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Crossplane CNCF Sandbox Proposal

Name of project

Crossplane

Project description

Introduction

Crossplane is a Kubernetes add-on used to extend and enhance clusters so users can provision and manage infrastructure, managed services, and applications using kubectl, GitOps, or any tools that can talk with the Kubernetes API. With Crossplane, cloud or on-prem infrastructure is represented as a CRD that is configured using YAML and deployed into a cluster alongside existing application configuration. Whether you're using a managed Kubernetes service or self hosting Kubernetes, Crossplane can be installed into your cluster.

Crossplane empowers users to define, compose, and publish their own infrastructure abstractions with declarative YAML on top of the base infrastructure CRDs resulting in new abstracted infrastructure CRDs. With these abstractions, Crossplane lets you put in place policy guardrails to hide infrastructure complexity from applications.

Crossplane supports application definition models allowing users to standardize on a single workflow for both application and infrastructure deployment. The first specification Crossplane supports is the Open Application Model (OAM) originally created by Alibaba and Microsoft. The OAM and Crossplane communities have collaborated on a new version of the OAM specification that unifies the Crossplane and OAM approaches to managing infrastructure and applications by fully embracing Kubernetes-based runtimes. Crossplane also has great support for the native Kubernetes application model with deployments and pods.

With this updated specification in place, Microsoft and Alibaba have joined the Crossplane community and Crossplane is now the Kubernetes implementation of the Open Application Model.

Crossplane functionality can be summarized by 3 main areas that will be covered in more detail in the sections below:

  1. Provision and manage any cloud infrastructure using the Kubernetes API
  2. Publish abstract infrastructure resources as Kubernetes API types (CRDs)
  3. Run and deploy applications alongside infrastructure

Provision and Manage Cloud Infrastructure & Services

Crossplane extends Kubernetes with infrastructure provisioning and management capabilities. Crossplane Providers include CRDs and controllers that operate on cloud provider APIs (GCP, AWS, Azure, Alibaba) and on-prem infrastructure alike. Infrastructure configurations can be authored with idiomatic Kubernetes YAML, versioned and managed with GitOps workflows, and provisioned manually with kubectl or any tool that talks with the Kubernetes API.

Publishing Custom Infrastructure Resources as Kubernetes API types

Crossplane also allows you to author YAML to define, compose, and publish your own composite infrastructure resources on top of the infrastructure primitives included. Complex infrastructure configurations, including policy guardrails, can be hidden behind your own infrastructure resources, resulting in a layer of infrastructure resources that can be consumed dynamically and safely by applications.

A practical example of this is an infrastructure owner wanting to provide a MySQL database to their application developer teams and ensure that it is configured with secure networking connectivity and according to their company policies and practices, without the developers needing to know any of those complicated details.

With Crossplane, custom infrastructure resources can be authored with YAML (no code) that composes the Crossplane CRDs for a managed service database (e.g., Amazon RDS), security groups, networking configuration, and firewall rules. All of this gets published as a new CRD that users can provision alongside their existing application configurations. The end result is secure and compliant infrastructure that is created the same way the application itself is.

This also enables scenarios for multi-cloud abstractions, and creating an internal service catalog of approved services and resources that applications can consume.

Run and Deploy Applications Alongside Their Infrastructure

The Crossplane and OAM communities share a team-centric philosophy and believe a strong separation of concerns combined with the proven Kubernetes declarative model is the best way to manage infrastructure and cloud native applications.

Teams can publish infrastructure resources for applications to consume, define application components independent of infrastructure, and compose both into a complete application configuration -- all using idiomatic Kubernetes YAML that can be deployed with kubectl from app delivery pipelines or with GitOps workflows.

Crossplane support for the new version of the OAM specification enables you to use Crossplane and OAM together by installing the Crossplane helm chart into any Kubernetes cluster.

Origin and History

The Crossplane project was first conceived in November 2017 by the same engineers that created Rook, another CNCF project that has matured and is currently under consideration for graduation. Within the Rook project, we saw firsthand the benefits Kubernetes provided for storage resources from the Volume abstraction. This was a first glimpse at application developers declaring and managing infrastructure (storage volumes) alongside and in the same way they were configuring their applications. We quickly saw that the benefits from this approach could be applied to many more types of infrastructure beyond just volumes, such as databases, buckets, caches, clusters, etc.

A small team within Upbound worked on the initial concepts, architecture, controllers, CRDs, and documentation and made the first public v0.1 release on December 4th, 2018. The project has grown steadily since then and has continued to gain traction with early adopters as well as some cloud providers. Of significant note is the recent collaboration with Alibaba and Microsoft to support the Open Application Model and standardize the way applications and infrastructure are declared and managed. The project has also been integrated into GitLab to drive auto-devops workflows on multiple cloud providers.

Crossplane has released multiple new versions of the project’s software and has most recently released version v0.11.0.

Statement on alignment with CNCF charter mission

The Crossplane project is well aligned with the CNCF’s charter and mission of making cloud native computing ubiquitous. Crossplane follows the same API-centric, declarative configuration and automation approach pioneered by Kubernetes, and extends it past application orchestration to all the infrastructure and services applications need. The end result is users are now able to unify application orchestration and infrastructure management around the same tooling and processes.

