From d9c7a9e04908a9bc55b4fdca3f79b056ca9fb809 Mon Sep 17 00:00:00 2001
From: Dalton Hubble <dghubble@gmail.com>
Date: Thu, 5 Dec 2019 22:56:42 -0800
Subject: [PATCH] Add/update docs for asset_dir and kubeconfig usage

* Original tutorials favored including the platform (e.g.
google-cloud) in modules (e.g. google-cloud-yavin). Prefer
naming conventions where each module / cluster has a simple
name (e.g. yavin) since the platform is usually redundant
* Retain the example cluster naming themes per platform
---
 CHANGES.md                                    |  8 +++-
 README.md                                     | 11 +++--
 aws/container-linux/kubernetes/variables.tf   |  1 +
 aws/fedora-coreos/kubernetes/variables.tf     |  1 +
 azure/container-linux/kubernetes/variables.tf |  1 +
 .../container-linux/kubernetes/variables.tf   |  1 +
 .../fedora-coreos/kubernetes/variables.tf     |  1 +
 .../container-linux/kubernetes/variables.tf   |  1 +
 docs/addons/ingress.md                        | 10 ++---
 docs/advanced/customization.md                |  6 +--
 docs/advanced/worker-pools.md                 | 24 +++++------
 docs/architecture/concepts.md                 |  2 +-
 docs/cl/aws.md                                | 22 ++++++----
 docs/cl/azure.md                              | 22 ++++++----
 docs/cl/bare-metal.md                         | 40 +++++++++++--------
 docs/cl/digital-ocean.md                      | 26 +++++++-----
 docs/cl/google-cloud.md                       | 26 +++++++-----
 docs/fedora-coreos/aws.md                     | 24 +++++++----
 docs/fedora-coreos/bare-metal.md              | 38 +++++++++++-------
 docs/index.md                                 | 11 +++--
 docs/topics/maintenance.md                    | 14 +++----
 .../container-linux/kubernetes/variables.tf   |  1 +
 22 files changed, 185 insertions(+), 106 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index bb99f125..9ce519d6 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -4,9 +4,15 @@ Notable changes between versions.
 
 ## Latest
 
+* Manage clusters without using a local `asset_dir` ([#595](https://github.com/poseidon/typhoon/pull/595))
+  * Change `asset_dir` to be optional. Default to "" to skip writing assets locally
+  * Keep cluster assets (TLS materials, kubeconfig) only in Terraform state, which supports different [remote backends](https://www.terraform.io/docs/backends/types/remote.html) and optional encryption at rest
+  * Allow `terraform apply` from stateless automation systems
+  * Improve asset unpacking on controllers to remove unused materials
+  * Obtain a kubeconfig from Terraform module outputs
 * Update CoreDNS from v1.6.2 to v1.6.5 ([#588](https://github.com/poseidon/typhoon/pull/588))
   * Add health `lameduck` option to wait before shutdown
-* Add CPU requests to control plane static pods ([#589](https://github.com/poseidon/typhoon/pull/589))
+* Add CPU requests for control plane static pods ([#589](https://github.com/poseidon/typhoon/pull/589))
   * May provide slight edge case benefits and aligns with upstream
 * Replace usage of `template_dir` with `templatefile` function ([#587](https://github.com/poseidon/typhoon/pull/587))
   * Require Terraform version v0.12.6+ (action required)
diff --git a/README.md b/README.md
index 92f310e9..b26355a4 100644
--- a/README.md
+++ b/README.md
@@ -47,7 +47,7 @@ A preview of Typhoon for [Fedora CoreOS](https://getfedora.org/coreos/) is avail
 Define a Kubernetes cluster by using the Terraform module for your chosen platform and operating system. Here's a minimal example:
 
 ```tf
-module "google-cloud-yavin" {
+module "yavin" {
   source = "git::https://github.com/poseidon/typhoon//google-cloud/container-linux/kubernetes?ref=v1.16.3"
 
   # Google Cloud
@@ -58,12 +58,17 @@ module "google-cloud-yavin" {
 
   # configuration
   ssh_authorized_key = "ssh-rsa AAAAB3Nz..."
-  asset_dir          = "/home/user/.secrets/clusters/yavin"
   
   # optional
   worker_count = 2
   worker_preemptible = true
 }
+
+# Obtain cluster kubeconfig
+resource "local_file" "kubeconfig-yavin" {
+  content  = module.yavin.kubeconfig-admin
+  filename = "/home/user/.kube/configs/yavin-config"
+}
 ```
 
