[TEP-0115] Support Artifact Hub in Hub Resolver

Part of [issues/667].
This commit adds support to resolve catalog resource from the [Artifact Hub] while keeping current functionality of fetching resources from Tekton Hub.

- Change 1:

The commit adds a new field `type` to the hub resolver indicating the type of the Hub to pull the resource from. The value can be set to `tekton` or `artifact`. By default, the resolver fetches resources from `https://artifacthub.io/` when setting `type: artifact`, and fetches resources from user's private instance of Tekton Hub when setting `type: tekton`.

- Change 2:

Prior to this change, the hub resolver only supports pulling resources from the Tekton Hub. This commit updates the default hub type to `artifact` since the [Artifact Hub][Artifact Hub] will be the main entrypoint for Tekton Catalogs in the future.

- Change 3:

Prior to this change, the default Tekton Hub URL is: `https://api.hub.tekton.dev`. This commit removes the default value of the Tekton Hub URL and enforces users to configure their own instance of Tekton Hub since the public instance `https://api.hub.tekton.dev` will be deprecated after the migration to Artifact Hub is done.

/kind feature

[Artifact Hub]: https://artifacthub.io/
[issues/667]: tektoncd/hub#667

cmd/resolvers/main.go

@@ -33,21 +33,26 @@ import (
 
 func main() {
 	ctx := filteredinformerfactory.WithSelectors(signals.NewContext(), v1alpha1.ManagedByLabelKey)
-
-	apiURL := os.Getenv("HUB_API")
-	hubURL := hub.DefaultHubURL
-	if apiURL == "" {
-		hubURL = hub.DefaultHubURL
-	} else {
-		if !strings.HasSuffix(apiURL, "/") {
-			apiURL += "/"
-		}
-		hubURL = apiURL + hub.YamlEndpoint
-	}
+	tektonHubURL := buildHubURL(os.Getenv("TEKTON_HUB_API"), "", hub.TektonHubYamlEndpoint)
+	artifactHubURL := buildHubURL(os.Getenv("ARTIFACT_HUB_API"), hub.DefaultArtifactHubURL, hub.ArtifactHubYamlEndpoint)
 
 	sharedmain.MainWithContext(ctx, "controller",
 		framework.NewController(ctx, &git.Resolver{}),
-		framework.NewController(ctx, &hub.Resolver{HubURL: hubURL}),
+		framework.NewController(ctx, &hub.Resolver{TektonHubURL: tektonHubURL, ArtifactHubURL: artifactHubURL}),
 		framework.NewController(ctx, &bundle.Resolver{}),
 		framework.NewController(ctx, &cluster.Resolver{}))
 }
+
+func buildHubURL(configAPI, defaultURL, yamlEndpoint string) string {
+	var hubURL string
+	if configAPI == "" {
+		hubURL = defaultURL
+	} else {
+		if !strings.HasSuffix(configAPI, "/") {
+			configAPI += "/"
+		}
+		hubURL = configAPI + yamlEndpoint
+	}
+
+	return hubURL
+}

config/resolvers/hubresolver-config.yaml

@@ -22,7 +22,13 @@ metadata:
     app.kubernetes.io/instance: default
     app.kubernetes.io/part-of: tekton-pipelines
 data:
-  # the default catalog from where to pull the resource.
-  default-catalog: "Tekton"
-  # The default layer kind in the hub image.
+  # the default Tekton Hub catalog from where to pull the resource.
+  default-tekton-hub-catalog: "Tekton"
+  # the default Artifact Hub Task catalog from where to pull the resource.
+  default-artifact-hub-task-catalog: "tekton-catalog-tasks"
+  # the default Artifact Hub Pipeline catalog from where to pull the resource.
+  default-artifact-hub-pipeline-catalog: "tekton-catalog-pipelines"
+  # the default layer kind in the hub image.
   default-kind: "task"
+  # the default hub source to pull the resource from.
+  default-type: "artifact"

