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context-recommended-plugins.md

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Context Recommended Plugin Installation

Abstract

The Tanzu CLI is an amalgamation of all the Tanzu infrastructure elements under one unified core CLI experience. The core CLI supports a plugin model where the developers of different Tanzu services (bundled or SaaS) can distribute plugins that target the functionalities of the services they own. When users switch between different services via the CLI context, we want to surface only the relevant plugins for the given context for a crisp user experience.

When a user is working with multiple instances of a product, we want to automatically select the right set of plugins and plugin versions for use based on the active context the user is connected to.

The goals of the Context-Recommended Plugin Installation feature are:

As a plugin developer, I want to,

  • Recommend relevant plugins and their versions that might be needed by the user once the user creates a context.

As a user, I want to,

  • Install the recommended version of all plugins for the active context during context create
  • Install the recommended version of any missing plugin for the active context via a tanzu plugin sync command
  • Upgrade all installed plugins to newer versions via a tanzu plugin sync command, if the installed versions are not supported anymore
  • Avoid re-downloading a plugin version if it was already installed previously (e.g., if the same version of the package plugin is provided by two management clusters, do not re-download that plugin)

Plugin Discovery and Distribution

Discovery is the interface to fetch the list of available plugins, their supported versions, and how to download them. The Tanzu CLI has a plugin discovery source configured by default which returns the list of all available plugins. In the future, this can be made configurable to allow more than one discovery source.

Distribution is the interface to download a plugin binary for a given OS and architecture combination. A discovery source provides details about the distribution regarding where to fetch the plugin binary.

Plugin availability is solely dependent on the configured discovery sources in the tanzu configuration file. Each discovery source points to a plugin repository which can contain one or more plugins.

Context-Recommended Plugins

As mentioned above in the abstract section, there might be a scenario when a user is working with multiple contexts at a time and wants to automatically select the right set of plugins and plugin versions based on the currently active context. The context-recommended plugin implementation is useful in this scenario.

When the CLI user creates a new context for the Tanzu CLI using the tanzu context create command, the CLI adds a context in the tanzu configuration file and marks the newly created context as an active context for the specified target.

Now, this newly created context can also recommend the list of plugins and their versions that are needed to be installed on the user's machine to interact with the created context. The Tanzu CLI automatically detects the list of recommended plugins and their versions and installs them as part of the tanzu context create or tanzu context use commands. Below is the workflow of context-recommended plugin installation:

  • The user runs the tanzu context create or tanzu context use commands to create a new context or switch active context
  • The Tanzu CLI gets the list of recommended plugins and their version from the created context
  • The Tanzu CLI finds the plugins and their metadata in the available list of plugins generated from the configured discovery sources
  • The Tanzu CLI fetches the plugin binary for these plugins from the specified location and installs the plugin

If the user switches the context to a different context using the tanzu context use command, the CLI will automatically install/update the recommended plugins based on the new context.

Note: Users should understand that these plugins (installed based on a recommendation from a context) are installed as normal plugins and will not be automatically deleted when a user deletes the context or switches the context to a different context. Commands associated with those plugins will remain available to be used but will likely throw an error if those plugins do not work with the active context.

Plugin Recommendations from a Context

This section provides more details on how a context can provide recommended plugins to automatically install when a user creates or activates the context.

When the context is of type Kubernetes

When the context is of type kubernetes, the Tanzu CLI uses a kubernetes discovery to fetch the list of recommended plugins and their versions. Using the kubernetes discovery implementation the Tanzu CLI queries the CLIPlugin resources available on the kubernetes cluster.

For example, if the user is expected to use the plugins cluster:v1.0.0 and feature:v1.2.0 when talking to the kubernetes cluster test-cluster then the cluster should have the below CLIPlugin resources defined:

apiVersion: cli.tanzu.vmware.com/v1alpha1
kind: CLIPlugin
metadata:
  name: cluster
spec:
  recommendedVersion: v1.0.0
  description: Kubernetes cluster operations
apiVersion: cli.tanzu.vmware.com/v1alpha1
kind: CLIPlugin
metadata:
  name: feature
spec:
  recommendedVersion: v1.2.0
  description: Feature plugin operations

Note: Starting with v1.1.0 version of Tanzu CLI, it supports providing shortened version (vMAJOR or vMAJOR.MINOR) as part of the recommendedVersion. Using shortened version as above, will install the latest available minor.patch of vMAJOR and latest patch version of vMAJOR.MINOR respectively.

For Tanzu CLI to read these CLIPlugin resources available on the kubernetes cluster get and list RBAC permission needs to be given to all the users. To do that please configure below RBAC rules on your kubernetes cluster.

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: read-cli-plugins
rules:
- apiGroups: ["cli.tanzu.vmware.com"]
  resources: ["cliplugins"]
  verbs: ["get", "list"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
 name: read-cli-plugins-rolebinding
subjects:
- kind: Group
  name: system:authenticated
  apiGroup: rbac.authorization.k8s.io
roleRef:
  kind: ClusterRole
  name: read-cli-plugins
  apiGroup: rbac.authorization.k8s.io

When the context is of type Mission-Control

When the context is of type mission control, the Tanzu CLI uses a REST discovery to fetch the list of recommended plugins and their versions. Using the REST discovery implementation the Tanzu CLI queries the <server-url>/v1alpha1/system/binaries/plugins REST API that should return a list of CLIPlugin information.