Knapsack Pro

Gitlab CI vs Jenkins comparison of Continuous Integration servers
What are the differences between Gitlab CI and Jenkins?

Gitlab CI

https://about.gitlab.com/product/continuous-integration/

Jenkins

https://jenkins.io
Unique feature

AutoDev Ops / Allows keeping code management and CI in the same place

Plugins

Type of product

SaaS / On Premise

Self-hosted / On Premise

Offers a free plan

Yes

Very generous free plans for both the SaaS version as well as the on premise version.

Yes

Free, open source software

Predictable pricing

Yes

Clear and affordable pricing for both SaaS and self-hosted versions.

Yes

Jenkins is free software, the only costs are those assigned to running your infrastructure.

Support / SLA

Yes

All paid plans include next business day support.

No (partial)

No official support available, or SLAs. However, Jenkins' popularity ensures you'll find support in various places (official Jenkins forum, IRC, StackOverflow etc.)

Paralellism
Every CI servers tends to address this differently (parallel, distributed, build matrix). Some of it is just marketing, and some is just nuance. For this table, parallel means that tasks can be run concurrently on the same machine, distributed means that tasks can be scaled horizontally, on multiple machines
How to split tests in parallel in the optimal way with Knapsack Pro

Yes

Easily configure jobs you want to be run in parallel via the YML config file (gitlab-ci.yml)

Yes (partial)

Jenkins allows builds to be run in parallel, but all builds share the same environment and there can be issues arising from shared resources such as the filesystem.

Distributed builds
distributed means that tasks can be scaled horizontally, on multiple machines
How to split tests in parallel in the optimal way with Knapsack Pro

Yes

Yes (partial)

Jenkins has a concept of master server and agents, for distributing builds, but setting that up requires quite a bit of manual work from a sysadmin, compared to other options.

Containers support / Build environment

Yes

The Docker Container Registry is integrated into GitLab by default

No (partial)

By default, Jenkins runs all builds in the same environment as the build server itself, which can lead to numerous issues and is generally not a good practice. Some plugins address this issue, but they need to be manually installed.

Analytics / Status overview
Analytics and overview referrs to the ability to, at a glance, see what's breaking (be it a certain task, or the build for a specific project)

Yes

Yes

Available via the Blue Ocean project (part of Jenkins): https://jenkins.io/doc/book/blueocean/dashboard/#dashboard

Management support
How easy is it to manage users / projects / assign roles and permissions and so on

Yes

No

In practice, for Jenkins it usually means that there's someone solely in charge of the Jenkins instance (configuration, management). Collaboration features built into other similar products are lacking, as are governance features (no easy way to tell from Jenkins alone _who_ is responsabile for a broken build, for example), even if your Version Control Server of choice can give that information (via `git blame` for example).

Self-hosted option

Yes

Yes

Jenkins is Open Source Software, and self-hosting is the only way to use it.

Hosted plans / SaaS

Yes

No

Only available for self-hosting.

Build pipelines
A continuous delivery pipeline is a description of the process that the software goes through from a new code commit, through testing and other statical analysis steps all the way to the end-users of the product.

Yes

Defined via YML config files

Yes

Offers extensive support for custom pipelines, either through the Jenkins Pipeline DSL, written in a Jenkinsfile, either through the Web UI. Also, their Blue Ocean project is a great tool for building pipelines: https://jenkins.io/projects/blueocean/

Reports
Reports are about the abilty to see specific reports (like code coverage or custom ones), but not necesarily tied in into a larger dashboard.

Yes

Yes

Has ready-made integrations for standard reports such as JUnit test results.

Ecosystem
Besides the official documentation and software, is there a large community using this product? Are there any community-driven tools / plugins that you can use?

Yes

> 1000 community plugins

Thanks to it's popularity, there's a large selection of available plugins for Jenkins. They can all be easily browsed over at https://plugins.jenkins.io/. The downside is that almost anything you want to do in Jenkins requires installing a plugin, even core functionality such as parsing output or checking out source code.

Specific language support: Ruby
Some CI servers have built-in support for parsing RSpec or Istanbul output for example and we mention those. Some others make it even easier by detecting Gemfiles or package.json and automate parts of the process for the developer.

Yes

Although not built into GitLab CI by default, the Docker support allows solving any Ruby specific need that may arise.

Yes (Partial)

RSpec and Cucumber test suites can be integrated into Jenkins thanks to the large pool of available plugins and Ruby gems. Jenkins only understands the JUnit format natively.

Specific language support: JavaScript

Yes

Although not built into GitLab CI by default, the Docker support allows solving any Javascript specific need that may arise.

Yes (Partial)

Jest, AVA and other test suites can be integrated into Jenkins thanks to the large pool of available plugins and NPM packages. Jenkins only understands the JUnit format natively.

Integrations
1st party support for common tools (like Slack notifications, various VCS platforms, etc)

Yes

Plenty of third party integrations available throughout GitLab, most notably Kubernetes and GitHub, but also plenty of others: https://docs.gitlab.com/ee/integration/README.html

Yes

Allows integrations with other tools (ie: Slack, GitHub) or communication protocols (ie: email) via it's rich plugin suite

API
Custom integreation is available, via an API or otherwise, it's mentioned separately as it allows further customization than any of the Ecosystem/Integration options

Yes

Provides a REST API and a (new) GraphQL API, with plans to maintain the GraphQL API only going forward. Allows doing almost anything that can be done via the interface, at least in terms of CI needs.

Yes

For use-cases that the +1k plugins don't cover, the Jenkins Remote API is yet another way to integrate Jenkins into your favorite tools or internal products.

Auditing

Yes

No

Jenkins instances are really managed by a sole user with administrative privileges. This can lead to various issues when it comes to audit trails / accountability.

Additional notes

The Auto DevOps feature might be interesting to people looking for a very hands-off experience with getting a CI/CD process up and running https://docs.gitlab.com/ee/topics/autodevops/

GitLab CI parallelisation - how to run parallel jobs for Ruby & JavaScript projects

Continuous delivery pipelines in Jenkins and CI parallelisation

Gitlab CI parallelism integration

Jenkins parallelism integration

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