 Initialize modules, plan the changes to be made, and apply the changes.
@@ -79,7 +84,7 @@ Apply complete! Resources: 64 added, 0 changed, 0 destroyed.
 In 4-8 minutes (varies by platform), the cluster will be ready. This Google Cloud example creates a `yavin.example.com` DNS record to resolve to a network load balancer across controller nodes.
 
 ```sh
-$ export KUBECONFIG=/home/user/.secrets/clusters/yavin/auth/kubeconfig
+$ export KUBECONFIG=/home/user/.kube/configs/yavin-config
 $ kubectl get nodes
 NAME                                       ROLES    STATUS  AGE  VERSION
 yavin-controller-0.c.example-com.internal  <none>   Ready   6m   v1.16.3
diff --git a/aws/container-linux/kubernetes/variables.tf b/aws/container-linux/kubernetes/variables.tf
index b0189ce2..21c41ff1 100644
--- a/aws/container-linux/kubernetes/variables.tf
+++ b/aws/container-linux/kubernetes/variables.tf
@@ -99,6 +99,7 @@ variable "ssh_authorized_key" {
 variable "asset_dir" {
   type        = string
   description = "Absolute path to a directory where generated assets should be placed (contains secrets)"
+  default     = ""
 }
 
 variable "networking" {
diff --git a/aws/fedora-coreos/kubernetes/variables.tf b/aws/fedora-coreos/kubernetes/variables.tf
index 5d48f19e..890ad288 100644
--- a/aws/fedora-coreos/kubernetes/variables.tf
+++ b/aws/fedora-coreos/kubernetes/variables.tf
@@ -99,6 +99,7 @@ variable "ssh_authorized_key" {
 variable "asset_dir" {
   type        = string
   description = "Absolute path to a directory where generated assets should be placed (contains secrets)"
+  default     = ""
 }
 
 variable "networking" {
diff --git a/azure/container-linux/kubernetes/variables.tf b/azure/container-linux/kubernetes/variables.tf
index 2102454f..c86ab9aa 100644
--- a/azure/container-linux/kubernetes/variables.tf
+++ b/azure/container-linux/kubernetes/variables.tf
@@ -86,6 +86,7 @@ variable "ssh_authorized_key" {
 variable "asset_dir" {
   type        = string
   description = "Absolute path to a directory where generated assets should be placed (contains secrets)"
+  default     = ""
 }
 
 variable "networking" {
diff --git a/bare-metal/container-linux/kubernetes/variables.tf b/bare-metal/container-linux/kubernetes/variables.tf
index 4ebdbf06..80dd70bc 100644
--- a/bare-metal/container-linux/kubernetes/variables.tf
+++ b/bare-metal/container-linux/kubernetes/variables.tf
@@ -70,6 +70,7 @@ variable "ssh_authorized_key" {
 variable "asset_dir" {
   type        = string
   description = "Absolute path to a directory where generated assets should be placed (contains secrets)"
+  default     = ""
 }
 
 variable "networking" {
diff --git a/bare-metal/fedora-coreos/kubernetes/variables.tf b/bare-metal/fedora-coreos/kubernetes/variables.tf
index 159c751c..8e956754 100644
--- a/bare-metal/fedora-coreos/kubernetes/variables.tf
+++ b/bare-metal/fedora-coreos/kubernetes/variables.tf
@@ -71,6 +71,7 @@ variable "ssh_authorized_key" {
 variable "asset_dir" {
   type        = string
   description = "Absolute path to a directory where generated assets should be placed (contains secrets)"
+  default     = ""
 }
 
 variable "networking" {
diff --git a/digital-ocean/container-linux/kubernetes/variables.tf b/digital-ocean/container-linux/kubernetes/variables.tf
index b347e3cf..0c25d379 100644
--- a/digital-ocean/container-linux/kubernetes/variables.tf
+++ b/digital-ocean/container-linux/kubernetes/variables.tf
@@ -69,6 +69,7 @@ variable "ssh_fingerprints" {
 variable "asset_dir" {
   type        = string
   description = "Absolute path to a directory where generated assets should be placed (contains secrets)"
+  default     = ""
 }
 
 variable "networking" {
diff --git a/docs/addons/ingress.md b/docs/addons/ingress.md
index 4bbbfbe1..14689c37 100644
--- a/docs/addons/ingress.md
+++ b/docs/addons/ingress.md
@@ -31,7 +31,7 @@ resource "google_dns_record_set" "some-application" {
   name    = "app.example.com."
   type    = "CNAME"
   ttl     = 300
-  rrdatas = ["${module.aws-tempest.ingress_dns_name}."]
+  rrdatas = ["${module.tempest.ingress_dns_name}."]
 }
 ```
 
@@ -64,7 +64,7 @@ resource "google_dns_record_set" "some-application" {
   name    = "app.example.com."
   type    = "A"
   ttl     = 300
-  rrdatas = [module.azure-ramius.ingress_static_ipv4]
+  rrdatas = [module.ramius.ingress_static_ipv4]
 }
 ```
 
@@ -120,7 +120,7 @@ resource "google_dns_record_set" "some-application" {
   name    = "app.example.com."
   type    = "CNAME"
   ttl     = 300
-  rrdatas = ["${module.digital-ocean-nemo.workers_dns}."]
+  rrdatas = ["${module.nemo.workers_dns}."]
 }
 ```
 
