Technical Requirements

Additional requirements specific to the implementation for all Community, and Validated patterns

Must

1. Patterns MUST include one or more Git repositories, in a publicly accessible location, containing configuration elements that can be consumed by the OpenShift GitOps operator (ArgoCD) without supplying custom ArgoCD images.

2. Patterns MUST be useful without all content stored in private git repos

3. Patterns MUST include a list of names and versions of all the products and projects being consumed by the pattern

4. Patterns MUST be useful without any sample applications that are private or lack public sources.

   Patterns must not become useless due to bit rot or opaque incompatibilities in closed source “applications”.

5. Patterns MUST NOT store sensitive data elements, including but not limited to passwords, in Git

6. Patterns MUST be possible to deploy on any IPI-based OpenShift cluster (BYO)

   We distinguish between the provisioning and configuration requirements of the initial cluster (“Patterns”), and of clusters/machines managed by the initial cluster (see “Managed clusters”)

7. Patterns MUST use a standardized clustergroup Helm chart, as the initial OpenShift GitOps application that describes all namespaces, subscriptions, and any other GitOps applications which contain the configuration elements that make up the solution.

8. Managed clusters MUST operate on the premise of “eventual consistency” (automatic retries, and an expectation of idempotence), which is one of the essential benefits of the GitOps model.

9. Imperative elements MUST be implemented as idempotent code stored in Git

Should

1. Patterns SHOULD include sample application(s) to demonstrate the business problem(s) addressed by the pattern.

2. Patterns SHOULD try to indicate which parts are foundational as opposed to being for demonstration purposes.

3. Patterns SHOULD use the VP operator to deploy patterns. However anything that creates the OpenShift GitOps subscription and initial clustergroup application could be acceptable.

4. Patterns SHOULD embody the “open hybrid cloud model” unless there is a compelling reason to limit the availability of functionality to a specific platform or topology.

5. Patterns SHOULD use industry standards and Red Hat products for all required tooling

   Patterns prefer current best practices at the time of pattern development. Solutions that do not conform to best practices should expect to justify non-conformance and/or expend engineering effort to conform.

6. Patterns SHOULD NOT make use of upstream/community operators and images except, depending on the market segment, where critical to the overall solution.

   Such operators are forbidden to be deployed into an increasing number of customer environments, which limits reuse. Alternatives include productizing the operator, and building it in-cluster from trusted sources as part of the pattern.

7. Patterns SHOULD be decomposed into modules that perform a specific function, so that they can be reused in other patterns.

   For example, Bucket Notification is a capability in the Medical Diagnosis pattern that could be used for other solutions.

8. Patterns SHOULD use Ansible Automation Platform to drive the declarative provisioning and management of managed hosts (e.g. RHEL). See also “Imperative elements”.

9. Patterns SHOULD use RHACM to manage policy and compliance on any managed clusters.

10. Patterns SHOULD use RHACM and a standardized acm chart to deploy and configure OpenShift GitOps to managed clusters.

11. Managed clusters SHOULD be loosely coupled to their hub, and use OpenShift GitOps to consume applications and configuration directly from Git as opposed to having hard dependencies on a centralized cluster.

12. Managed clusters SHOULD use the “pull” deployment model for obtaining their configuration.

13. Imperative elements SHOULD be implemented as Ansible playbooks

14. Imperative elements SHOULD be driven declaratively – by which we mean that the playbooks should be triggered by Jobs and/or CronJobs stored in Git and delivered by OpenShift GitOps.

Can

1. Patterns CAN include additional configuration and/or demo elements located in one or more additional private git repos.
2. Patterns CAN include automation that deploys a known set of clusters and/or machines in a specific topology
3. Patterns CAN limit functionality/testing claims to specific platforms, topologies, and cluster/node sizes
4. Patterns CAN consume operators from established partners (e.g. Hashicorp Vault, and Seldon)
5. Patterns CAN include managed clusters
6. Patterns CAN include details or automation for provisioning managed clusters, or rely on the admin to pre-provision them out-of-band.
7. Patterns CAN also choose to model multi-cluster solutions as an uncoordinated collection of “initial hub clusters”
8. Imperative elements CAN interact with cluster state and/or external influences