What is Gravity
Gravity is an open source tooklit for creating “images” of Kubernetes
clusters and the applications running inside the clusters. The resulting
images are called application bundles and they are just
An application bundle can be used to re-create full replicas of the original cluster in any environment where compliance and consistency matters, i.e. in locked-down AWS/GCE/Azure environments or even in air-gapped server rooms. A bundle can run without human supervision, as a “kubernetes appliance”.
Gravity has been running in production in major financial institutions, government data centers and enterprises. Gravitational open sourced it in the fall of 2018. The Gravity Community Edition is open sourced with an Apache 2.0 license and can be found on Github.
Gravity vs …
There are plenty of Kubernetes distributions out there. Most of them aim to be flexible, general purpose platforms. Gravity has a more narrow focus on compliance and reducing the overhead of managing Kubernetes:
- Gravity clusters are idempotent, i.e. clusters created from the same bundle are always identical. There is no configuration drift over time; no “special snowflakes”.
- Gravity clusters are always “wrapped” with a privileged access gateway called Teleport, which unifies k8s and SSH authentication and keeps a detailed audit log for compliance purposes.
- Gravity includes tools to perform infrastructure validation prior to cluster provisioning. This allows cluster designers to prevent users from installing clusters on infrastructure that does not meet the system requirements.
- Gravity clusters only allow Kubernetes components that have been thoroughly tested by Gravitational Inc for compatibility and stability. These components are called a “Kubernetes Runtime”. Users can pick a Runtime but Gravity does not allow any customization of individual components of Kubernetes.
- Gravity uses Helm charts to package applications. One or mutliple applications can be bundled into a single image.
Who is Gravity for?
We have seen the following primary use cases for using a image-based Kubernetes approach (there may be others):
- Deploying complex SaaS applications into on-premises enterprise environments.
- Managing many idempotent Kubernetes clusters in environments where compliance and security matters. An example would be if you want the same, compliant Kubernetes environment across a variety of organizations or infrastructure environments.
- Environments where autonomous Kubernetes is required, such as large multi-node hardware appliances, production floors, edge deployments, etc.
Anyone who needs Kubernetes best practices out of the box, without having to proactively manage it can benefit from Gravity. It allows you to focus on building your product instead of managing Kubernetes.
An Application Bundle produced by Gravity includes:
- All Kubernetes binaries and their dependencies.
- Built-in container registry.
- De-duplicated layers of all application containers inside a cluster.
- Built-in cluster orchestrator which guarantees HA operation, in-place upgrades and auto-scaling.
- Installation wizard for both CLI and web browser GUI.
A bundle is all one needs to re-create the complete replica of the original Kubernetes cluster, with all deployed applications inside, even in an air-gapped server room.
Remote Access and Compliance
Each cluster provisioned with Gravity includes the built-in SSH/Kubernetes gateway called Teleport. Teleport provides the following benefits:
- One-step authentication which issues credentials for both k8s API and SSH.
- Ability to implement compliance rules like “developers must never touch production data”.
- Ability to grant remote access to the cluster via SSH or via k8s API, even if the cluster is located behind NAT with no open ports.
- Keeps a detailed audit log (including fully recorded interactive sessions)
for all SSH commands and all
kubectlcommands executed on cluster nodes.
Is Gravity Production Ready?
Yes! Even though Gravity was open sourced in September 2018, it started life much earlier, as a component of a larger, proprietary system called Telekube.
Fully autonomous Gravity clusters are running inside of large banks, government institutions, enterprises, etc. Some of the commercial users of Gravity are listed here.
Why did We Build Gravity?
Our mission is to allow software creators to easily share their products with customers without having to convert themselves into software operators.
The original use case for Gravity was to allow Kubernetes applications to be deployed into 3rd party environments, like on-premises datacenters. That’s why Gravity includes features like the built-in, graphical cluster installer, infrastructure validation and a built-in privileged access manager (Teleport) for providing remote support.
These features also resonated with security-minded teams who need to run applications in environments where compliance matters. Gravity clusters are always identical and do not allow any configuration drift over time, which allows cluster designers (aka, Devops or SREs) to “publish” clusters that are approved for production and allow multiple teams within the organization to rapidly scale their Kubernetes adoption without having to become security and Kubernetes experts themselves.
Building from source
Gravity is written in Go. There are two ways to build the Gravity tools from source: by using locally installed build tools or via Docker. In both cases you will need a Linux machine.
Building on MacOS, even with Docker, is possible but not currently supported
$ git clone [email protected]:gravitational/gravity.git $ cd gravity # Running 'make' with the default target uses Docker. # The output will be stored in build/current/ $ make # If you have Go 1.10+ installed, you can build without Docker which is faster. # The output will be stored in $GOPATH/bin/ $ make install # To remove the build artifacts: $ make clean
While the code is open source, we’re still working on updating the documentation to reflect the differences between the proprietary and community/OSS editions of the software. We are also working on providing open source users with pre-built binaries on a regular basis.