@@ -158,7 +158,7 @@ resource "google_dns_record_set" "app-record-a" {
   name    = "app.example.com."
   type    = "A"
   ttl     = 300
-  rrdatas = [module.google-cloud-yavin.ingress_static_ipv4]
+  rrdatas = [module.yavin.ingress_static_ipv4]
 }
 
 resource "google_dns_record_set" "app-record-aaaa" {
@@ -169,6 +169,6 @@ resource "google_dns_record_set" "app-record-aaaa" {
   name    = "app.example.com."
   type    = "AAAA"
   ttl     = 300
-  rrdatas = [module.google-cloud-yavin.ingress_static_ipv6]
+  rrdatas = [module.yavin.ingress_static_ipv6]
 }
 ```
diff --git a/docs/advanced/customization.md b/docs/advanced/customization.md
index e9ad8de7..2fd3373f 100644
--- a/docs/advanced/customization.md
+++ b/docs/advanced/customization.md
@@ -72,7 +72,7 @@ Write Container Linux Configs *snippets* as files in the repository where you ke
 [AWS](/cl/aws/#cluster), [Azure](/cl/azure/#cluster), [DigitalOcean](/cl/digital-ocean/#cluster), and [Google Cloud](/cl/google-cloud/#cluster) clusters allow populating a list of `controller_clc_snippets` or `worker_clc_snippets`.
 
 ```
-module "digital-ocean-nemo" {
+module "nemo" {
   ...
 
   controller_count        = 1
@@ -92,7 +92,7 @@ module "digital-ocean-nemo" {
 [Bare-Metal](/cl/bare-metal/#cluster) clusters allow different Container Linux snippets to be used for each node (since hardware may be heterogeneous). Populate the optional `clc_snippets` map variable with any controller or worker name keys and lists of snippets.
 
 ```
-module "bare-metal-mercury" {
+module "mercury" {
   ...
   controller_names = ["node1"]
   worker_names = [
@@ -141,7 +141,7 @@ Container Linux Configs (and the CoreOS Ignition system) create immutable infras
 Typhoon chooses variables to expose with purpose. If you must customize clusters in ways that aren't supported by input variables, fork Typhoon and maintain a repository with customizations. Reference the repository by changing the username.
 
 ```
-module "digital-ocean-nemo" {
+module "nemo" {
   source = "git::https://github.com/USERNAME/typhoon//digital-ocean/container-linux/kubernetes?ref=myspecialcase"
   ...
 }
diff --git a/docs/advanced/worker-pools.md b/docs/advanced/worker-pools.md
index 3eeb4edb..645fc3ee 100644
--- a/docs/advanced/worker-pools.md
+++ b/docs/advanced/worker-pools.md
@@ -17,13 +17,13 @@ module "tempest-worker-pool" {
   source = "git::https://github.com/poseidon/typhoon//aws/container-linux/kubernetes/workers?ref=v1.14.3"
 
   # AWS
-  vpc_id          = module.aws-tempest.vpc_id
-  subnet_ids      = module.aws-tempest.subnet_ids
-  security_groups = module.aws-tempest.worker_security_groups
+  vpc_id          = module.tempest.vpc_id
+  subnet_ids      = module.tempest.subnet_ids
+  security_groups = module.tempest.worker_security_groups
   
   # configuration
   name               = "tempest-pool"
-  kubeconfig         = module.aws-tempest.kubeconfig
+  kubeconfig         = module.tempest.kubeconfig
   ssh_authorized_key = var.ssh_authorized_key
 
   # optional
@@ -82,15 +82,15 @@ module "ramius-worker-pool" {
   source = "git::https://github.com/poseidon/typhoon//azure/container-linux/kubernetes/workers?ref=v1.16.3"
   
   # Azure
-  region                  = module.azure-ramius.region
-  resource_group_name     = module.azure-ramius.resource_group_name
-  subnet_id               = module.azure-ramius.subnet_id
-  security_group_id       = module.azure-ramius.security_group_id
-  backend_address_pool_id = module.azure-ramius.backend_address_pool_id
+  region                  = module.ramius.region
+  resource_group_name     = module.ramius.resource_group_name
+  subnet_id               = module.ramius.subnet_id
+  security_group_id       = module.ramius.security_group_id
+  backend_address_pool_id = module.ramius.backend_address_pool_id
 
   # configuration
   name               = "ramius-low-priority"
-  kubeconfig         = module.azure-ramius.kubeconfig
+  kubeconfig         = module.ramius.kubeconfig
   ssh_authorized_key = var.ssh_authorized_key
 
   # optional
@@ -149,12 +149,12 @@ module "yavin-worker-pool" {
 
   # Google Cloud
   region       = "europe-west2"
-  network      = module.google-cloud-yavin.network_name
+  network      = module.yavin.network_name
   cluster_name = "yavin"
 
