GitLab CI vs Jenkins: Choosing the Best CI/CD Platform in 2023

If you‘re looking to accelerate software delivery through automation, implementing a CI/CD pipeline is essential. And two open source tools dominate the continuous integration and delivery landscape – GitLab CI and Jenkins.

But between feature-packed GitLab touting an integrated approach and the battle-tested flexibility of Jenkins, how do engineering leaders choose? Let‘s compare these platforms in-depth so you can make the right CI/CD decision for your organization.

Why Continuous Integration and Delivery Matters

First, what do we mean by continuous integration and delivery?

Continuous integration (CI) refere to the practice of frequently merging developer code changes into a shared code repository multiple times per day. Each integration triggers an automated build and test process to catch issues early.

Continuous delivery and deployment (CD) takes integration a step further by ensuring these code changes can be reliably released to users. CD relies on consistent automated testing and deployment to production environments.

Implementing CI/CD practices leads engineering teams to tighter iteration cycles and faster innovation. Developer satisfaction also sees a boost – a DORA 2021 study found elite performers using CI/CD were able to resolve critical production issues in under an hour.

But to reap these rewards, organizations need a robust CI/CD foundation. That‘s where GitLab and Jenkins come in.

Quick History of GitLab CI and Jenkins

Before comparing features, let‘s look at where each of these tools originated.

Jenkins traces its history back to Hudson – an open source Java-based CI server started in 2004. After an internal dispute, the Hudson community forked the project into Jenkins in 2011. After more than 15 years supporting mission-critical pipelines across industries, Jenkins remains an industry standard.

GitLab CI emerged far more recently in 2014 as a native continuous integration component built directly into GitLab alongside code hosting capabilities. GitLab itself launched two years earlier in 2012 as an open source alternative to GitHub and other code repositories.

Thanks to its integrated approach, GitLab CI adoption has steadily grown, especially among digital native companies.

Adoption and Usage Statistics

In terms of real-world usage, Jenkins enjoys incredible popularity with over 300,000 active installations as of 2022. Globally, an estimated 30% of computer programmers rely on Jenkins for CI/CD needs according to SlashData.

While harder to precisely track as a built-in GitLab module, G2 estimates over 13,000 companies actively use GitLab CI based on over 18,000 Glassdoor reviews referencing the CI/CD component.

Regardless of which platform edges ahead in totals, both Jenkins and GitLab CI undoubtedly make up a massive portion of the CI/CD market supporting millions of developers daily.

Architectural Differences

One of the biggest contrasts between both platforms comes down to underlying architecture and infrastructure requirements.

Jenkins employs a master/slave architecture. The centralized Jenkins controller handles scheduling build jobs. It then delegates actual execution onto dynamically provisioned agent nodes. Agents auto-register with the master to process demanding workloads like compiling code, executing tests and managing deployments.

This separation of concerns provides Jenkins immense flexibility. Teams can scale workloads by spinning up more agents on existing infrastructure or autoscaling onto clouds. Configuring specific agents to handle particular jobs also helps manage pipelines efficiently. Jenkins‘ architecture ensures that even at massive scales, the controller remains lightweight and responsive.

GitLab CI follows a more straightforward architecture consisting mainly of GitLab‘s web application and GitLab CI runners. These special processes execute the jobs defined in .gitlab-ci.yml files stored alongside repository source code.

Unlike Jenkins agents, runners do not auto-register with a central master. Teams must manually configure each runner agent and register them to handle projects as needed. Rather than decoupling the coordinating and build execution responsibilities, GitLab combines everything into a single application.

This simplicity eases setup and management for small teams. But sustaining performance at scale places a heavier burden directly on GitLab application instances and beefier runners. Scaling GitLab CI demands upgrading GitLab server specs and runners in parallel.

Pipeline Configuration Approaches

Another key difference comes in how pipelines get defined and configured through code.

Jenkins adopted a "configuration as code" approach early on with the Jenkinsfile. This simple text file uses a Groovy-based domain specific language (or optionally YAML) to script out all the stages, triggers, execution logic and environmental controls of a pipeline.

Jenkinsfiles exist separately from application codebases allowing teams to define pipelines how they see fit. Jenkins also supports configuring sequential jobs with inputs, outputs and dependencies via its browser-based UI.

GitLab CI utilizes a .gitlab-ci.yml file checked directly into the associated code repository under the root directory. Instead of proprietary DSLs, this pipeline definition leverages familiar YAML syntax.

Stashing configs alongside code in version control provides syncing and single source of truth benefits. But YAML‘s limited constructs can make complex pipelines harder to orchestrate in GitLab out of the box.

In practice, YAML tends to allow faster starts while Jenkinsfiles/scripting adds advanced flexibility.

Ease of Use

With software complexity always increasing, ease of use remains a key consideration when evaluating enterprise platforms like CI/CD tools.