config/resolvers/resolvers-deployment.yaml

@@ -93,8 +93,8 @@ spec:
         - name: METRICS_DOMAIN
           value: tekton.dev/resolution
         # Override this env var to set a private hub api endpoint
-        - name: HUB_API
-          value: "https://api.hub.tekton.dev/"
+        - name: ARTIFACT_HUB_API
+          value: "https://artifacthub.io/"
         securityContext:
           allowPrivilegeEscalation: false
           readOnlyRootFilesystem: true

docs/hub-resolver.md

@@ -6,10 +6,13 @@ Use resolver type `hub`.
 
 | Param Name       | Description                                                                   | Example Value                                              |
 |------------------|-------------------------------------------------------------------------------|------------------------------------------------------------|
-| `catalog`        | The catalog from where to pull the resource (Optional)                        | Default:  `Tekton`                                         |
+| `catalog`        | The catalog from where to pull the resource (Optional)                        | Default:  `tekton-catalog-tasks` (for `Task` kind);  `tekton-catalog-pipelines` (for `Pipeline` kind)                                        |
+| `type`           | The type of Hub from where to pull the resource (Optional). Either `artifact` or `tekton` | Default:  `artifact`                                         |
 | `kind`           | Either `task` or `pipeline`                                                   | `task`                                                     |
 | `name`           | The name of the task or pipeline to fetch from the hub                        | `golang-build`                                             |
-| `version`        | Version of task or pipeline to pull in from hub. Wrap the number in quotes!   | `"0.5"`                                                    |
+| `version`        | Version of task or pipeline to pull in from hub. Wrap the number in quotes!   | `"0.5.0"`                                                    |
+
+The Catalogs in the Artifact Hub follows the semVer (i.e.` <major-version>.<minor-version>.0`) and the Catalogs in the Tekton Hub follows the simplified semVer (i.e. `<major-version>.<minor-version>`). Both full and simplified semantic versioning will be accepted by the `version` parameter. The Hub Resolver will map the version to the format expected by the target Hub `type`.
 
 ## Requirements
 
@@ -26,25 +29,42 @@ for the name, namespace and defaults that the resolver ships with.
 
 ### Options
 
-| Option Name       | Description                                          | Example Values     |
-|-------------------|------------------------------------------------------|--------------------|
-| `default-catalog` | The default catalog from where to pull the resource. | `tekton`           |
-| `default-kind`    | The default object kind for references.              | `task`, `pipeline` |
+| Option Name       | Description                                          | Example Values         |
+|-------------------|------------------------------------------------------|------------------------|
+| `default-catalog` | The default catalog from where to pull the resource. | `tekton-catalog-tasks` |
+| `default-kind`    | The default object kind for references.              | `task`, `pipeline`     |
+| `default-type`    | The default hub from where to pull the resource.     | `artifact`, `tekton`   |
 
 
 ### Configuring the Hub API endpoint
 
-By default this resolver will hit the public hub api at https://hub.tekton.dev/
+The Hub Resolver supports to resolve resources from the [Artifact Hub](https://artifacthub.io/) and the [Tekton Hub](https://hub.tekton.dev/),
+which can be configured by setting the `type` field of the resolver. 
+
+*(Please note that the [Tekton Hub](https://hub.tekton.dev/) will be deprecated after [migration to the Artifact Hub](https://github.com/tektoncd/hub/issues/667) is done.)*
+
+When setting the `type` field to `artifact`, the resolver will hit the public hub api at https://artifacthub.io/ by default
 but you can configure your own (for example to use a private hub
-instance) by setting the `HUB_API` environment variable in
+instance) by setting the `ARTIFACT_HUB_API` environment variable in
+[`../config/resolvers/resolvers-deployment.yaml`](../config/resolvers/resolvers-deployment.yaml). Example:
+
+```yaml
+env
+- name: ARTIFACT_HUB_API
+  value: "https://artifacthub.io/"
+```
+
+When setting the `type` field to `tekton`, you **must** configure your own instance of the Tekton Hub by setting the `TEKTON_HUB_API` environment variable in
 [`../config/resolvers/resolvers-deployment.yaml`](../config/resolvers/resolvers-deployment.yaml). Example:
 
 ```yaml
 env
-- name: HUB_API
-  value: "https://api.hub.tekton.dev/"
+- name: TEKTON_HUB_API
+  value: "https://api.private.hub.instance.dev"
 ```
 