   # configuration
   name               = "yavin-16x"
-  kubeconfig         = module.google-cloud-yavin.kubeconfig
+  kubeconfig         = module.yavin.kubeconfig
   ssh_authorized_key = var.ssh_authorized_key
   
   # optional
diff --git a/docs/architecture/concepts.md b/docs/architecture/concepts.md
index 255ab02f..dda1a600 100644
--- a/docs/architecture/concepts.md
+++ b/docs/architecture/concepts.md
@@ -47,7 +47,7 @@ Terraform [modules](https://www.terraform.io/docs/modules/usage.html) allow a co
 Clusters are declared in Terraform by referencing the module.
 
 ```tf
-module "google-cloud-yavin" {
+module "yavin" {
   source = "git::https://github.com/poseidon/typhoon//google-cloud/container-linux/kubernetes"
   cluster_name = "yavin"
   ...
diff --git a/docs/cl/aws.md b/docs/cl/aws.md
index 3bf2244e..52c046dc 100644
--- a/docs/cl/aws.md
+++ b/docs/cl/aws.md
@@ -79,7 +79,6 @@ module "tempest" {
 
   # configuration
   ssh_authorized_key = "ssh-rsa AAAAB3Nz..."
-  asset_dir          = "/home/user/.secrets/clusters/tempest"
 
   # optional
   worker_count = 2
@@ -118,9 +117,9 @@ Apply the changes to create the cluster.
 ```sh
 $ terraform apply
 ...
-module.aws-tempest.null_resource.bootstrap: Still creating... (4m50s elapsed)
-module.aws-tempest.null_resource.bootstrap: Still creating... (5m0s elapsed)
-module.aws-tempest.null_resource.bootstrap: Creation complete after 11m8s (ID: 3961816482286168143)
+module.tempest.null_resource.bootstrap: Still creating... (4m50s elapsed)
+module.tempest.null_resource.bootstrap: Still creating... (5m0s elapsed)
+module.tempest.null_resource.bootstrap: Creation complete after 11m8s (ID: 3961816482286168143)
 
 Apply complete! Resources: 98 added, 0 changed, 0 destroyed.
 ```
@@ -129,10 +128,19 @@ In 4-8 minutes, the Kubernetes cluster will be ready.
 
 ## Verify
 
-[Install kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) on your system. Use the generated `kubeconfig` credentials to access the Kubernetes cluster and list nodes.
+[Install kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) on your system. Obtain the generated cluster `kubeconfig` from module outputs (e.g. write to a local file).
 
 ```
-$ export KUBECONFIG=/home/user/.secrets/clusters/tempest/auth/kubeconfig
+resource "local_file" "kubeconfig-tempest" {
+  content  = module.tempest.kubeconfig-admin
+  filename = "/home/user/.kube/configs/tempest-config"
+}
+```
+
+List nodes in the cluster.
+
+```
+$ export KUBECONFIG=/home/user/.kube/configs/tempest-config
 $ kubectl get nodes
 NAME           STATUS  ROLES   AGE  VERSION
 ip-10-0-3-155  Ready   <none>  10m  v1.16.3
@@ -177,7 +185,6 @@ Check the [variables.tf](https://github.com/poseidon/typhoon/blob/master/aws/con
 | dns_zone | AWS Route53 DNS zone | "aws.example.com" |
 | dns_zone_id | AWS Route53 DNS zone id | "Z3PAABBCFAKEC0" |
 | ssh_authorized_key | SSH public key for user 'core' | "ssh-rsa AAAAB3NZ..." |
-| asset_dir | Absolute path to a directory where generated assets should be placed (contains secrets) | "/home/user/.secrets/clusters/tempest" |
 
 #### DNS Zone
 
@@ -200,6 +207,7 @@ Reference the DNS zone id with `aws_route53_zone.zone-for-clusters.zone_id`.
 
 | Name | Description | Default | Example |
 |:-----|:------------|:--------|:--------|
+| asset_dir | Absolute path to a directory where generated assets should be placed (contains secrets) | "" (disabled) | "/home/user/.secrets/clusters/tempest" |
 | controller_count | Number of controllers (i.e. masters) | 1 | 1 |
 | worker_count | Number of workers | 1 | 3 |
 | controller_type | EC2 instance type for controllers | "t3.small" | See below |
diff --git a/docs/cl/azure.md b/docs/cl/azure.md
index dc334fba..f2afd815 100644
--- a/docs/cl/azure.md
+++ b/docs/cl/azure.md
@@ -76,7 +76,6 @@ module "ramius" {
 
   # configuration
   ssh_authorized_key = "ssh-rsa AAAAB3Nz..."
-  asset_dir          = "/home/user/.secrets/clusters/ramius"
 
   # optional
   worker_count    = 2
@@ -115,9 +114,9 @@ Apply the changes to create the cluster.
 ```sh
 $ terraform apply
 ...
-module.azure-ramius.null_resource.bootstrap: Still creating... (6m50s elapsed)
-module.azure-ramius.null_resource.bootstrap: Still creating... (7m0s elapsed)
-module.azure-ramius.null_resource.bootstrap: Creation complete after 7m8s (ID: 3961816482286168143)
+module.ramius.null_resource.bootstrap: Still creating... (6m50s elapsed)
+module.ramius.null_resource.bootstrap: Still creating... (7m0s elapsed)
+module.ramius.null_resource.bootstrap: Creation complete after 7m8s (ID: 3961816482286168143)
 
 Apply complete! Resources: 86 added, 0 changed, 0 destroyed.
 ```
@@ -126,10 +125,19 @@ In 4-8 minutes, the Kubernetes cluster will be ready.
 
