In the Agile software development, continuous and seamless build integration is a requisite criterion for a quality application. Unlike the traditional waterfall development approach, the Agile stipulates that a mature piece of code is developed and delivered at every iteration. This necessitated the practice of ongoing code integration in software engineering. First applied in Extreme Programming, it keeps gaining popularity and has triggered the nascence of various tools for continuous integration (CI) that help development teams merge their results.
The Continuous Integration (CI) Practice
Is it really that important to integrate code continuously if the development is already split into short iterations and errors can be revealed in a timely manner? Indeed, Agile teams must deliver ready pieces of code every cycle, so that they have no room for error. While developers are concentrated on building new features, errors and bugs can intrude the code and cause the software’s poor performance.
That is why there is a generally accepted practice that developers share their output with their peers by integrating it with a common repository several times a day. This rapid code merging reveals issues and aberrations before the end of an iteration so that timely steps can be taken to fix them. CI helps programming teams avoid stepping on one another’s code and prevent integration issues.
Continuous Integration Tools
Many Agile development teams turn to CI solutions, as they not only automate code sharing and merging, but also report if anything has gone wrong. This makes such tools indispensable in preventing a break of a ready build. Also, as these solutions minimize manual testing efforts, they are often considered test automation instruments, because they allow to check the code against a larger code base.
The major advantage of these instruments is that they make a significant contribution to the software quality by the revealing of possible defects earlier for their timely elimination. The users derive the following benefits as well:
- A quick feedback loop
- Improved collaboration within a team
- Reduced risk of code regression
- Version control within various patch and product releases
- Reduced delivery time
- The capability of roll-back if there are some issues with the current build version
Despite all these advantages, one should keep in mind that CI tool’ administration and maintenance come at a price. Also, issues related to testing automation may arise, as not all testers have the required skills.
The Best Continuous Integration Tools
Regardless that various continuous integration testing tools have their own specific features, all of them have a similar structure of embedded automation:
- Code checkup
- Executable file generation and compilation
- Unit testing
- Code deployment
- Integration testing
- Result reporting
Many companies wonder which continuous integration tools for agile software development are the best and why to opt for one instrument instead of another. Indeed, the choice depends heavily on a company’s requirements, available budget and technology stack. That is why continuous deployment tools comparison is a challenging task. However, we compiled the top 5 list of continuous integration tools of those that online source and social network users consider to be the best.
CircleCI is a free hosted tool for code integrating into both a self-hosted repository or into a shared one. It provides the testing of mobile apps (Android and iOS, cross-platform and native) and Rails apps and has the following technical characteristics:
- Integrates with GitHub web-service
- Supports Java, Python, Ruby/Rails, Haskell, Node.js, PHP and Skala languages
- Provides dependencies from Postgres to Docker
- Utilizes PhantomJS and Cucumber
The pricing model is “container”-based; that is, one container is free and allows building scores of projects on it. Adding another container requires payment, but a company can choose the needed parallelization level, from 1x to 16x.
Thousands of leading enterprises use CircleCI, as it ensures fast code delivery and allows their programmers focus on their core competencies. Among the customers are Facebook, Shyp, Kickstarter and Spotify.
Another top-ranked integration solution, Codeship is a shareware that provides a free trial package narrowed to 5 projects and 100 builds per month and allows adding Docker on a fee basis. Also, a custom plan is available for companies that seek to fully adjust the tool to their requirements.
Codeship’s key features are that it:
- Integrates with Bitbucket and GitHub web-services
- Supports Python, Ruby/Rails, Java, PHP, Go and Node.js languages
- Can be deployed on Heroku and AWS platforms
- Allows for having more than one account per repository
In Codeship, the developers fixed the issues CircleCI had, so the repository owner can now preload environment variables into the system.
This open source CI instrument is in strong demand, as it provides a unique combination of the following attributes:
- Cloud hosting
- Full support
- Free-of-charge basis for public repositories
The solution can be hosted on both companies’ own servers and on GitHub, the latter free of charge. However, the range of companies that opt for Travis is limited to those that use public repositories, as it doesn’t support commercial ones.
Jenkins is a cross-platform CI tool that was created after Oracle acquired Sun Microsystems. Now Jenkins is probably the most popular cross-platform solution because of its free-of-charge basis and high configurability and customization. It allows the extension of test features through multiple plugins, both via console commands and GUI interface. Also, Jenkins allows developing custom plugins.
Besides the superior extensibility, the capability to distribute ready builds on several devices distinguishes this tool. Also, it supports a variety of tools for source code management, such as Git, Clearcase and more. In its performance, Jenkins focuses on continuous software development and testing and on the monitoring of external jobs.
However, on the minus side, Jenkins’ user interface is outdated. Also, the absence of performance issues on the server is required for Jenkins’ seamless maintenance.
A servlet container-based continuous integration tool, TeamCity has evolved into a well-established CI server that provides all features in a free package. However, its free version is narrowed to three build agents and 20 configurations, while additional ones are fee-based. For the solution’s feature extension, a company may purchase multiple open source plugins.
TeamCity’s out-of-the-box version supports a variety of frameworks and tools and an especially large number of .NET features. This makes Java-based TeamCity the top choice for .NET projects.
Tool Number One
Naturally, the number of continuous integration tools is not limited to these five solutions. While the choice of an instrument generally depends on available resources and business requirements, a company should first decide on a hosted or a cross-platform one. The majority of programming teams turn to hosted tools as they allow focusing on software development and testing instead of maintaining the infrastructure that supports it. At the same time, locally installed CI tools provide full control over the IT infrastructure and higher security to key environment variables.