With a focus on having minimal human actions required, both in its deployment and operation, MetalK8s also intends to ease deployment and operation of complex applications, named Solutions, on its cluster.
This document defines what a Solution refers to, the responsibilities of each party in this integration, and will link to relevant documentation pages for detailed information.
What is a Solution?¶
We use the term Solution to describe a packaged Kubernetes application, archived as an ISO disk image, containing:
A set of OCI images to inject in MetalK8s image registry
An Operator to deploy on the cluster
Optionally, a UI for managing and monitoring the application
For more details, see the following documentation pages:
(TODO) Solution UI guidelines
Once a Solution is imported in MetalK8s, a user can deploy one or more versions
of the Solution Operator, using either the MetalK8s Solution CLI
./solutions.sh) or the MetalK8s UI Environment page, into separate
Environments (namespaces). Using the Operator-defined
CustomResource(s), the user can then effectively deploy the application
packaged in the Solution.
How is a Solution declared in MetalK8s?¶
MetalK8s uses a
BootstrapConfiguration object, stored in
/etc/metalk8s/bootstrap.yaml, to define how the cluster should be
configured from the bootstrap node, and what versions of MetalK8s are available
to the cluster.
In the same vein, we use a
SolutionsConfiguration object, stored in
/etc/metalk8s/solutions.yaml, to declare which Solutions are available to
the cluster, from the bootstrap node.
Here is how it looks like:
apiVersion: metalk8s.scality.com/v1alpha1 kind: SolutionsConfiguration archives: - /solutions/storage_1.0.0.iso - /solutions/storage_latest.iso - /other_solutions/computing.iso active: storage: 1.0.0
There is no explicit information about what an archive contains. Instead, we want the archive itself to contain such information (more details in Solution archive guidelines), and to discover it at import time.
Note that Solutions are imported based on this file contents, i.e. the images they contain are made available in the registry and the Operator is deployed, however deploying subsequent application(s) is left to the user, through manual operations or the Solution UI.
Removing an archive path from the
Solutions list effectively
removes its related resources (CRDs, images) from a MetalK8s cluster.
Responsibilities of each party¶
This section intends to define the boundaries between MetalK8s and the Solutions to integrate with, in terms of “who is doing what?”.
This is still a work in progress.
Handle reading and mounting of the Solution ISO archive
Provide tooling to deploy/upgrade a Solution’s CRDs and Operator
Provide tooling to verify signatures in a Solution ISO
Expose management of Solutions in its own UI
Comply with the standard archive structure defined by MetalK8s
If providing a UI, expose management of its Operator instances
Handle monitoring of its own services (both Operator and application)
Use MetalK8s monitoring services (Prometheus and Grafana)
Solutions can leverage the Prometheus Operator CRs for setting up the monitoring of their components. For more information, see Monitoring and Solution Operator guidelines.
We include a detailed interaction sequence diagram for describing how MetalK8s will handle user input when deploying / upgrading Solutions.
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