Continuous integration best practices
Continuous Integration (CI) is a software development practice where developers frequently integrate code into a shared repository, triggering automated builds and tests to detect issues early.
It’s much easier to fix small problems than big problems, as a general rule. One of the biggest advantages of continuous integration is that code is integrated into a shared repository against other changes happening at the same time. If a development team commits code changes early and often, bugs are easier to identify because there is less code to sort through.
By testing in small batches, code quality is improved and teams can iterate more effectively.
Continuous integration systems make documentation widely available, and this documentation can be very helpful long after you’ve implemented CI into your workflow. At GitLab, we have thorough CI/CD documentation that is updated frequently to reflect the latest processes.
In can be helpful to reference the documentation in READMEs or in other accessible formats. Encourage team members to read the documentation first, bookmark links, create FAQs, and incorporate these resources into onboarding for new team members.
CI pipelines contain jobs and stages: Jobs are the activities that happen within a particular stage, and once all jobs pass, code moves to the next stage. To get the most out of your CI pipelines, optimize stages so that failures are easy to identify and fix.
Stages are an easy way to organize similar jobs, but there may be a few jobs in your pipeline that could safely run in an earlier stage without negatively impacting your project if they fail. Consider running these jobs in an earlier stage to speed up CI pipelines.
Nothing slows down a pipeline like complexity. Focus on keeping builds fast, and the best way to do that is by keeping things as simple as possible.
Every minute taken off build times is a minute saved for each developer every time they commit. Since CI demands frequent commits, this time can add up. Martin Fowler discusses a guideline of the ten-minute build that most modern projects can achieve. Since continuous integration demands frequent commits, saving time on commit builds can give developers a lot of time back.
Improvement is a process. When teams change their response to failures, it creates a cultural shift for continuous improvement. Instead of asking who caused the failure, ask what caused the failure. This means shifting from a blaming culture to a learning culture.
If teams are doing frequent commits, it becomes much easier to identify problems and solve them. If there are patterns in failed builds, look at the underlying causes. Are there non-code errors that are causing builds unnecessarily? Maybe incorporate an allow_failure
parameter. Look for ways to continually improve, make failures blameless, and look for causes (not culprits).
In continuous integration, every commit triggers a build. These builds then run tests to identify if something will be broken by the code changes you introduce. The test pyramid is a way for developers to think of how to balance testing. End-to end testing is mostly used as a safeguard, with unit testing being used most often to identify errors. One important thing to keep in mind with testing is the environment. When the testing and production environments match, it means that developers can rely on the results and deploy with confidence.
In GitLab, Review Apps put the new code into a production-like live environment to visualize code changes. This feature helps developers assess the impact of changes.
Continuous integration helps developers deploy faster and get feedback sooner. Ultimately, the best continuous integration system is the one you actually use. Find the right CI for your needs and then incorporate these best practices to make the most of your new CI workflow.
By embracing the outlined best practices, software development teams, including platform engineering teams and DevOps teams, can enhance their continuous integration efforts, ultimately streamlining their development and deployment process. As these practices become more embedded in your development environment, the alignment between engineering team goals and operational execution sharpens.
Remember, the strongest continuous integration system is not just about the tools, but about how effectively your team utilizes them to foster improvements and achieve rapid, reliable results.
Frequently Asked Questions
Frequently Asked Questions
The most important CI best practice is to commit early and commit often. Small problems are easier to fix than big problems, and frequent commits make bugs easier to identify because there's less code to sort through. Testing in small batches improves code quality and helps teams iterate more effectively.
Teams should organize similar jobs into stages and consider moving jobs that can safely run earlier without negatively impacting projects. Once all jobs in a stage pass, code moves to the next stage. Optimizing stages makes failures easier to identify and fix while speeding up overall pipeline performance.
The ten-minute build guideline, discussed by Martin Fowler, suggests most modern projects can achieve builds within ten minutes. This matters because every minute saved on build times multiplies across all developers and commits. Since CI demands frequent commits, reducing build time gives developers significant time back.
Teams should shift from asking "who caused the failure" to "what caused the failure," moving from a blaming culture to a learning culture. Look for patterns in failed builds and examine underlying causes. Consider incorporating allow_failure parameters for non-critical errors and make failures blameless learning opportunities.
When testing and production environments match, developers can rely on test results and deploy with confidence. Every commit triggers builds that run tests to identify potential breaks from code changes. GitLab's Review Apps demonstrate this by putting new code into production-like live environments to visualize changes.
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