 ## Verify
 
-[Install kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) on your system. Use the generated `kubeconfig` credentials to access the Kubernetes cluster and list nodes.
+[Install kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) on your system. Obtain the generated cluster `kubeconfig` from module outputs (e.g. write to a local file).
 
 ```
-$ export KUBECONFIG=/home/user/.secrets/clusters/ramius/auth/kubeconfig
+resource "local_file" "kubeconfig-ramius" {
+  content  = module.ramius.kubeconfig-admin
+  filename = "/home/user/.kube/configs/ramius-config"
+}
+```
+
+List nodes in the cluster.
+
+```
+$ export KUBECONFIG=/home/user/.kube/configs/ramius-config
 $ kubectl get nodes
 NAME                  STATUS  ROLES   AGE  VERSION
 ramius-controller-0   Ready   <none>  24m  v1.16.3
@@ -175,7 +183,6 @@ Check the [variables.tf](https://github.com/poseidon/typhoon/blob/master/azure/c
 | dns_zone | Azure DNS zone | "azure.example.com" |
 | dns_zone_group | Resource group where the Azure DNS zone resides | "global" |
 | ssh_authorized_key | SSH public key for user 'core' | "ssh-rsa AAAAB3NZ..." |
-| asset_dir | Absolute path to a directory where generated assets should be placed (contains secrets) | "/home/user/.secrets/clusters/ramius" |
 
 !!! tip
     Regions are shown in [docs](https://azure.microsoft.com/en-us/global-infrastructure/regions/) or with `az account list-locations --output table`.
@@ -211,6 +218,7 @@ Reference the DNS zone with `azurerm_dns_zone.clusters.name` and its resource gr
 
 | Name | Description | Default | Example |
 |:-----|:------------|:--------|:--------|
+| asset_dir | Absolute path to a directory where generated assets should be placed (contains secrets) | "" (disabled) | "/home/user/.secrets/clusters/ramius" |
 | controller_count | Number of controllers (i.e. masters) | 1 | 1 |
 | worker_count | Number of workers | 1 | 3 |
 | controller_type | Machine type for controllers | "Standard_B2s" | See below |
diff --git a/docs/cl/bare-metal.md b/docs/cl/bare-metal.md
index 8d9e9122..b67930b4 100644
--- a/docs/cl/bare-metal.md
+++ b/docs/cl/bare-metal.md
@@ -159,7 +159,7 @@ provider "ct" {
 Define a Kubernetes cluster using the module `bare-metal/container-linux/kubernetes`.
 
 ```tf
-module "bare-metal-mercury" {
+module "mercury" {
   source = "git::https://github.com/poseidon/typhoon//bare-metal/container-linux/kubernetes?ref=v1.16.3"
   
   # bare-metal
@@ -171,7 +171,6 @@ module "bare-metal-mercury" {
   # configuration
   k8s_domain_name    = "node1.example.com"
   ssh_authorized_key = "ssh-rsa AAAAB3Nz..."
-  asset_dir          = "/home/user/.secrets/clusters/mercury"
 
   # machines
   controllers = [{
@@ -223,12 +222,12 @@ $ terraform plan
 Plan: 55 to add, 0 to change, 0 to destroy.
 ```
 
-Apply the changes. Terraform will generate bootstrap assets to `asset_dir` and create Matchbox profiles (e.g. controller, worker) and matching rules via the Matchbox API.
+Apply the changes. Terraform will generate bootstrap assets and create Matchbox profiles (e.g. controller, worker) and matching rules via the Matchbox API.
 
 ```sh
 $ terraform apply
-module.bare-metal-mercury.null_resource.copy-controller-secrets.0: Still creating... (10s elapsed)
-module.bare-metal-mercury.null_resource.copy-worker-secrets.0: Still creating... (10s elapsed)
+module.mercury.null_resource.copy-controller-secrets.0: Still creating... (10s elapsed)
+module.mercury.null_resource.copy-worker-secrets.0: Still creating... (10s elapsed)
 ...
 ```
 
@@ -253,11 +252,11 @@ Machines will network boot, install Container Linux to disk, reboot into the dis
 Wait for the `bootstrap` step to finish bootstrapping the Kubernetes control plane. This may take 5-15 minutes depending on your network.
 
