docs: add the gateway-api to the expose-a-service doc

The Expose a Service doc is meant to be the second step after the
Quickstart doc.  This commit adds the section describing how to install
the Gateway API.

The Kustomize build plan is introduced at this point in a similar way
the Helm build plan was introduced in the quickstart.

.cspell.json

@@ -31,17 +31,20 @@
     "errgroup",
     "fieldmaskpb",
     "flushcache",
+    "gatewayclasses",
     "gendoc",
     "ghaction",
     "gitops",
     "godoc",
     "golangci",
     "goreleaser",
     "grpcreflect",
+    "grpcroutes",
     "grpcurl",
     "holos",
     "holoslogger",
     "httpbin",
+    "httproutes",
     "Infima",
     "isatty",
     "istiod",
@@ -79,6 +82,7 @@
     "Pulumi",
     "putenv",
     "quickstart",
+    "referencegrants",
     "retryable",
     "ropc",
     "SECRETKEY",

api/schema/v1alpha3/definitions.go

@@ -148,3 +148,16 @@ type Platform struct {
 	// and render each listed Component, injecting the Model.
 	Output core.Platform
 }
+
+// Kustomize provides a BuildPlan via the Output field which contains one
+// KustomizeBuild from package core.
+type Kustomize struct {
+	// Name represents the chart name.
+	Name string
+
+	// Kustomization represents the kustomize build plan for holos to render.
+	Kustomization core.KustomizeBuild
+
+	// Output represents the derived BuildPlan for the Holos cli to render.
+	Output core.BuildPlan
+}

doc/md/api/schema/v1alpha3.md

@@ -14,6 +14,7 @@ Package v1alpha3 contains CUE definitions intended as convenience wrappers aroun
 - [type Cluster](<#Cluster>)
 - [type Fleet](<#Fleet>)
 - [type Helm](<#Helm>)
+- [type Kustomize](<#Kustomize>)
 - [type Platform](<#Platform>)
 - [type StandardFleets](<#StandardFleets>)
 
