Don't Panic!

Test log4j with JUnit using a custom appender

January 15, 2018 – 8:21 pm

Following a recent article on how to Test System.out with JUnit, here’s a follow up on how to test log4J with JUnit. This article describes a technique to test log4J output in a JUnit test by adding a custom appender. This allows us to verify that log4j output contains expected Strings.

Tags appender, junit, log4j, Rule, voicexmlriot | Permalink | Comment (1)

How To

Validate JSPs at build time

November 13, 2017 – 7:44 pm

JSPs compile to Java code at run time. This is helpful if we want to test code changes without a build and deploy. However, if errors are introduced, they may not be spotted till it’s too late. A useful compromise is to validate JSPs at build time to verify that they will compile. The validator catches syntax errors before the application deploys and starts. This speeds up our build and test cycle and prevents silly mistakes slipping through to production code.

Tags jetty-jspc-maven-plugin, jsp, maven | Permalink | Comment (0)

How To Security Spring Boot

Thymeleaf and Spring Security

June 29, 2017 – 10:05 pm

Thymeleaf is a popular templating engine, particularly with Spring projects. Spring Boot has chosen Thymeleaf as the view technology of choice, largely replacing the need for JSP. With old JSPs, custom tag libraries provided integration with various technologies, including Spring Security. A similar library exists to integrate Thymeleaf and Spring Security – the Thymeleaf Spring read more »

Tags authentication, authorization, expression based annotations, integration module, jsp, method security expressions, PreAuthorize, role based access, server side security, spring boot, spring security, thymeleaf | Permalink | Comment (0)

How To Testing

Test System.out with JUnit

May 12, 2017 – 3:54 pm

It can be useful to verify output to System.out in a unit test. For example, if you’re testing application logging or if you’re using log output to sense some other behaviour. It can be tricky to properly mock behaviour of System.out but fortunately, it is possible to test System.out using JUnit.

Tags ExternalResource, junit, mock, PrintStream, Rule, system.out | Permalink | Comment (1)

How To Spring Boot

Spring Boot Actuator Trace: Logging HTTP requests

April 14, 2017 – 1:28 pm

Spring Boot Actuator provides assistance for application monitoring. Out of the box it provides information on application health, configuration and logging. It’s trivial to enable: simply add the spring-boot-starter-actuator dependency to a Spring Boot project in Maven or Gradle and it just works! The monitoring information is provided as JSON from HTTP endpoints or via JMX.

The Spring Boot Actuator trace endpoint is particularly handy. By default it shows the last 100 HTTP requests made to the application. This article walks through an Actuator demo and shows some of the configuration options to get the best from this feature.

Tags actuator, spring boot, trace | Permalink | Comments (3)

Docker How To

Tomcat debugging in Docker

March 12, 2017 – 7:42 pm

Like a many things in Tomcat, there are a number of ways to enable remote debugging. Here’s the easiest way I’ve found to enable remote debugging in a Docker container running Tomcat.

Tags debug, debugger, docker, eclipse, IDEA, intellij, jpda, tomcat | Permalink | Comment (0)

Docker How To

Activate the Docker Maven plugin when Docker is present

February 28, 2017 – 10:33 pm

The wonderful docker-maven-plugin from Spotify is a great way to build Docker images from Maven. If you bind it to Maven phases, it can be used to make a one-step build of a project artifact and its Docker image. For example, if you bind the Docker Maven plugin’s build goal to the Maven package phase, read more »

Tags docker, docker-maven-plugin, maven | Permalink | Comment (0)

How To Spring Boot

Spring Boot as a Windows Service

January 1, 2017 – 9:00 pm

The documentation provided by Spring on deploying a Spring Boot application as a Windows Service is a little sparse. Indeed, here it is in full:

Spring Boot application can be started as Windows service using winsw.

A sample maintained separately to the core of Spring Boot describes step-by-step how you can create a Windows service for your Spring Boot application.

— From Spring Boot Reference Guide (version 1.4.3), section 56.2: Microsoft Windows Services

As the official reference guide is lacking detail, here is a step by step guide to building and deploying a Spring Boot application as a Windows Service.

Tags jar, maven-assembly-plugin, package, service, spring boot, tanuki, tomcat, war, windows, winsw, wrapper | Permalink | Comments (4)

Spring Boot

Microservice discovery with Spring Boot and Eureka

September 12, 2016 – 11:43 pm

One of the standard problems with Microservices Architecture is the issue of service discovery. Once we’ve decomposed our application into more than a handful of distinct microservices, it becomes difficult for every service to know the address of every service it depends on. Configuring dependencies from inside a microservice is impractical – it distributes configuration among all the microservices. It also violates the DRY principle – multiple microservice instances will need access to the same configuration settings. What’s more, it goes against the Dependency Injection design that’s supposed to be one of the benefits of the Microservices Architecture.

The standard solution is to delegate location of microservices to a new microservice. In keeping with the Single Responsibility Principle, this ‘discovery’ microservice is responsible for tracking the locations of all the other microservices and nothing else.

Netflix’s Eureka is an implementation of a discovery server and integration is provided by Spring Boot. Using Spring Boot, we can build a Eureka discovery server and have our microservices register with it.

Tags discovery, eureka, microservice, netflix. ribbon, RestTemplateBuilder, spring boot, spring cloud | Permalink | Comments (8)

Java Technologies Spring Boot Testing

RestTemplateBuilder and @RestClientTest in Spring Boot 1.4.0

July 16, 2016 – 10:16 pm

Spring Boot 1.4.0 is now available. Among the enhancements are new mechanisms to build and test RestTemplates used to make calls to RESTful web services.

Tags jackson, REST, RestClientTest, RestTemplate, RestTemplateBuilder, spring boot | Permalink | Comment (1)