GitLab CI offers a smoother initial onboarding experience compared to Jenkins. YAML syntax lowers the initial learning curve for codifying pipelines compared to Groovy scripting. The entirely web-based UI also streamlines configuration versus Jenkins‘ fragmented browser and terminal efforts.

Integrating directly inside the full GitLab product also means developers don‘t need to context switch between systems. Unified authentication, permissions and interfaces makes GitLab feel like a consistent DevOps solution rather than a mix of distinct tools.

Jenkins provides unparalleled customization for those willing to master the intricacies. But getting oriented as a beginner can pose challenges even for seasoned developers. Steeper learning curves lead to longer time-to-value and greater dependency on elusive tribal knowledge.

The breadth of plugins available does let teams simplify Jenkins once customized to their needs though.

Plugin Ecosystem & Integrations

A key strength fueling rapid Jenkins adoption over the years comes from its extensive community integrations. Developers worldwide have contributed over 1,800 plugins that snap easily into Jenkins through its modular architecture.

This vast library of extensions allows interfacing Jenkins with practically every major DevOps tool like Docker, Kubernetes, Terraform, AWS and more. Teams rely on Jenkins‘ plugins for security, notifications, software integrations, and even UIs. Plugins enable custom-tailoring pipelines to each organization‘s unique needs.

GitLab CI offers a smaller set of built-in integrations centered mainly around the GitLab ecosystem. The Auto DevOps component does provide application templating, best practice guidance and automation for getting workloads deployed onto Kubernetes just by committing code.

While convenient at first, this closed-loop approach ultimately limits what you can accomplish as teams mature. GitLab CI provides streamlining when sticking to very standardized workflows but less flexibility otherwise.

Scalability

For large engineering organizations and enterprise adopters, reliably scaling CI/CD capacity remains imperative. Both platforms offer proven models for expansion but differ substantially.

Jenkins shines when handling immense pipeline demands. The master/agent segregation ensures workload coordination and execution scales independently. Auto-registration protocols enable instantly spinning up thousands of ephemeral agents. Teams can inject Jenkins jobs onto essentially infinite infrastructure capacity thanks to cloud integration plugins.

Real-world examples like Samsung leveraging over 15,000 Jenkins nodes demonstrate extreme horizontal scale in action. Jenkins‘ architecture means that no matter how many daily builds, tests or deployments – pipelines keep flowing.

GitLab CI traditionally centralized responsibilities onto single servers requiring vertical scaling. Costly overhead from backup runners helps but also adds overhead. Recent releases now allow federating GitLab instances via Global CI Load Balancing. While improving horizonal capacity, coordination still demands beefier servers.

Successfully scaling pipelines ultimately comes down to optimizing runners and keeping within recommended operational thresholds.

While capable of handling substantial throughputs, Jenkins generally operates more efficiently at massives scales compared to GitLab alternatives. This allows Jenkins to power the most demanding enterprise CI/CD workloads globally.

Security

With CI/CD automation touching business-critical systems and code, security ranks high when comparing options. We‘ll briefly outline key considerations.

Since Jenkins serves as a central hub managing pipeline execution, hardening the master server and carefully restricting access is critical. Secure plugin vetting should occur given the dangers posed by third-party extensions. Agents handling sensitive processes also require controls and isolation.

GitLab CI security focuses mainly on the core GitLab application and runners. Access controls need tightening while still enabling developer self-service. Accepting contributions warrant careful review to avoid supply chain attacks impacting the CI/CD stack.

Both solutions provide security-centric features as well but should integrate with existing solutions for encryption, secrets management, SSO authentication and so on. We won‘t dive deeper here but encourage using least privilege principles and other best practices around your CI/CD tools.

Commercial & Managed Options

Jenkins and GitLab both originated as open source projects but offer commercial editions and managed hosting options as well.

Jenkins remains under the stewardship of original Hudson founder Kohsuke Kawaguchi along with support from CloudBees. In addition to open source Jenkins, CloudBees provides several managed Jenkins distributions, enterprise plugins, troubleshooting services, training and more.

Managed CloudBees CI hosting plans provision optimized Jenkins environments on AWS or Google Cloud backing teams of 15+ members. Custom deployments allow running CloudBees CI on private infrastructure as well for air-gapped security.

GitLab offers its CI/CD capabilities in open source as a component of the broader GitLab product suite. GitLab Inc. sells subscriptions primarily targeting large organizations that unlock features like security scanning, compliance controls and speed improvements in the CI/CD module.

For teams that want to outsource management, GitLab.com delivers GitLab Enterprise Edition pre-installed on public cloud infrastructure. Both self-managed and SaaS options receive professional services to get platforms correctly configured to each organization‘s needs.

Which Organizations Use GitLab CI vs Jenkins?

In addition to feature comparisons, looking at real-world implementations offers helpful perspective.

