Use envsubst to make populating documented aws-hosted-cp easier

Signed-off-by: Kyle Squizzato <[email protected]>

docs/aws/hosted-control-plane.md

@@ -17,63 +17,51 @@ The networking resources in AWS which are needed for a managed cluster can be
 reused with a management cluster.
 
 If you deployed your AWS Kubernetes cluster using Cluster API Provider AWS (CAPA)
-you can obtain all the necessary data with the commands below:
+you can obtain all the necessary data with the commands in [HMC Deployment manifest](#hmc-deployment-manifest).
 
-**VPC ID**
-
-```bash
-    kubectl get awscluster <cluster name> -o go-template='{{.spec.network.vpc.id}}'
-```
+If you want to use different VPCs/regions for your management or managed clusters
+you should setup additional connectivity rules like [VPC peering](https://docs.aws.amazon.com/whitepapers/latest/building-scalable-secure-multi-vpc-network-infrastructure/vpc-peering.html).
 
-**Subnet ID**
 
-```bash
-    kubectl get awscluster <cluster name> -o go-template='{{(index .spec.network.subnets 0).resourceID}}'
-```
+## HMC Deployment manifest
 
-**Availability zone**
+Grab the following `Deployment` manifest and save it to a file:
 
-```bash
-    kubectl get awscluster <cluster name> -o go-template='{{(index .spec.network.subnets 0).availabilityZone}}'
+```yaml
+apiVersion: hmc.mirantis.com/v1alpha1
+kind: Deployment
+metadata:
+  name: aws-hosted-cp
+spec:
+  template: aws-hosted-cp
+  config:
+    vpcID: ${VPC_ID}
+    region: ${AWS_REGION}
+    publicIP: true
+    subnets:
+      - id: ${AWS_SUBNET_ID}
+        availabilityZone: ${AWS_AVAILABILITY_ZONE}
+    amiID: ${AWS_AMI_ID}
+    instanceType: t3.medium
+    securityGroupIDs:
+      - ${AWS_SECURITY_GROUP_ID}
 ```
 
-**Security group**
-```bash
-    kubectl get awscluster <cluster name> -o go-template='{{.status.networkStatus.securityGroups.node.id}}'
-```
+If deploying using resources from a prior managed cluster, you can use the
+commands below, or populate the values manually.
 
-**AMI id**
 
-```bash
-    kubectl get awsmachinetemplate <cluster name>-worker-mt -o go-template='{{.spec.template.spec.ami.id}}'
 ```
+export CLUSTER_NAME="aws-hosted"
 
-If you want to use different VPCs/regions for your management or managed clusters
-you should setup additional connectivity rules like [VPC peering](https://docs.aws.amazon.com/whitepapers/latest/building-scalable-secure-multi-vpc-network-infrastructure/vpc-peering.html).
+export VPC_ID=$(kubectl get awscluster $CLUSTER_NAME -o go-template='{{.spec.network.vpc.id}}')
+export AWS_SUBNET_ID=$(kubectl get awscluster $CLUSTER_NAME -o go-template='{{(index .spec.network.subnets 0).resourceID}}')
+export AWS_AVAILABILITY_ZONE=$(kubectl get awscluster $CLUSTER_NAME -o go-template='{{(index .spec.network.subnets 0).availabilityZone}}')
+export AWS_SECURITY_GROUP_ID=$(kubectl get awscluster $CLUSTER_NAME -o go-template='{{.status.networkStatus.securityGroups.node.id}}')
+export AWS_AMI_ID=$(kubectl get awsmachinetemplate $CLUSTER_NAME-worker-mt -o go-template='{{.spec.template.spec.ami.id}}')
 
-
-## HMC Deployment manifest
-
-With all the collected data your `Deployment` manifest will look similar to this:
-
-```yaml
-    apiVersion: hmc.mirantis.com/v1alpha1
-    kind: Deployment
-    metadata:
-      name: aws-hosted-cp
-    spec:
-      template: aws-hosted-cp
-      config:
-        vpcID: vpc-0a000000000000000
-        region: us-west-1
-        publicIP: true
-        subnets:
-          - id: subnet-0aaaaaaaaaaaaaaaa
-            availabilityZone: us-west-1b
-        amiID: ami-0bfffffffffffffff
-        instanceType: t3.medium
-        securityGroupIDs:
-          - sg-0e000000000000000
+envsubst < deployment.yaml > deployment-aws-hosted-cp.yaml
 ```
 
-*Note: in this example we're using us-west-1 region, but you should use the region of your VPC*
+> [!NOTE]
+> In this example we're using the configured `$AWS_REGION`, but you should use the region of your VPC.