 ```
-module.bare-metal-mercury.null_resource.bootstrap: Still creating... (6m10s elapsed)
-module.bare-metal-mercury.null_resource.bootstrap: Still creating... (6m20s elapsed)
-module.bare-metal-mercury.null_resource.bootstrap: Still creating... (6m30s elapsed)
-module.bare-metal-mercury.null_resource.bootstrap: Still creating... (6m40s elapsed)
-module.bare-metal-mercury.null_resource.bootstrap: Creation complete (ID: 5441741360626669024)
+module.mercury.null_resource.bootstrap: Still creating... (6m10s elapsed)
+module.mercury.null_resource.bootstrap: Still creating... (6m20s elapsed)
+module.mercury.null_resource.bootstrap: Still creating... (6m30s elapsed)
+module.mercury.null_resource.bootstrap: Still creating... (6m40s elapsed)
+module.mercury.null_resource.bootstrap: Creation complete (ID: 5441741360626669024)
 
 Apply complete! Resources: 55 added, 0 changed, 0 destroyed.
 ```
@@ -276,19 +275,28 @@ To watch the bootstrap process in detail, SSH to the first controller and journa
 ```
 $ ssh core@node1.example.com
 $ journalctl -f -u bootstrap
-podman[1750]: The connection to the server cluster.example.com:6443 was refused - did you specify the right host or port?
-podman[1750]: Waiting for static pod control plane
+rkt[1750]: The connection to the server cluster.example.com:6443 was refused - did you specify the right host or port?
+rkt[1750]: Waiting for static pod control plane
 ...
-podman[1750]: serviceaccount/calico-node unchanged
+rkt[1750]: serviceaccount/calico-node unchanged
 systemd[1]: Started Kubernetes control plane.
 ```
 
 ## Verify
 
-[Install kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) on your system. Use the generated `kubeconfig` credentials to access the Kubernetes cluster and list nodes.
+[Install kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) on your system. Obtain the generated cluster `kubeconfig` from module outputs (e.g. write to a local file).
 
 ```
-$ export KUBECONFIG=/home/user/.secrets/clusters/mercury/auth/kubeconfig
+resource "local_file" "kubeconfig-mercury" {
+  content  = module.mercury.kubeconfig-admin
+  filename = "/home/user/.kube/configs/mercury-config"
+}
+```
+
+List nodes in the cluster.
+
+```
+$ export KUBECONFIG=/home/user/.kube/configs/mercury-config
 $ kubectl get nodes
 NAME                STATUS  ROLES   AGE  VERSION
 node1.example.com   Ready   <none>  10m  v1.16.3
@@ -335,7 +343,6 @@ Check the [variables.tf](https://github.com/poseidon/typhoon/blob/master/bare-me
 | os_version | Version for a Container Linux derivative to PXE and install | "1632.3.0" |
 | k8s_domain_name | FQDN resolving to the controller(s) nodes. Workers and kubectl will communicate with this endpoint | "myk8s.example.com" |
 | ssh_authorized_key | SSH public key for user 'core' | "ssh-rsa AAAAB3Nz..." |
-| asset_dir | Absolute path to a directory where generated assets should be placed (contains secrets) | "/home/user/.secrets/clusters/mercury" |
 | controllers | List of controller machine detail objects (unique name, identifying MAC address, FQDN) | `[{name="node1", mac="52:54:00:a1:9c:ae", domain="node1.example.com"}]` |
 | workers | List of worker machine detail objects (unique name, identifying MAC address, FQDN) | `[{name="node2", mac="52:54:00:b2:2f:86", domain="node2.example.com"}, {name="node3", mac="52:54:00:c3:61:77", domain="node3.example.com"}]` |
 
@@ -343,6 +350,7 @@ Check the [variables.tf](https://github.com/poseidon/typhoon/blob/master/bare-me
 
 | Name | Description | Default | Example |
 |:-----|:------------|:--------|:--------|
+| asset_dir | Absolute path to a directory where generated assets should be placed (contains secrets) | "" (disabled) | "/home/user/.secrets/clusters/mercury" |
 | download_protocol | Protocol iPXE uses to download the kernel and initrd. iPXE must be compiled with [crypto](https://ipxe.org/crypto) support for https. Unused if cached_install is true | "https" | "http" |
 | cached_install | PXE boot and install from the Matchbox `/assets` cache. Admin MUST have downloaded Container Linux or Flatcar images into the cache | false | true |
 | install_disk | Disk device where Container Linux should be installed | "/dev/sda" | "/dev/sdb" |
diff --git a/docs/cl/digital-ocean.md b/docs/cl/digital-ocean.md
index 4dea64f3..973bd524 100644
--- a/docs/cl/digital-ocean.md
+++ b/docs/cl/digital-ocean.md
@@ -64,7 +64,7 @@ provider "ct" {
 Define a Kubernetes cluster using the module `digital-ocean/container-linux/kubernetes`.
 
 ```tf
-module "digital-ocean-nemo" {
+module "nemo" {
   source = "git::https://github.com/poseidon/typhoon//digital-ocean/container-linux/kubernetes?ref=v1.16.3"
 
   # Digital Ocean
@@ -74,7 +74,6 @@ module "digital-ocean-nemo" {
 
   # configuration
   ssh_fingerprints = ["d7:9d:79:ae:56:32:73:79:95:88:e3:a2:ab:5d:45:e7"]
-  asset_dir        = "/home/user/.secrets/clusters/nemo"
   
   # optional
   worker_count = 2
@@ -111,11 +110,11 @@ Apply the changes to create the cluster.
 
