Document update variants

* Fix terraform-google-modules#317

autogen/README.md

@@ -25,6 +25,28 @@ If you are using these features with a private cluster, you will need to either:
 3. Include the external IP of your Terraform deployer in the `master_authorized_networks` configuration. Note that only IP addresses reserved in Google Cloud (such as in other VPCs) can be whitelisted.
 4. Deploy a [bastion host](https://github.com/terraform-google-modules/terraform-google-bastion-host) or [proxy](https://cloud.google.com/solutions/creating-kubernetes-engine-private-clusters-with-net-proxies) in the same VPC as your GKE cluster.
 
+## Private Cluster Update
+
+In [#256] update variants added support for node pools to be created before being destroyed.
+
+Before, if a node pool has to be recreated for any number of reasons, 
+the node pool is deleted then, created. This can be a problem if it is the only node pool in the GKE
+cluster and the new node pool cannot be provisioned. In this scenario, pods could not be scheduled.
+[#256] allows a node pool to be created before it is deleted so that any issues with node pool creation 
+and/or provisioning are discovered before the node pool is removed. This feature is controlled by the 
+variable `node_pools_create_before_destroy`. In order to avoid node pool name collisions, 
+a 4 character alphanumeric is added as a suffix to the name.
+
+The benefit is that you always have some node pools active. 
+We don't actually cordon/drain the traffic beyond what the GKE API itself will do, 
+but we do make sure the new node pool is created before the old one is destroyed. 
+
+The implications of this are that:
+
+- We append a random ID on the node pool names (since you can't have two simultaneously active node pools)
+- For a brief period, you'll have 2x as many resources/node pools
+- You will indeed need sufficient IP space (and compute capacity) to create both node pools
+
 {% endif %}
 
 ## Compatibility

modules/beta-private-cluster-update-variant/README.md

@@ -23,6 +23,28 @@ If you are using these features with a private cluster, you will need to either:
 3. Include the external IP of your Terraform deployer in the `master_authorized_networks` configuration. Note that only IP addresses reserved in Google Cloud (such as in other VPCs) can be whitelisted.
 4. Deploy a [bastion host](https://github.com/terraform-google-modules/terraform-google-bastion-host) or [proxy](https://cloud.google.com/solutions/creating-kubernetes-engine-private-clusters-with-net-proxies) in the same VPC as your GKE cluster.
 
+## Private Cluster Update
+
+In [#256] update variants added support for node pools to be created before being destroyed.
+
+Before, if a node pool has to be recreated for any number of reasons, 
+the node pool is deleted then, created. This can be a problem if it is the only node pool in the GKE
+cluster and the new node pool cannot be provisioned. In this scenario, pods could not be scheduled.
+[#256] allows a node pool to be created before it is deleted so that any issues with node pool creation 
+and/or provisioning are discovered before the node pool is removed. This feature is controlled by the 
+variable `node_pools_create_before_destroy`. In order to avoid node pool name collisions, 
+a 4 character alphanumeric is added as a suffix to the name.
+
+The benefit is that you always have some node pools active. 
+We don't actually cordon/drain the traffic beyond what the GKE API itself will do, 
+but we do make sure the new node pool is created before the old one is destroyed. 
+
+The implications of this are that:
+
+- We append a random ID on the node pool names (since you can't have two simultaneously active node pools)
+- For a brief period, you'll have 2x as many resources/node pools
+- You will indeed need sufficient IP space (and compute capacity) to create both node pools
+
 
 ## Compatibility
 

modules/beta-private-cluster/README.md

@@ -23,6 +23,28 @@ If you are using these features with a private cluster, you will need to either:
 3. Include the external IP of your Terraform deployer in the `master_authorized_networks` configuration. Note that only IP addresses reserved in Google Cloud (such as in other VPCs) can be whitelisted.
 4. Deploy a [bastion host](https://github.com/terraform-google-modules/terraform-google-bastion-host) or [proxy](https://cloud.google.com/solutions/creating-kubernetes-engine-private-clusters-with-net-proxies) in the same VPC as your GKE cluster.
 
