Build Environments
CircleCI lets you customize the execution environment to match the needs of your software, using any Docker image, a Linux VM, or a macOS VM. Whether you’re building a website, a multi-platform mobile app, or systems software, CircleCI gives you a clean, customizable environment for every job.
Run your jobs in any Docker image
Each job on CircleCI can specify any Docker image as the runtime environment, including support for private images. Use one of our (pre-built images for most popular languages) or use your own image hosted on Docker Hub or other accessible registry.
Learn More 
-
Public or private images
Pull any public image or add authentication credentials to run jobs in your own private images.
-
Support for all common registries
Supports most common registries including Docker Hub, Google Container Registry, CoreOS Quay, and Amazon ECR.
Run any job in a fresh Ubuntu virtual machine
CircleCI provides a set of pre-configured VMs with different versions of Docker and a host of common tooling pre-installed.
Learn More
-
Pre-provisioned, fresh every time
Avoid VM spin-up time and get a clean environment for every job. Optional ability to cache and reuse the contents of your VM across jobs.
-
Full Docker CLI support
Avoid the “Docker in Docker” difficulties and run your `docker` commands in a VM to build and push your images as part of a job.
-
Includes Android App development
You can automatically build and test your changes for your Android app each time you push new code to your repo on GitHub or Bitbucket. More testing equals fewer bugs.
Efficiently build and test Android apps
Building and testing an Android app isn't easy. CircleCI helps you build and test your Android apps quickly. Avoid 1-star reviews by ensuring that your apps are bug-free the first time.
Learn More
-
Get started quickly
CircleCI preinstalls the Android SDK, a number of SDK packages, and the NDK, so you don't have to.
-
Testing made easy
Easily set up the Android emulator.
Develop for all Apple devices
Gain the flexibility and control you need to run your Xcode projects efficiently. Run macOS jobs on the same config as your Linux or Android projects. Determine Xcode versions on any job and run an endless combination of Workflows.
Learn More
-
Multi-OS output
Build and test any Apple app for macOS, iOS, tvOS, or watchOS
-
Run jobs on any Xcode version
CircleCI makes it easy to keep-up with Apple’s updates and ensure dependencies are up to date.
-
Flexibility and control with Workflows
Run jobs in any combination to match your development process.