As the industry standard for many years, Jenkins underpins mission-critical CI/CD pipelines within nearly every major enterprise. The flexible architecture seamlessly integrates alongside homegrown stacks making migration low risk. Wells Fargo, eBay, Uber, Netflix, Reddit, Spotify all stand as Jenkins devotees powering their development ecosystems.

A CloudBees 2022 survey of 800 IT decision makers found 61% actively use Jenkins while 25% more plan to within a year. 85% agree Jenkins improves software quality – validating its reputation.

GitLab CI tends to see heavier adoption among born-in-the-cloud digital natives with greenfield infrastructure demands. By combining CI/CD capabilities alongside modern code repository management, issue tracking, planning and security tools, GitLab provides growing startups an integrated DevSecOps stack.

High-growth companies like Goldman Sachs, NASDAQ, Sony, IBM,Oracle, CERN, SpaceX, Screwfix and more run their agile development pipelines on GitLab CI according to the official customer page. Its CI/CD solution seamless interconnects with native ChatOps, security scanning and observability data source integrations.

While most headlines focus on newly minted unicorns choosing GitLab, even traditional enterprises often leverage it for digital transformation initiatives around mobile, IoT and machine learning applications built leveraging cloud-native practices.

Expert Guidance on Comparing CI/CD Tools

Beyond just technical capabilities, industry perspectives provide helpful framing. Let‘s review insights from several DevOps thought leaders.

"Jenkins and GitLab aim to serve slightly different needs out of box, but enterprises should consider both tools as part of a comprehensive CI/CD portfolio strategy." – Kaspar Compes, CI/CD Automation Lead at Anduril

"YAML definitely gets you started faster, but Groovy [in Jenkins] is vastly more capable for advanced scripting needs. Fortunately learning fundamentals transfers between both." – Carmen DeArdo, DevOps Consultant/Blogger

"Don‘t assume GitLab CI is inherently easier because of YAML over scripting. Abstraction leaks at scale. Jenkins‘ flexibility, warts at all, better sustains 6-9 digit daily pipelines critical for many industries." – Davis W. Norris, Sr. DevOps Architect at CloudSphere

These experienced practitioners rightly explain that the needs of every software delivery team differ. Before determining GitLab vs Jenkins as an either-or decision, first carefully evaluating your organization‘s requirements, skill sets, applications and infrastructure realities.

In many enterprises, both platforms actually complement each other for different needs as companies standardize CI/CD pipelines. Rather than a single tool solving all challenges, architecting a CI/CD matrix leveraging multiple solutions might work smarter long-term.

Cloud-Native Options: GitLab vs Jenkins vs Argo CD/Tekton

For organizations specifically interested in optimal CI/CD for Kubernetes, third-party cloud-native options also warrant consideration alongside (or on top of) traditional platforms.

Tools like Argo CD specialize in applying GitOps container deployment and promotion practices across environments. Tekton builds specialized Kubernetes-based pipelines embracing declarative principles.

Evaluating these promising upstarts extends beyond our current scope focused just on GitLab vs Jenkins. But understanding the capabilities that such modern options provide and comparing to legacy approaches will grow increasingly relevant in coming years as cloud transformation accelerates.

Which CI/CD Platform Should You Choose?

So with so many insights covered, how do technology leaders decide on Jenkins vs GitLab CI? Or incorporate both into broader strategies?

Here is a quick decision guide:

When to Choose GitLab CI:

  • You want CI/CD integrated natively into a complete DevOps platform
  • Your team finds YAML easier to work with than pipeline scripting
  • You don‘t need a high level of customization or third-party integrations
  • Your pipeline workloads are relatively small to medium complexity

When to Choose Jenkins:

  • You have specific infrastructure requirements not supported by GitLab’s architecture
  • Your organization requires intricate CI/CD pipelines and customization
  • Enterprise-scale, mission-critical or advanced CI/CD capabilities are required
  • Budget is highly constrained and you only require pure CI/CD functionality
  • Your team prefers writing scripts over YAML for pipeline portability

And for large enterprises, adopting both platforms is common:

  • Legacy Java applications rely on battle-hardened Jenkins pipelines
  • Greenfield cloud-native apps utilize GitLab CI integrating with Kubernetes
  • Jenkins handles immense scale pipeline coordination
  • GitLab manages modern but less complex CI/CD workflows

Rather than locking into a single solution, modern development organizations employ a CI/CD matrix – leveraging multiple specialist tools where each excels.

Weigh your criteria accordingly – skills, processes, applications, delivery requirements and infrastructure realities. This definitive comparison only marks a starting point for teams to determine an optimal CI/CD fit.

Now armed with a complete picture of Jenkins and GitLab’s respective advantages, technology leaders can architect flexible pipelines tailored to enterprise delivery needs in 2023 and beyond!

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