Chapter 1. Understanding OpenShift Pipelines
OpenShift Pipelines is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.
For more information about the support scope of Red Hat Technology Preview features, see https://access.redhat.com/support/offerings/techpreview/.
OpenShift Pipelines is a cloud-native, continuous integration and continuous delivery (CI/CD) solution based on Kubernetes resources. It uses Tekton building blocks to automate deployments across multiple platforms by abstracting away the underlying implementation details. Tekton introduces a number of standard Custom Resource Definitions (CRDs) for defining CI/CD pipelines that are portable across Kubernetes distributions.
1.1. Key features
- OpenShift Pipelines is a serverless CI/CD system that runs Pipelines with all the required dependencies in isolated containers.
- OpenShift Pipelines are designed for decentralized teams that work on microservice-based architecture.
- OpenShift Pipelines use standard CI/CD pipeline definitions that are easy to extend and integrate with the existing Kubernetes tools, enabling you to scale on-demand.
- You can use OpenShift Pipelines to build images with Kubernetes tools such as Source-to-Image (S2I), Buildah, Buildpacks, and Kaniko that are portable across any Kubernetes platform.
- You can use the OpenShift Container Platform Developer Console to create Tekton resources, view logs of Pipeline runs, and manage pipelines in your OpenShift Container Platform namespaces.
1.2. OpenShift Pipelines concepts
OpenShift Pipelines provide a set of standard Custom Resource Definitions (CRDs) that act as the building blocks from which you can assemble a CI/CD pipeline for your application.
- Task
- A Task is the smallest configurable unit in a Pipeline. It is essentially a function of inputs and outputs that form the Pipeline build. It can run individually or as a part of a Pipeline. A Pipeline includes one or more Tasks, where each Task consists of one or more steps. Steps are a series of commands that are sequentially executed by the Task.
- Pipeline
- A Pipeline consists of a series of Tasks that are executed to construct complex workflows that automate the build, deployment, and delivery of applications. It is a collection of PipelineResources, parameters, and one or more Tasks. A Pipeline interacts with the outside world by using PipelineResources, which are added to Tasks as inputs and outputs.
- PipelineRun
- A PipelineRun is the running instance of a Pipeline. A PipelineRun initiates a Pipeline and manages the creation of a TaskRun for each Task being executed in the Pipeline.
- TaskRun
- A TaskRun is automatically created by a PipelineRun for each Task in a Pipeline. It is the result of running an instance of a Task in a Pipeline. It can also be manually created if a Task runs outside of a Pipeline.
- PipelineResource
- A PipelineResource is an object that is used as an input and output for Pipeline Tasks. For example, if an input is a Git repository and an output is a container image built from that Git repository, these are both classified as PipelineResources. PipelineResources currently support Git resources, Image resources, Cluster resources, Storage Resources and CloudEvent resources.
- Trigger
- A Trigger captures an external event, such as a Git pull request and processes the event payload to extract key pieces of information. This extracted information is then mapped to a set of predefined parameters, which trigger a series of tasks that may involve creation and deployment of Kubernetes resources. You can use Triggers along with Pipelines to create full-fledged CI/CD systems where the execution is defined entirely through Kubernetes resources.
- Condition
-
A Condition refers to a validation or check, which is executed before a Task is run in your Pipeline. Conditions are like
ifstatements which perform logical tests, with a return value ofTrueorFalse. A Task is executed if all Conditions returnTrue, but if any of the Conditions fail, the Task and all subsequent Tasks are skipped. You can use Conditions in your Pipeline to create complex workflows covering multiple scenarios.
Additional resources
- For information on installing Pipelines, see Installing OpenShift Pipelines.
- For more details on creating custom CI/CD solutions, see Creating applications with CI/CD Pipelines.
