Overview

What is Operator SDK? Why should I use it?

What is Operator SDK and why should I use it?

This project is a component of the Operator Framework, an open source toolkit to manage Kubernetes native applications, called Operators, in an effective, automated, and scalable way. Read more in the introduction blog post.

Operators make it easy to manage complex stateful applications on top of Kubernetes. However writing an operator today can be difficult because of challenges such as using low level APIs, writing boilerplate, and a lack of modularity which leads to duplication.

The Operator SDK is a framework that uses the controller-runtime library to make writing operators easier by providing:

  • High level APIs and abstractions to write the operational logic more intuitively
  • Tools for scaffolding and code generation to bootstrap a new project fast
  • Extensions to cover common operator use cases

Workflow

The SDK provides workflows to develop operators in Go, Ansible, or Helm.

The following workflow is for a new Go operator:

  1. Create a new operator project using the SDK Command Line Interface(CLI)
  2. Define new resource APIs by adding Custom Resource Definitions(CRD)
  3. Define Controllers to watch and reconcile resources
  4. Write the reconciling logic for your Controller using the SDK and controller-runtime APIs
  5. Use the SDK CLI to build and generate the operator deployment manifests

The following workflow is for a new Ansible operator:

  1. Create a new operator project using the SDK Command Line Interface(CLI)
  2. Write the reconciling logic for your object using ansible playbooks and roles
  3. Use the SDK CLI to build and generate the operator deployment manifests
  4. Optionally add additional CRD’s using the SDK CLI and repeat steps 2 and 3

The following workflow is for a new Helm operator:

  1. Create a new operator project using the SDK Command Line Interface(CLI)
  2. Create a new (or add your existing) Helm chart for use by the operator’s reconciling logic
  3. Use the SDK CLI to build and generate the operator deployment manifests
  4. Optionally add additional CRD’s using the SDK CLI and repeat steps 2 and 3

Command Line Interface

To learn more about the SDK CLI, see the SDK CLI Reference, or run operator-sdk [command] -h.

Operator capability level

Note that each operator type has a different set of capabilities. When choosing what type to use for your project, it is important to understand the features and limitations of each of the project types and the use cases for your operator.

operator-capability-level

Find more details about the various levels and the feature requirements for them in the capability level documentation.

Kubernetes version compatibility

Each operator-sdk release is tested with a specific version of Kubernetes. This version matches that of kubernetes/kubernetes or client-go that operator-sdk depends on directly, or that generated Operator projects depend on.

In general, client-go’s compatibility matrix will determine whether a particular Kubernetes version is compatible with a particular operator-sdk version or generated Operator project. The following tables contains the canonical way per binary or project type to look up a Y-axis version to plug into the compatibility matrix.

By binary:

Binary Lookup strategy
operator-sdk $ operator-sdk version
ansible-operator $ ansible-operator version
helm-operator $ helm-operator version

By project type (replace ${IMAGE_VERSION} with base image version in your project Dockerfile):

Project type Lookup strategy
Go controller-runtime version (see go.mod)
Ansible $ docker run --entrypoint ansible-operator quay.io/operator-framework/ansible-operator:${IMAGE_VERSION} version
Helm $ docker run --entrypoint helm-operator quay.io/operator-framework/helm-operator:${IMAGE_VERSION} version

OLM version compatibility

Operator SDK officially supports the latest 3 versions of OLM present at the time of a given Operator SDK release. These versions of OLM manifests are packaged with the SDK binary in the form of bindata to support low-latency installations of OLM with operator-sdk olm install. Any other version installed with this command may work but is not tested nor officially supported.

Currently, the officially supported OLM Versions are: 0.16.1, 0.17.0 and 0.18.1.

Platform support

Official build architectures for binaries:

Binary linux/amd64 linux/arm64 linux/ppc64le linux/s390x darwin/amd64 darwin/arm64
operator-sdk -
ansible-operator -
helm-operator -

Official build architectures for images:

Binary linux/amd64 linux/arm64 linux/ppc64le linux/s390x
operator-sdk
ansible-operator
helm-operator
scorecard-test
scorecard-test-kuttl -

Official support for any Windows architecture is not on the roadmap at this time.

Samples

To explore any operator samples built using the operator-sdk, see the samples in operator-sdk/testdata/.

FAQ

For common Operator SDK related questions, see the FAQ.

Contributing

See CONTRIBUTING for details on submitting patches and the contribution workflow.

See the proposal docs and issues for ongoing or planned work.

Reporting bugs

See reporting bugs for details about reporting any issues.

License

Operator SDK is under Apache 2.0 license. See the LICENSE file for details.


Project Layout

A description of the layout of projects built with Operator SDK

Cheat Sheet

Operator-SDK Cheat Sheet commands and operations