using any below channels.

  • Email
  • PagerDuty
  • OpsGenie
  • Hipchat
  • Slack
  • Let’s Chat

Spring Boot Admin Client:

Now we are ready with the admin server application let us create the client application. Create any HelloWorld spring boot application or if you have any existing spring boot app you can use the same as a client application.

Add below Maven dependency 

<dependency>
			<groupId>de.codecentric</groupId>
			<artifactId>spring-boot-admin-starter-client</artifactId>
			<version>1.5.1</version>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-actuator</artifactId>
		</dependency>

Next, update application.properties and add the following properties

spring.boot.admin.url=http://localhost:8081
spring.boot.admin.username=admin
spring.boot.admin.password=admin

These changes are fine in your client application now run the client application. Once the client application is up and running go and check your admin server application. It will show all your applications.

Beautiful Dashboards:

References:-

codecentric/spring-boot-admin
This community project provides an admin interface for Spring Boot ® applications. It provides the following features…github.comSpring Boot

Admin Reference Guide
@Configuration @EnableAutoConfiguration @EnableDiscoveryClient @EnableAdminServer public class…codecentric.github.io

Best resources to learn Go programming language!!

Golang aka go programming language is the fastest-growing programming most loved programming language.

If you think you are not used ” go ” directly or indirectly then I think you are wrong. Have you heard about Docker containerization technology then you are indirectly using Go language in your day to day basis.

Docker is written in the Google Go programming language.

What is GoLang?

Go-Lang is an open-source language officially released by the Google production team in 2009. It was developed by Robert Griesemer, Ken Thompson and Rob Pike. It is a multi-purpose programming language specially designed to build faster and scalable applications. It provides features like fast compilation, garbage collection, dynamic types, concurrency, standard libraries, and packages.

Let us take a tour to understand what are the best resources available to get started this programming language.

1. Go Tour:-  

This is my favorite site to get started and make our hands dirty. This is the official Go Tour website: https://tour.golang.org. The best things about this site are that the tour is available offline just by running go tool tour in your command line if you have already installed Go-lang locally. This is providing an interactive tutorial where you can run your code snippet and it gives you an overview of Go-Lang. The tour is classified into different sets of modules.

2. Go By Example:- 

Another effective to start go-lang learning is going by example. Go by Example is an interactive online course tutorial for learning Go. Once you know the basic then go ahead and hit the Go by example (https://gobyexample.com). Start hacking by taking examples and get moderate knowledge about go-lang. 

3. Effective Go:-

This is another official resource to learn go-lang. This is also available for free. This is a very interesting website https://golang.org/doc/effective_go.html to explore more about the go-lang. I found it very useful especially because is not just a syntax reference document but a more complete description of all the Go features and constructs and how to use them effectively. This is where you will get some level of expertise.

4.Golangbootcamp:-

Golang Bootcamp is a mini book to start learning go-lang. How to get started on Go? Hit this URL http://www.golangbootcamp.com/book/ to explore this book. This book will open a window for you to start learning effectively go-lang. The best thing about this mini-book is, it has a list of basic constructs and concepts and all those attached with go-lang playground. 

5. Go-Playground:- 

Now you know basic of go-lang language and you know how to construct the things. you no need to install go-lang locally on your system to start. We have online https://play.golang.org/ go-lang playground to test your knowledge and constructs. 

6. Go-Lang FAQ:-

Go-lang FAQ is really golden gate for you to understand the core concept and clarify your Bigbang doubts. This is also an official website https://golang.org/doc/faq.

7. Go-lang Bot:-

Golangbot is a fun and easy way to follow and learn Golang consistently and regularly. This can help you in improving your coding, solving practical issues, basics of Golang to advanced tutorials. This is inclusive of all learning materials of Golang. here you will get a different experience of learning. 

Hit this URL to go https://golangbot.com/ and start with hello world to a complex program and Quizs too.  

8. Tutorials Point:-

The tutorials point is also one of the best resources to get familiar with go-lang. if you are an avid reader and learner you should know tutorials point. 

https://www.tutorialspoint.com/go/.

