Solution Operator guidelines¶
An Operator is a method of packaging, deploying and managing a Kubernetes application. A Kubernetes application is an application that is both deployed on Kubernetes and managed using the Kubernetes APIs and
MetalK8s Solutions are a concept mostly centered around the Operator pattern. While there is no explicit requirements except the ones described below (see Requirements), we recommend using the Operator SDK as it will embed best practices from the Kubernetes community.
All Operator-related files except for the container images (see
OCI images) should be stored under
/operator in the ISO
archive. Those files should be organized as follows:
operator └── deploy ├── crds │ └── some_crd.yaml └── role.yaml
Most of these files are generated when using the Operator SDK.
MetalK8s does not handle the monitoring of a Solution application, which means:
the user, manually or through the Solution UI, should create
ServiceMonitorobjects for each Operator instance
Operators should create
ServiceMonitorobjects for each deployed component they own
The Prometheus Operator deployed by MetalK8s has cluster-scoped permissions,
and is able to read the aforementioned
to set up monitoring of your application services.
Solution Operator must implement a
--config option which will be used
by MetalK8s to provide various useful information needed by the Operator, such
as the endpoints for the container images.
The given configuration looks like:
apiVersion: solutions.metalk8s.scality.com/v1alpha1 kind: OperatorConfig repositories: <solution-version-x>: - endpoint: metalk8s-registry/<solution-name>-<solution-version-x> images: - <image-x>:<tag-x> - <image-y>:<tag-y> <solution-version-y>: - endpoint: metalk8s-registry/<solution-name>-<solution-version-y> images: - <image-x>:<tag-x> - <image-y>:<tag-y>
In example, for an online installation without MetalK8s providing the repository, this configuration could be:
apiVersion: solutions.metalk8s.scality.com/v1alpha1 kind: OperatorConfig repositories: 1.0.0: - endpoint: registry.scality.com/zenko images: - cloudserver:1.0.0 - zenko-quorum:1.0.0 - endpoint: quay.io/coreos images: - prometheus-operator:v0.34.0
This configuration allows the Operator to retrieve dynamically where the container images are stored for each version of a given Solution.
Solution must ship a
role.yaml file located in
directory. This file is a manifest which declares all necessary
ClusterRole objects needed by the Operator.
MetalK8s will take care of deploying these objects, create a
<solution_name>-operator and all needed
RoleBinding to bind these
roles to this account.
ClusterRole kinds are allowed in this file,
the deployment of the Solution fails if any other resource is found.