Chapter 4. GitOps
4.1. About Red Hat OpenShift GitOps
Red Hat OpenShift GitOps is an Operator that uses Argo CD as the declarative GitOps engine. It enables GitOps workflows across multicluster OpenShift and Kubernetes infrastructure. Using Red Hat OpenShift GitOps, administrators can consistently configure and deploy Kubernetes-based infrastructure and applications across clusters and development lifecycles. Red Hat OpenShift GitOps is based on the open source project Argo CD and provides a similar set of features to what the upstream offers, with additional automation, integration into Red Hat {OCP} and the benefits of Red Hat’s enterprise support, quality assurance and focus on enterprise security.
Because Red Hat OpenShift GitOps releases on a different cadence from {OCP}, the Red Hat OpenShift GitOps documentation is now available as separate documentation sets for each minor version of the product.
The Red Hat OpenShift GitOps documentation is available at https://docs.openshift.com/gitops/.
Documentation for specific versions is available using the version selector dropdown, or directly by adding the version to the URL, for example, https://docs.openshift.com/gitops/1.8.
In addition, the Red Hat OpenShift GitOps documentation is also available on the Red Hat Portal at https://access.redhat.com/documentation/en-us/red_hat_openshift_gitops/.
For additional information about the Red Hat OpenShift GitOps life cycle and supported platforms, refer to the Platform Life Cycle Policy.
Red Hat OpenShift GitOps ensures consistency in applications when you deploy them to different clusters in different environments, such as: development, staging, and production. Red Hat OpenShift GitOps organizes the deployment process around the configuration repositories and makes them the central element. It always has at least two repositories:
- Application repository with the source code
- Environment configuration repository that defines the desired state of the application
These repositories contain a declarative description of the infrastructure you need in your specified environment. They also contain an automated process to make your environment match the described state.
Red Hat OpenShift GitOps uses Argo CD to maintain cluster resources. Argo CD is an open-source declarative tool for the continuous integration and continuous deployment (CI/CD) of applications. Red Hat OpenShift GitOps implements Argo CD as a controller so that it continuously monitors application definitions and configurations defined in a Git repository. Then, Argo CD compares the specified state of these configurations with their live state on the cluster.
Argo CD reports any configurations that deviate from their specified state. These reports allow administrators to automatically or manually resync configurations to the defined state. Therefore, Argo CD enables you to deliver global custom resources, like the resources that are used to configure {OCP} clusters.
4.1.1. Key features
Red Hat OpenShift GitOps helps you automate the following tasks:
- Ensure that the clusters have similar states for configuration, monitoring, and storage
- Apply or revert configuration changes to multiple {OCP} clusters
- Associate templated configuration with different environments
- Promote applications across clusters, from staging to production