@@ -131,6 +132,24 @@ type Helm struct {
 }
 ```
 
+<a name="Kustomize"></a>
+## type Kustomize {#Kustomize}
+
+Kustomize provides a BuildPlan via the Output field which contains one KustomizeBuild from package core.
+
+```go
+type Kustomize struct {
+    // Name represents the chart name.
+    Name string
+
+    // Kustomization represents the kustomize build plan for holos to render.
+    Kustomization core.KustomizeBuild
+
+    // Output represents the derived BuildPlan for the Holos cli to render.
+    Output core.BuildPlan
+}
+```
+
 <a name="Platform"></a>
 ## type Platform {#Platform}
 

doc/md/guides/expose-a-service.mdx

@@ -13,24 +13,16 @@ import Admonition from '@theme/Admonition';
 In this guide, you'll learn how to expose a service with Holos using the Gateway
 API.
 
-:::warning TODO
-Complete this section once the steps are complete.
-:::
-
 The [Concepts](/docs/concepts) page defines capitalized terms such as Platform
 and Component.
 
 ## What you'll need {#requirements}
 
-:::warning TODO
-Complete this section once the steps are complete.
-:::
-
 You'll need the following tools installed to complete this guide.
 
 1. [holos](/docs/install) - to build the Platform.
-2. [helm](https://helm.sh/docs/intro/install/) - to render Holos Components that
-wrap upstream Helm charts.
+2. [helm](https://helm.sh/docs/intro/install/) - to render Helm Components.
+3. [kubectl](https://kubernetes.io/docs/tasks/tools/) - to render Kustomize Components.
 
 Optionally, if you'd like to apply the rendered manifests to a real Cluster,
 first complete the [localhost Guide](../local-cluster).
@@ -60,11 +52,22 @@ repository unless stated otherwise.
 
 ## Generate the Platform {#Generate-Platform}
 
-Start by generating a platform used as the basis for our guides.
+Start by generating a platform with one workload Cluster.  The `guide` Platform
+is intended as a starting point for all of our guides.
 
+<Tabs groupId="generate-platform">
+  <TabItem value="command" label="Command">
 ```bash
 holos generate platform guide
+holos generate component workload-cluster
 ```
+  </TabItem>
+  <TabItem value="output" label="Output">
+```txt
+generated component
+```
+  </TabItem>
+</Tabs>
 
 Commit the generated platform config to the repository.
 
@@ -84,12 +87,88 @@ Commit the generated platform config to the repository.
   </TabItem>
 </Tabs>
 
-## Manage httpbin {#manage-httpbin}
+## Gateway API
+
+The Gateway API is an official Kubernetes project focused on L4 and L7 routing .
+You'll use the custom resources defined by the Gateway API to expose the httpbin
+service outside of the cluster.  The Kubernetes Gateway API does not come
+installed by default on most Kubernetes clusters, so we need to manage the
+custom resource definitions (CRDs).
+
+Run the following command to generate a Component to manage the Gateway API.
+
+<Tabs groupId="gen-gateway-api">
+  <TabItem value="command" label="Command">
+```bash
+holos generate component gateway-api
+```
+  </TabItem>
+  <TabItem value="output" label="Output">
+```txt
+generated component
+```
+  </TabItem>
+</Tabs>
+
+The command generates two main configuration files, one at the leaf, and another
+at the root of the tree.  At the leaf, the config produces a Kustomize build
+plan for Holos to render.  At the root, the config adds the Component to all
+Clusters in the Platform.
+
+<Tabs groupId="gateway-api-files">
+  <TabItem value="components/gateway-api/gateway-api.cue" label="Leaf">
+    `components/gateway-api/gateway-api.cue`
+```cue showLineNumbers
+package holos
+
+// Produce a kubectl kustomize build plan.
+(#Kustomize & {Name: "gateway-api"}).Output
+```
+  </TabItem>
+  <TabItem value="gateway-api.gen.cue" label="Root">
+    `gateway-api.gen.cue`
+```cue showLineNumbers
+package holos
+
+// Manage on every Cluster in the Platform
+for Fleet in #Fleets {
+	for Cluster in Fleet.clusters {
+		#Platform: Components: "\(Cluster.name)/gateway-api": {
+			path:    "components/gateway-api"
+			cluster: Cluster.name
+		}
+	}
+}
+```
+  </TabItem>
+</Tabs>
+
+:::tip
+This example is equivalent to running `kubectl kustomize
+./components/gateway-api` and saving the output to a file.  Holos simplifies
+this task and makes it consistent with Helm and other tools.
+:::
+
+Notice the Component also includes a `kustomization.yaml` file at the leaf.
+This is an unmodified upstream copy of the standard way to install the Gateway
+API.
+
+<Tabs groupId="gateway-kustomization-yaml">
+  <TabItem value="kustomization.yaml" label="kustomization.yaml">
+  `components/gateway-api/kustomization.yaml`
+```yaml showLineNumbers
+resources:
+- standard/gateway.networking.k8s.io_gatewayclasses.yaml
+- standard/gateway.networking.k8s.io_gateways.yaml
+- standard/gateway.networking.k8s.io_grpcroutes.yaml
+- standard/gateway.networking.k8s.io_httproutes.yaml
+- standard/gateway.networking.k8s.io_referencegrants.yaml
+```
+  </TabItem>
+</Tabs>
+
+## Namespaces
 
-The platform you generated is currently empty. Run the following command to
-generate a Holos Component for the
-[httpbin](https://github.com/mccutchen/go-httpbin) service.
+## Istio
 
-httpbin is a simple backend service useful for end-to-end testing.  In this
-guide, we use httpbin as a example of a service your organization develops and
-deploy onto your Platform.
+## httpbin

internal/generate/components/v1alpha3/gateway-api/components/gateway-api/gateway-api.cue

@@ -0,0 +1,4 @@
+package holos
+
+// Produce a kubectl kustomize build plan.
+(#Kustomize & {Name: "gateway-api"}).Output

internal/generate/components/v1alpha3/gateway-api/components/gateway-api/kustomization.yaml

@@ -0,0 +1,6 @@
+resources:
+- standard/gateway.networking.k8s.io_gatewayclasses.yaml
+- standard/gateway.networking.k8s.io_gateways.yaml
+- standard/gateway.networking.k8s.io_grpcroutes.yaml
+- standard/gateway.networking.k8s.io_httproutes.yaml
+- standard/gateway.networking.k8s.io_referencegrants.yaml