, a Merging Bot

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You get a GitHub pull request. You review it. It looks correct—it's time to merge it into master. You post a comment in it, asking @rultor to test and merge. Rultor starts a new Docker container, merges the pull request into master, runs all tests and, if everything looks clean—merges, pushes, and closes the request.

Then, you ask @rultor to deploy the current version to production environment. It checks out your repository, starts a new Docker container, executes your deployment scripts and reports to you right there in the GitHub issue.

Master Branch Must Be Read-Only

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Continuous integration is easy. Download Jenkins, install, create a job, click the button, and get a nice email saying that your build is broken (I assume your build is automated). Then, fix broken tests (I assume you have tests), and get a much better looking email saying that your build is clean.

Then, tweet about it, claiming that your team is using continuous integration.

Then, in a few weeks, start filtering out Jenkins alerts, into their own folder, so that they don't bother you anymore. Anyway, your team doesn't have the time or desire to fix all unit tests every time someone breaks them.

After all, we all know that unit testing is not for a team working with deadlines, right?

Wrong. Continuous integration can and must work.

Liquibase with Maven

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Liquibase is a migration management tool for relational databases. It versionalizes schema and data changes in a database; similar to the way Git or SVN works for source code. Thanks to their Maven plugin, Liquibase can be used as a part of a build automation scenario.

How to Read MANIFEST.MF Files

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Every Java package (JAR, WAR, EAR, etc.) has a MANIFEST.MF file in the META-INF directory. The file contains a list of attributes, which describe this particular package. For example:

Manifest-Version: 1.0
Created-By: 1.7.0_06 (Oracle Corporation)
Main-Class: MyPackage.MyClass

When your application has multiple JAR dependencies, you have multiple MANIFEST.MF files in your class path. All of them have the same location: META-INF/MANIFEST.MF. Very often it is necessary to go through all of them in runtime and find the attribute by its name.

jcabi-manifests makes it possible with a one-liner:

import com.jcabi.manifests.Manifests;
String created ="Created-By");

Custom Pygments Lexer in Jekyll

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I needed to create a custom syntax highlighting for on which I'm using Jekyll for site rendering.

This is how my code blocks look in markdown pages:

{ % highlight requs %}
User is a "human being."
{ % endhighlight %}

I created a custom Pygments lexer:

SASS in Java Webapp

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SASS is a powerful and very popular language for writing CSS style sheets. This is how I'm using SASS in my Maven projects.

First, I change the extensions of .css files to .scss and move them from src/main/webapp/css to src/main/scss.

Then, I configure the sass-maven-plugin (get its latest versions in Maven Central):


XML+XSLT in a Browser

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Separating data and their presentation is a great concept. Take HTML and CSS for example. HTML is supposed to have pure data and CSS is supposed to format that data in order to make it readable by a human. Years ago, that was probably the intention of HTML/CSS, but in reality it doesn't work like that. Mostly because CSS is not powerful enough.

We still have to format our data using HTML tags, while CSS can help slightly with positioning and decorating.

On the other hand, XML with XSLT implements perfectly the idea of separating data and presentation. XML documents, like HTML, are supposed to contain data only without any information about positioning or formatting. XSL stylesheets position and decorate the data. XSL is a much more powerful language. That's why it's possible to avoid any formatting inside XML.

The latest versions of Chrome, Safari, Firefox and IE all support this mechanism. When a browser retrieves an XML document from a server, and the document has an XSL stylesheet associated with it—the browser transforms XML into HTML on-fly.

Deploy Jekyll to GitHub Pages

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This blog is written in Jekyll and is hosted at GitHub Pages. It uses half a dozen custom plugins, which are not allowed there.

Here is how I deploy it:

$ jgd

That's it. jgd is my Ruby gem (stands for "Jekyll GitHub Deploy"), which does the trick. Here is what it does:

CasperJS Tests in Maven Build

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I'm a big fan of automated testing in general and integration testing in particular. I strongly believe that effort spent on writing tests are direct investments into quality and stability of the product under development.

CasperJS is a testing framework on top of PhantomJS, which is a headless browser. Using CasperJS, we can ensure that our application responds correctly to requests sent by a regular web browser.

Limit Java Method Execution Time

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Say, you want to allow a Java method to work for a maximum of five seconds and want an exception to be thrown if the timeframe is exceeded. Here is how you can do it with jcabi-aspects and AspectJ:

public class Resource {
  @Timeable(limit = 5, unit = TimeUnit.SECONDS)
  public String load(URL url) {
    return url.openConnection().getContent();