Spring on Micha Kops' Tech Notes

Forwardings Requests to static content in Spring Boot Webflux

Tue, 16 Aug 2022 00:00:00 +0200

The following WebFilter redirects incoming requests for / to a static HTML file, index.html.

ToIndexPageRedirection.java

package com.hascode.tutorial;

import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.server.WebFilter;
import org.springframework.web.server.WebFilterChain;
import reactor.core.publisher.Mono;

@Component
public class ToIndexPageRedirection implements WebFilter {
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
        if (exchange.getRequest().getURI().getPath().equals("/")) {
            return chain.filter(
                exchange.mutate().request(
                    exchange.getRequest().mutate().path("/index.html").build()
                ).build()
            );
        }

        return chain.filter(exchange);
    }
}

Ressources:

JavaDocs WebFilter

Spring Boot Kafka Increase Message Size Limit

Thu, 09 Jun 2022 00:00:00 +0200

Let’s say we would like to increase the limit t 10MB …

Broker Configuration

Apply the new limit either by modifying the server.properties like this…

max.message.bytes=10485760

or apply it to a specific topic using

kafka-configs.sh --bootstrap-server localhost:9092 \
    --entity-type topics  \
    --entity-name thetopic \
    --alter \
    --add-config max.message.bytes=10485760

Producer Configuration for Spring Boot

We simply need to add the following line to our application.properties:

spring.kafka.producer.properties.max.request.size=spring.kafka.producer.properties.max.request.size

The following proof-of-concept demonstrates that without the property, sending a large message fails, with the property it succeeds:

Embedded Kafka for Spring Boot Testing without using Docker

Wed, 25 May 2022 00:00:00 +0200

Sometimes it is nice to set up an embedded Kafka broker for testing without the need to have Docker installed (e.g. for using testcontainers-lib).

The following snippet shows, how to set up an embedded Kafka instance for testing for a Spring Boot project.

Setup

Using Maven, this is our Spring Boot project with dependencies needed:

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>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>(1)
        <version>2.6.4</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <groupId>com.hascode.tutorial</groupId>
    <artifactId>kafka-testing</artifactId>
    <version>1.0.0-SNAPSHOT</version>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>17</java.version>
        <maven.compiler.source>${java.version}</maven.compiler.source>
        <maven.compiler.target>${java.version}</maven.compiler.target>
        <kafka.version>3.1.0</kafka.version>(2)
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.kafka</groupId>
            <artifactId>spring-kafka</artifactId>(3)
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.kafka</groupId>
            <artifactId>spring-kafka-test</artifactId>(4)
            <scope>test</scope>
        </dependency>

        <dependency>(5)
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-api</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-engine</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.junit.platform</groupId>
            <artifactId>junit-platform-launcher</artifactId>
            <scope>test</scope>
        </dependency>
        [..]
</project>

Configuring Spring Boot WebserviceTemplate to sign WSS SOAP Requests

Wed, 30 Mar 2022 00:00:00 +0200

Sometimes when accessing SOAP APIs, our SOAP client needs to sign the request. How this can be achieved using Spring Boot’s WebserviceTemplate within a few steps is the scope of this short article.

This snippet only deals with the client side not with the security configuration on the server side.

Also it assumes, that you have already set up your keystore/truststore and that you’re loading these with your Spring Boot application’s startup without errors.

Logback and Spring Boot - Change Log Level to custom format

Thu, 19 Aug 2021 00:00:00 +0200

Create a custom converter

This class converts the well known log levels to a custom format

CustomLogLevelConverter.java

package com.hascode;

public class CustomLogLevelConverter extends ClassicConverter {
    @Override
    public String convert(ILoggingEvent event) {
        switch (event.getLevel().toInt()) {
            case Level.ERROR_INT:
                return "ERROR!!!";
            case Level.WARN_INT:
                return "WARN!!";
            case Level.INFO_INT:
                return "INFO!";
            case Level.TRACE_INT:
                return "DEBUG";
            default:
                return event.getLevel().toString();
        }
    }
}

Register the converter

The following Logback config includes some defaults and registers our custom converter.

Package a Spring Boot App as RPM

Fri, 14 May 2021 00:00:00 +0200

Goals

Package a Spring Boot Service as RPM Package
Configure systemd integration
Add install/uninstall hooks to create users, directories etc.

Maven Setup

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.4.2</version>
    <relativePath/>
  </parent>
  <groupId>com.hascode</groupId>
  <artifactId>sample-app</artifactId>
  <version>1.0.0-SNAPSHOT</version>
  <name>sample-app</name>