Crossplane enables best in class infrastructure and services of the cloud to be offered directly to cloud native applications regardless of where they run. With Crossplane, it doesn’t matter if your applications run in the cloud or on-prem, the project gives them the resources they need to run and scale in modern, dynamic environments. Furthermore, they can be deployed and consumed in a common way with existing tools and familiar patterns from the ecosystem.

Crossplane is completely open source (Apache 2.0 license) and follows an open governance, in order to foster and sustain a community of broad collaboration and progress across the entire ecosystem in a vendor-neutral and agnostic way. The patterns and innovations of Crossplane that are helping to make cloud native computing more ubiquitous are also accessible for everyone.

Comparison with similar projects (inside or outside the CNCF), including what differentiates this project

While there are many projects that address similar issues, none of them encapsulate the full use case that Crossplane addresses. This list is not exhaustive and is not meant to provide a deep analysis of the following projects, but instead to motivate why Crossplane was created.

Open Service Broker and Service Catalog

The Open Service Broker and the Kubernetes Service Catalog are able to dynamically provision cloud services from Kubernetes. As a result it shares similar goals with Crossplane. However, service broker does not have the ability to define, compose, and publish your own infrastructure resources to the Kubernetes API in a no-code way. Crossplane goes further by enabling infrastructure operators to hide infrastructure complexity and include policy guardrails, with a team-centric approach and a strong separation of concerns, so applications can easily and safely consume the infrastructure they need, using any tool that works with the Kubernetes API. Solutions like the GCP implementation of Open Service Broker have been deprecated in favor of a more Kubernetes-native solution, but one that is Google-specific and closed source. Unlike the Kubernetes Service Catalog, Crossplane is implemented completely as Kubernetes controllers and does not require an external service broker to operate.

GCP Config Connector

The GCP Config Connector is the GCP replacement for Open Service Broker, and implements a set of Kubernetes controllers that are able to provision managed services in GCP. It defines a set of CRDs for managed services like CloudSQL, and controllers that can provision them via their cloud APIs. It is similar to Crossplane in that it can provision managed services in GCP. Crossplane goes further by enabling you to provision managed services from any cloud provider and the ability to define, compose, and publish your own infrastructure resources in a no-code way. Crossplane supports a team-centric approach with a strong separation of concerns, that enables applications to easily and safely consume the infrastructure they need, using any tool that works with the Kubernetes API. GCP Config Connector is closed-source and only supports GCP resources.

AWS Service Operator

The AWS Service Operator is a recent project that implements a set of Kubernetes controllers that are able to provision managed services in AWS. It defines a set of CRDs for managed services like DynamoDB, and controllers that can provision them via AWS CloudFormation. It is similar to Crossplane in that it can provision managed services in AWS. Crossplane goes further by enabling you to provision managed services from any cloud provider and the ability to define, compose, and publish your own infrastructure API types in Kubernetes in a no-code way. Crossplane supports a team-centric approach with a strong separation of concerns, that enables applications to easily and safely consume the infrastructure they need, using any tool that works with the Kubernetes API.

AWS CloudFormation, GCP Deployment Manager, Azure Resource Manager and Others

These products offer a declarative model for deploying and provisioning infrastructure in each of the respective cloud providers. They only work for one cloud provider, are generally closed source, and offer little or no extensibility points, let alone being able to extend the Kubernetes API to provide your own infrastructure abstractions in a no-code way. We have considered using some of these products as a way to implement resource controllers in Crossplane. These projects use an Infrastructure as Code approach to management, while Crossplane offers an API-driven control plane.

Terraform and Pulumi

Terraform and Pulumi are tools for provisioning infrastructure across cloud providers. It offers a declarative configuration language with support for templating, composability, referential integrity and dependency management. Terraform can declaratively manage any compatible API and perform changes when the tool is run by a human or in a deployment pipeline. Terraform is an Infrastructure as Code tool, while Crossplane offers an API-driven control plane. Terraform can be used on-top of Crossplane using the standard Kubernetes terraform provider.

Sponsor from TOC

Sponsors from the TOC will be added as they are confirmed.

Preferred maturity level

Sandbox

License

Apache 2: https://github.com/crossplane/crossplane/blob/master/LICENSE

Source control

The Crossplane project is composed of multiple source code repositories, all of which are hosted on Github under the crossplane organization: https://github.com/crossplane

The core repository can be found at https://github.com/crossplane/crossplane. A library of reusable logic and interfaces that almost all controllers in the Crossplane logic depend on can be found in https://github.com/crossplane/crossplane-runtime.

Some implementations of specific providers are also hosted in the Crossplane organization:

External dependencies (including licenses)

All dependencies (internal and external) of all projects in the Crossplane organization can be found in the Bill of Materials (BOM) and Audit/Due Diligence report. All licensing data has been discovered and analyzed by FOSSA. All projects in the Crossplane organization pass the FOSSA license scan.