+## Private Cluster Update
+
+In [#256] update variants added support for node pools to be created before being destroyed.
+
+Before, if a node pool has to be recreated for any number of reasons, 
+the node pool is deleted then, created. This can be a problem if it is the only node pool in the GKE
+cluster and the new node pool cannot be provisioned. In this scenario, pods could not be scheduled.
+[#256] allows a node pool to be created before it is deleted so that any issues with node pool creation 
+and/or provisioning are discovered before the node pool is removed. This feature is controlled by the 
+variable `node_pools_create_before_destroy`. In order to avoid node pool name collisions, 
+a 4 character alphanumeric is added as a suffix to the name.
+
+The benefit is that you always have some node pools active. 
+We don't actually cordon/drain the traffic beyond what the GKE API itself will do, 
+but we do make sure the new node pool is created before the old one is destroyed. 
+
+The implications of this are that:
+
+- We append a random ID on the node pool names (since you can't have two simultaneously active node pools)
+- For a brief period, you'll have 2x as many resources/node pools
+- You will indeed need sufficient IP space (and compute capacity) to create both node pools
+
 
 ## Compatibility
 

modules/private-cluster-update-variant/README.md

@@ -23,6 +23,28 @@ If you are using these features with a private cluster, you will need to either:
 3. Include the external IP of your Terraform deployer in the `master_authorized_networks` configuration. Note that only IP addresses reserved in Google Cloud (such as in other VPCs) can be whitelisted.
 4. Deploy a [bastion host](https://github.com/terraform-google-modules/terraform-google-bastion-host) or [proxy](https://cloud.google.com/solutions/creating-kubernetes-engine-private-clusters-with-net-proxies) in the same VPC as your GKE cluster.
 
+## Private Cluster Update
+
+In [#256] update variants added support for node pools to be created before being destroyed.
+
+Before, if a node pool has to be recreated for any number of reasons, 
+the node pool is deleted then, created. This can be a problem if it is the only node pool in the GKE
+cluster and the new node pool cannot be provisioned. In this scenario, pods could not be scheduled.
+[#256] allows a node pool to be created before it is deleted so that any issues with node pool creation 
+and/or provisioning are discovered before the node pool is removed. This feature is controlled by the 
+variable `node_pools_create_before_destroy`. In order to avoid node pool name collisions, 
+a 4 character alphanumeric is added as a suffix to the name.
+
+The benefit is that you always have some node pools active. 
+We don't actually cordon/drain the traffic beyond what the GKE API itself will do, 
+but we do make sure the new node pool is created before the old one is destroyed. 
+
+The implications of this are that:
+
+- We append a random ID on the node pool names (since you can't have two simultaneously active node pools)
+- For a brief period, you'll have 2x as many resources/node pools
+- You will indeed need sufficient IP space (and compute capacity) to create both node pools
+
 
 ## Compatibility
 

modules/private-cluster/README.md

@@ -23,6 +23,28 @@ If you are using these features with a private cluster, you will need to either:
 3. Include the external IP of your Terraform deployer in the `master_authorized_networks` configuration. Note that only IP addresses reserved in Google Cloud (such as in other VPCs) can be whitelisted.
 4. Deploy a [bastion host](https://github.com/terraform-google-modules/terraform-google-bastion-host) or [proxy](https://cloud.google.com/solutions/creating-kubernetes-engine-private-clusters-with-net-proxies) in the same VPC as your GKE cluster.
 
+## Private Cluster Update
+
+In [#256] update variants added support for node pools to be created before being destroyed.
+
+Before, if a node pool has to be recreated for any number of reasons, 
+the node pool is deleted then, created. This can be a problem if it is the only node pool in the GKE
+cluster and the new node pool cannot be provisioned. In this scenario, pods could not be scheduled.
+[#256] allows a node pool to be created before it is deleted so that any issues with node pool creation 
+and/or provisioning are discovered before the node pool is removed. This feature is controlled by the 
+variable `node_pools_create_before_destroy`. In order to avoid node pool name collisions, 
+a 4 character alphanumeric is added as a suffix to the name.
+
+The benefit is that you always have some node pools active. 
+We don't actually cordon/drain the traffic beyond what the GKE API itself will do, 
+but we do make sure the new node pool is created before the old one is destroyed. 
+
+The implications of this are that:
+
+- We append a random ID on the node pool names (since you can't have two simultaneously active node pools)
+- For a brief period, you'll have 2x as many resources/node pools
+- You will indeed need sufficient IP space (and compute capacity) to create both node pools
+
 
 ## Compatibility