  <properties>
    <java.version>11</java.version>
  </properties>
  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin> (1)
        <groupId>de.dentrassi.maven</groupId>
        <artifactId>rpm</artifactId>
        <version>1.5.0</version>
        <executions>
          <execution>
            <goals>
              <goal>rpm</goal>
            </goals>
          </execution>
        </executions>
        <configuration>
          <packageName>sample-app</packageName>
          <skipSigning>true</skipSigning>
          <group>Application/Misc</group>
          <requires>
            <require>java-11-openjdk-headless</require> (2)
          </requires>
          <entries>
            <entry> (3)
              <name>/opt/sample-app</name>
              <directory>true</directory>
              <user>root</user>
              <group>root</group>
              <mode>0755</mode>
            </entry>
            <entry> (4)
              <name>/opt/sample-app/log</name>
              <directory>true</directory>
              <user>sample-app</user>
              <group>sample-app</group>
              <mode>0750</mode>
            </entry>
            <entry> (5)
              <name>/opt/sample-app/sample-app.jar</name>
              <file>${project.build.directory}/${project.build.finalName}.jar</file>
              <user>root</user>
              <group>root</group>
              <mode>0644</mode>
            </entry>
            <entry> (6)
              <name>/usr/lib/systemd/system/sample-app.service</name>
              <file>${project.basedir}/src/main/dist/sample-app.service</file>
              <mode>0644</mode>
            </entry>
          </entries>
          <beforeInstallation> (7)
            <file>${project.basedir}/src/main/dist/preinstall.sh</file>
          </beforeInstallation>
          <afterInstallation>
            <file>${project.basedir}/src/main/dist/postinstall.sh</file>
          </afterInstallation>
          <beforeRemoval>
            <file>${project.basedir}/src/main/dist/preuninstall.sh</file>
          </beforeRemoval>
          <license>All rights reserved</license>
        </configuration>
      </plugin>
    </plugins>
  </build>

</project>

Identity Management, One-Time-Passwords and Two-Factor-Auth with Spring Boot and Keycloak

Sun, 26 Nov 2017 00:00:00 +0100

Communicating with identity and access management systems is a common task for many web-applications exposing secured resources.

Keycloak is an open source software that provides not also such authorization services but also offers a lot of features from Single-Sign-On, Identity-Brokering, Social-Login, User-Federation, multiple client-adapters up to the administration console or support for protocols like OpenID, SAML, OAuth2, Kerberos and more.

I will demonstrate how to integrate a Spring Boot web application with Keycloak and configure an authentication flow that requires a two-factor-authentication with user credentials and also one-time-passwords.

Setting up an OAuth2 Authorization Server and Resource Provider with Spring Boot

Sun, 13 Mar 2016 00:00:00 +0100

OAuth2 is a frequently used standard for authorization and with Spring Boot it is easy to set up authorization and resource server in no time.

In the following short tutorial I’d like to demonstrate how to set up an OAuth2 authorization server as well as a connected and secured resource server within a few minutes using Java, Maven and Spring Boot.

Figure 1. OAuth2 Flow with Spring Boot in Action

Integrating Swagger into a Spring Boot RESTful Webservice with Springfox

Wed, 01 Jul 2015 00:00:00 +0200

Spring Boot allows us to create RESTful web-services with ease, Swagger specifies a format to describe the capabilities and operations of these services and with Swagger UI it is possible to explore our REST API with a nice graphical user interface in our browser.

Springfox is a project that aims at creating automated JSON API documentation for API’s built with Spring and is used in the following tutorial to integrate Swagger into a sample application.

Spring 3, Maven and Annotation Based Configuration

Sun, 22 Aug 2010 00:00:00 +0200

There is still the urban myth that using Spring IoC container without thousands lines of XML code isn’t possible – so today we’re taking a look at annotation based configuration with Spring 3 and of course we’re using Maven..

Setup your project

Create a simple Maven project using

mvn archetype:generate // or
mvn archetype:create

Add a lot of dependencies and reference them to the Spring version defined as a property in your pom.xml. A good reference on Spring 3 and Maven artifacts can be found at Springsource.com

<properties>
     <org.springframework.version>3.0.0.RELEASE</org.springframework.version>
 </properties>
 <dependencies>
     <dependency>
         <groupId>org.springframework</groupId>
         <artifactId>spring-core</artifactId>
         <version>${org.springframework.version}</version>
     </dependency>
     <dependency>
         <groupId>org.springframework</groupId>
         <artifactId>spring-expression</artifactId>
         <version>${org.springframework.version}</version>
     </dependency>

     <dependency>
         <groupId>org.springframework</groupId>
         <artifactId>spring-beans</artifactId>
         <version>${org.springframework.version}</version>
     </dependency>
     <dependency>
         <groupId>org.springframework</groupId>
         <artifactId>spring-aop</artifactId>
         <version>${org.springframework.version}</version>
     </dependency>
     <dependency>
         <groupId>org.springframework</groupId>
         <artifactId>spring-context</artifactId>
         <version>${org.springframework.version}</version>
     </dependency>
     <dependency>
         <groupId>org.springframework</groupId>
         <artifactId>spring-context-support</artifactId>
         <version>${org.springframework.version}</version>
     </dependency>
     <dependency>
         <groupId>org.aspectj</groupId>
         <artifactId>com.springsource.org.aspectj.runtime</artifactId>
         <version>1.6.8.RELEASE</version>
     </dependency>
 </dependencies>

Spring Boot Snippets

Mon, 01 Mar 2010 00:00:00 +0100

Define and Configure Log Groups

This allows to configure a group of loggers at the same time

Define a log group named myaspect with two packages
application.properties
```
logging.group.myaspect=com.hascode.package1,com.hascode.package2
```
Configure the log group and set all loggers to level TRACE
application.properties
```
logging.level.myaspect=TRACE
```

This is also possible as parameter on startup

java -Dlogging.level.myaspect=TRACE myapp.jar

Use JUnit 5 with Spring Boot

Use newer versions of Surefire and Failsafe plugins:

<properties>
[..]
  <maven-failsafe-plugin.version>2.22.0</maven-failsafe-plugin.version>
  <maven-surefire-plugin.version>2.22.0</maven-surefire-plugin.version>
</properties>