 ```sh
 $ terraform apply
-module.digital-ocean-nemo.null_resource.bootstrap: Still creating... (30s elapsed)
-module.digital-ocean-nemo.null_resource.bootstrap: Provisioning with 'remote-exec'...
+module.nemo.null_resource.bootstrap: Still creating... (30s elapsed)
+module.nemo.null_resource.bootstrap: Provisioning with 'remote-exec'...
 ...
-module.digital-ocean-nemo.null_resource.bootstrap: Still creating... (6m20s elapsed)
-module.digital-ocean-nemo.null_resource.bootstrap: Creation complete (ID: 7599298447329218468)
+module.nemo.null_resource.bootstrap: Still creating... (6m20s elapsed)
+module.nemo.null_resource.bootstrap: Creation complete (ID: 7599298447329218468)
 
 Apply complete! Resources: 54 added, 0 changed, 0 destroyed.
 ```
@@ -124,10 +123,19 @@ In 3-6 minutes, the Kubernetes cluster will be ready.
 
 ## Verify
 
-[Install kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) on your system. Use the generated `kubeconfig` credentials to access the Kubernetes cluster and list nodes.
+[Install kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) on your system. Obtain the generated cluster `kubeconfig` from module outputs (e.g. write to a local file).
 
 ```
-$ export KUBECONFIG=/home/user/.secrets/clusters/nemo/auth/kubeconfig
+resource "local_file" "kubeconfig-nemo" {
+  content  = module.nemo.kubeconfig-admin
+  filename = "/home/user/.kube/configs/nemo-config"
+}
+```
+
+List nodes in the cluster.
+
+```
+$ export KUBECONFIG=/home/user/.kube/configs/nemo-config
 $ kubectl get nodes
 NAME               STATUS  ROLES   AGE  VERSION
 10.132.110.130     Ready   <none>  10m  v1.16.3
@@ -171,7 +179,6 @@ Check the [variables.tf](https://github.com/poseidon/typhoon/blob/master/digital
 | region | Digital Ocean region | "nyc1", "sfo2", "fra1", tor1" |
 | dns_zone | Digital Ocean domain (i.e. DNS zone) | "do.example.com" |
 | ssh_fingerprints | SSH public key fingerprints | ["d7:9d..."] |
-| asset_dir | Absolute path to a directory where generated assets should be placed (contains secrets) | "/home/user/.secrets/nemo" |
 
 #### DNS Zone
 
@@ -212,6 +219,7 @@ Digital Ocean requires the SSH public key be uploaded to your account, so you ma
 
 | Name | Description | Default | Example |
 |:-----|:------------|:--------|:--------|
+| asset_dir | Absolute path to a directory where generated assets should be placed (contains secrets) | "" (disabled) | "/home/user/.secrets/nemo" |
 | controller_count | Number of controllers (i.e. masters) | 1 | 1 |
 | worker_count | Number of workers | 1 | 3 |
 | controller_type | Droplet type for controllers | "s-2vcpu-2gb" | s-2vcpu-2gb, s-2vcpu-4gb, s-4vcpu-8gb, ... |
diff --git a/docs/cl/google-cloud.md b/docs/cl/google-cloud.md
index bbe91a24..243b437a 100644
--- a/docs/cl/google-cloud.md
+++ b/docs/cl/google-cloud.md
@@ -70,7 +70,7 @@ Additional configuration options are described in the `google` provider [docs](h
 Define a Kubernetes cluster using the module `google-cloud/container-linux/kubernetes`.
 
 ```tf
-module "google-cloud-yavin" {
+module "yavin" {
   source = "git::https://github.com/poseidon/typhoon//google-cloud/container-linux/kubernetes?ref=v1.16.3"
 
   # Google Cloud
@@ -81,7 +81,6 @@ module "google-cloud-yavin" {
 
   # configuration
   ssh_authorized_key = "ssh-rsa AAAAB3Nz..."
-  asset_dir          = "/home/user/.secrets/clusters/yavin"
   
   # optional
   worker_count = 2
@@ -118,11 +117,11 @@ Apply the changes to create the cluster.
 