Initial committers (how long working on project, companies they represent)

This list of initial committers represents maintainers of repositories within the Crossplane organization that have write permissions to the respective repositories that they maintain.

Name GitHub First Contribution Organization
Jared Watts jbw976 2018-09-07 Upbound
Bassam Tabbara bassam 2018-09-14 Upbound
Nic Cope negz 2019-01-24 Upbound
Daniel Mangum hasheddan 2019-01-21 Upbound
Muvaffak Onus muvaf 2019-07-15 Upbound
Hongchao Deng hongchaodeng 2020-03-09 Alibaba
Artur Souza artursouza 2020-03-27 Microsoft
Ryan Zhang ryanzhang-oss 2020-04-21 Alibaba
Lei Zhang (Harry) resouer 2020-04-22 Alibaba
Sun Jianbo wonderflow 2020-04-26 Alibaba

Infrastructure requests (CI / CNCF Cluster)

We do not have any specific infrastructure requests at the current time. All CI/CD is currently self hosted using Jenkins and GitHub Actions.

Communication channels (slack, irc, mailing lists)

The official communication channels for the project can be found in the README at https://github.com/crossplane/crossplane/blob/master/README.md#get-involved, but are included here for convenience:

Issue tracker

We prefer to track issues in the same code repository that the issue is relevant to, so each repo under the Crossplane GitHub organization will have its own set of issues. For example, the core Crossplane repo issue tracker can be found at https://github.com/crossplane/crossplane/issues.

Website

The official public facing website can be found at https://crossplane.io/

Release methodology and mechanics

The full release process is described in complete detail in this document: https://github.com/crossplane/crossplane/blob/master/docs/release/release-process.md

Here is a brief summary of the release philosophy and methodology:

Social media accounts

Community size and any existing sponsorship

The following statistics, when related to code repositories, are for the main crossplane repo of https://github.com/crossplane/crossplane.

  • GitHub Stars: 2,120+
  • Container downloads: 1,440,000+
  • Releases: 24
  • Commits: 2,215+
  • Forks: 188+
  • Contributors: 48+ contributors
  • Maintainers: 10 maintainers from 3 organizations
  • Twitter followers: 1,484+
  • Slack members: 610+
  • Youtube subscribers: 215+

Who is currently known to be using the project? Are they using it in production and at what scale?

45PRESS

45PRESS recently started evaluating Crossplane as a control plane powering their internal cloud platform which is already built on Kubernetes. They’re building this platform to quickly, easily, and programmatically provision infrastructure for their customers. Before Crossplane, 45PRESS would have to spin up an environment manually whenever they got a new customer. Thanks to Crossplane, this can be done automatically as users sign up for their services.

Alibaba

Alibaba’s application/serverless platform is fully OAM based. Alibaba collaborated with Crossplane on OAM Kubernetes runtime which is the candidate library for Alibaba’s web scale application/serverless systems both internally and core of public cloud products.

GitLab

GitLab has integrated Crossplane into GitLab ADO so users can easily provision and manage infrastructure from their Kubernetes clusters. Crossplane has been shipped with every GitLab release since version 12.5.

Mastercard

Mastercard is one of the largest credit card processors in the world. Internally, their infrastructure environments span many different clouds and data centers. To unify them all, they’re beginning to deploy Crossplane which will connect to services across clouds and provide teams with a central point of management.

Microsoft

Recently, Microsoft collaborated with the Crossplane community to make Crossplane the Kubernetes implementation of OAM application definition specification. Microsoft uses Crossplane to demo the OAM specification on Kubernetes, showing how applications can be deployed across environments using the OAM traits and scopes supported by Crossplane.

Red Hat

Crossplane recently integrated with the Operator Framework to natively integrate with OpenShift as an alternative to the Open Service Broker API for provisioning, managing, and consuming external services by cloud native applications. Red Hat’s Emerging Technologies group and Upbound did a few Proof of Concept (PoC) validations with the goal of running Crossplane as a fully supported OpenShift Operator installed from the OpenShift Operator Catalog.

Swisscom

Swisscom is a major telecommunications provider in Switzerland. The company's Cloud Lab is evaluating Crossplane to help give them a single interface for provisioning and managing services from public and private cloud infrastructure.

Upbound

Upbound is building their marquee product, Upbound Cloud, using Crossplane. Upbound Cloud is an enterprise grade managed service of Crossplane which layers on top of existing infrastructure and transforms it to an internal cloud platform.

VSHN

VSHN is a leading Swiss company specializing in DevOps, Docker, Kubernetes, OpenShift and 24/7 Cloud Operations. VSHN helps software developers run their apps and is integrating Crossplane into their managed service offering of Kubernetes. With Crossplane, VSHN customers will be able to provision the resources managed by VSHN that their applications need without having to submit a support ticket.

Project logo in svg format

All Crossplane artwork and assets can be found in the artwork repository: https://github.com/crossplane/artwork

The current main project logo in svg format can be found in that artwork repo here: https://raw.githubusercontent.com/crossplane/artwork/master/logo/logo-horizontal-bluetext.svg