+The Tekton Hub deployment guide can be found [here](https://github.com/tektoncd/hub/blob/main/docs/DEPLOYMENT.md).
+
 ## Usage
 
 ### Task Resolution
@@ -59,7 +79,9 @@ spec:
     resolver: hub
     params:
     - name: catalog # optional
-      value: Tekton
+      value: tekton-catalog-tasks
+    - name: type # optional
+      value: artifact 
     - name: kind
       value: task
     - name: name
@@ -80,7 +102,9 @@ spec:
     resolver: hub
     params:
     - name: catalog # optional
-      value: Tekton 
+      value: tekton-catalog-pipelines 
+    - name: type # optional
+      value: artifact
     - name: kind
       value: pipeline
     - name: name

pkg/resolution/resolver/hub/config.go

@@ -16,10 +16,22 @@ limitations under the License.
 
 package hub
 
-// ConfigCatalog is the configuration field name for controlling
-// the catalog to fetch the remote resource from.
-const ConfigCatalog = "default-catalog"
+// ConfigTektonHubCatalog is the configuration field name for controlling
+// the Tekton Hub catalog to fetch the remote resource from.
+const ConfigTektonHubCatalog = "default-tekton-hub-catalog"
+
+// ConfigArtifactHubTaskCatalog is the configuration field name for controlling
+// the Artifact Hub Task catalog to fetch the remote resource from.
+const ConfigArtifactHubTaskCatalog = "default-artifact-hub-task-catalog"
+
+// ConfigArtifactHubPipelineCatalog is the configuration field name for controlling
+// the Artifact Hub Pipeline catalog to fetch the remote resource from.
+const ConfigArtifactHubPipelineCatalog = "default-artifact-hub-pipeline-catalog"
 
 // ConfigKind is the configuration field name for controlling
 // what the layer name in the hub image is.
 const ConfigKind = "default-kind"
+
+// ConfigType is the configuration field name for controlling
+// the hub type to pull the resource from.
+const ConfigType = "default-type"

pkg/resolution/resolver/hub/params.go

@@ -13,11 +13,14 @@ limitations under the License.
 
 package hub
 
-// DefaultHubURL is de default url for the Tekton hub api
-const DefaultHubURL = "https://api.hub.tekton.dev/v1/resource/%s/%s/%s/%s/yaml"
+// DefaultArtifactHubURL is the default url for the Artifact hub api
+const DefaultArtifactHubURL = "https://artifacthub.io/api/v1/packages/tekton-%s/%s/%s/%s"
 
-// YamlEndpoint is the suffix for a private custom hub instance
-const YamlEndpoint = "v1/resource/%s/%s/%s/%s/yaml"
+// TektonHubYamlEndpoint is the suffix for a private custom Tekton hub instance
+const TektonHubYamlEndpoint = "v1/resource/%s/%s/%s/%s/yaml"
+
+// ArtifactHubYamlEndpoint is the suffix for a private custom Artifact hub instance
+const ArtifactHubYamlEndpoint = "api/v1/packages/tekton-%s/%s/%s/%s"
 
 // ParamName is the parameter defining what the layer name in the bundle
 // image is.
@@ -34,3 +37,6 @@ const ParamVersion = "version"
 // ParamCatalog is the parameter defining what the catalog in the bundle
 // image is.
 const ParamCatalog = "catalog"
+
+// ParamSource is the parameter defining what the hub source to pull the resource from.
+const ParamType = "type"