9. Go-Lang Tutorials:-

GoLang tutorials is the best free online classes to learn go-lang. These classes best suited for professionals as well as beginners. It has a cover of the basic concept, control flow, looping, interfaces, memory management, etc. Tutorials are classifieds into sections and all sections having examples.Table of Contents
Audience Installing and configuring Go A step by step approach to Hello World in Go Updated for Go1 Typical early…golangtutorials.blogspot.com

10. Reference Books:-

  1. Introducing Go by O’Reilly.
  2. Go in Action.
  3. Learning Functional Programming in Go.

Conclusion:-

These are my findings. Please let us know your resources to learn go-lang. How you started and what are the other resources do you think are better to start learning go-lang.

CI and CD with GitHubActions!!

GitHub Actions make it easy to automate all your software workflows, now with world-class CI/CD.

github.com

Github actions are a tool to run workflow on any GitHub event.

In today’s era DevOps and Continous integration and continuous deployment. Every organization wants to become agile and develope features, build and deploy a daily or hourly basis. To do this every enterprise uses their own set of tools to watch over source version control such as git then generate a build and execute unit test cases, then functional, integration test cases after that based on threshold do some monkey testing in a simulated environment and then deploy to lower environment and then do promotion. 

The above one is the general flow in any enterprise software. Nowadays everyone wants to fail fast, this leads to come up with different tools such as Jenkins, chef, git, sonarqube and many more. Based on the coding language and deployment server you have to choose the tools. If you are using Docker or containers then different tools.

To make things simple yet powerful and efficient github come up with Github Actions. GitHub Actions features a powerful execution environment integrated into every step of your workflow. You can discover, create, and share actions to perform any job you’d like, and combine them to customize your workflow.

Build, test, and deploy your code right from GitHub. Make code reviews, branch management, and issue triaging work the way you want.

The best thing about this is you can do this in your github repository itself.

There are different sets of actions such as assign reviewers, revert commit, merge, package, publish, etc. for more details visit below pageGitHub Marketplace: actions to improve your workflow
Menu Types Categories Filters Verification An entirely new way to automate your development workflow. 1712 results…github.com

Some important points:-

  1. GitHub Actions support Node.js, Python, Java, Ruby, PHP, Go, Rust, .NET, and more.
  2. Save time with matrix workflows that simultaneously test across multiple operating systems and versions of your runtime.
  3. Run directly on a VM or inside a container. Use your own VMs, in the cloud or on-prem, with self-hosted runners. Hosted runners for every major OS.
  4. It’s one click to copy a link that highlights a specific line number to share a CI/CD failure. You will get live logs.
  5. Built-in secret store.
  6. Multi-container testing.
  7. Community-powered workflows.
  8. Write and Reuse the workflows.
  9. Built-in github package registry.
  10. Simple, pay-as-you-go pricing.

Pricing:- 

Free for open-source projects.

https://github.com/features/actions

Actions allow us to easily test multiple versions of your project in parallel.

Getting started:-

Let us create one sample repository on your github. Go to that repository and on the top section below your repository name, you will see “Actions” as a menu click on it.

When you click on it you can see the Actions page, where you will see list of predefined templates for it.

Choose the one which is suitable for your requirements. Click on “set up this workflow” click on this button.

It will redirect you to the actual workflow page, where we have to define workflow using “yml” 

Define workflow if require add some workflow tool from the marketplace and commit the code. If you want to preview your flow click on “Preview” button which is next to the edit file. Once you commit it will in the “Actions” menu we can see workflow like below. Here we can see status here also we can define a new workflow. The different workflow may be based on the environment like dev, QA, UAT or PROD.

Check the status and enjoy coding.

Sample yml:-

jobs:
  test:
    name: Test on node ${{ matrix.node_version }} and ${{ matrix.os }}
    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
        node_version: [8, 10, 12]
        os: [ubuntu-latest, windows-latest, macos-latest]

    steps:
    - uses: actions/[email protected]

    - name: Use Node.js ${{ matrix.node_version }}
      uses: actions/[email protected]
      with:
        version: ${{ matrix.node_version }}
    
    - name: npm install, build and test
      run: |
        npm install
        npm run build --if-present
        npm test

Documentation:-

Automating your workflow with GitHub Actions
GitHub Actions features a powerful execution environment integrated into every step of your workflow. You can discover…help.github.com

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