 ```sh
 $ terraform apply
-module.google-cloud-yavin.null_resource.bootstrap: Still creating... (10s elapsed)
+module.yavin.null_resource.bootstrap: Still creating... (10s elapsed)
 ...
-module.google-cloud-yavin.null_resource.bootstrap: Still creating... (5m30s elapsed)
-module.google-cloud-yavin.null_resource.bootstrap: Still creating... (5m40s elapsed)
-module.google-cloud-yavin.null_resource.bootstrap: Creation complete (ID: 5768638456220583358)
+module.yavin.null_resource.bootstrap: Still creating... (5m30s elapsed)
+module.yavin.null_resource.bootstrap: Still creating... (5m40s elapsed)
+module.yavin.null_resource.bootstrap: Creation complete (ID: 5768638456220583358)
 
 Apply complete! Resources: 64 added, 0 changed, 0 destroyed.
 ```
@@ -131,10 +130,19 @@ In 4-8 minutes, the Kubernetes cluster will be ready.
 
 ## Verify
 
-[Install kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) on your system. Use the generated `kubeconfig` credentials to access the Kubernetes cluster and list nodes.
+[Install kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) on your system. Obtain the generated cluster `kubeconfig` from module outputs (e.g. write to a local file).
 
 ```
-$ export KUBECONFIG=/home/user/.secrets/clusters/yavin/auth/kubeconfig
+resource "local_file" "kubeconfig-yavin" {
+  content  = module.yavin.kubeconfig-admin
+  filename = "/home/user/.kube/configs/yavin-config"
+}
+```
+
+List nodes in the cluster.
+
+```
+$ export KUBECONFIG=/home/user/.kube/configs/yavin-config
 $ kubectl get nodes
 NAME                                       ROLES    STATUS  AGE  VERSION
 yavin-controller-0.c.example-com.internal  <none>   Ready   6m   v1.16.3
@@ -180,7 +188,6 @@ Check the [variables.tf](https://github.com/poseidon/typhoon/blob/master/google-
 | dns_zone | Google Cloud DNS zone | "google-cloud.example.com" |
 | dns_zone_name | Google Cloud DNS zone name | "example-zone" |
 | ssh_authorized_key | SSH public key for user 'core' | "ssh-rsa AAAAB3NZ..." |
-| asset_dir | Absolute path to a directory where generated assets should be placed (contains secrets) | "/home/user/.secrets/clusters/yavin" |
 
 Check the list of valid [regions](https://cloud.google.com/compute/docs/regions-zones/regions-zones) and list Container Linux [images](https://cloud.google.com/compute/docs/images) with `gcloud compute images list | grep coreos`.
 
@@ -205,6 +212,7 @@ resource "google_dns_managed_zone" "zone-for-clusters" {
 
 | Name | Description | Default | Example |
 |:-----|:------------|:--------|:--------|
+| asset_dir | Absolute path to a directory where generated assets should be placed (contains secrets) | "" (disabled) | "/home/user/.secrets/clusters/yavin" |
 | controller_count | Number of controllers (i.e. masters) | 1 | 3 |
 | worker_count | Number of workers | 1 | 3 |
 | controller_type | Machine type for controllers | "n1-standard-1" | See below |
diff --git a/docs/fedora-coreos/aws.md b/docs/fedora-coreos/aws.md
index 6c0de1f9..b0f35a12 100644
--- a/docs/fedora-coreos/aws.md
+++ b/docs/fedora-coreos/aws.md
@@ -72,7 +72,7 @@ Additional configuration options are described in the `aws` provider [docs](http
 Define a Kubernetes cluster using the module `aws/fedora-coreos/kubernetes`.
 
 ```tf
-module "aws-tempest" {
+module "tempest" {
   source = "git::https://github.com/poseidon/typhoon//aws/fedora-coreos/kubernetes?ref=v1.16.3"
 
   # AWS
@@ -82,7 +82,6 @@ module "aws-tempest" {
 
   # configuration
   ssh_authorized_key = "ssh-rsa AAAAB3Nz..."
-  asset_dir          = "/home/user/.secrets/clusters/tempest"
 
   # optional
   worker_count = 2
@@ -121,9 +120,9 @@ Apply the changes to create the cluster.
 ```sh
 $ terraform apply
 ...
-module.aws-tempest.null_resource.bootstrap: Still creating... (4m50s elapsed)
-module.aws-tempest.null_resource.bootstrap: Still creating... (5m0s elapsed)
-module.aws-tempest.null_resource.bootstrap: Creation complete after 5m8s (ID: 3961816482286168143)
+module.tempest.null_resource.bootstrap: Still creating... (4m50s elapsed)
+module.tempest.null_resource.bootstrap: Still creating... (5m0s elapsed)
+module.tempest.null_resource.bootstrap: Creation complete after 5m8s (ID: 3961816482286168143)
 
 Apply complete! Resources: 98 added, 0 changed, 0 destroyed.
 ```
@@ -132,10 +131,19 @@ In 4-8 minutes, the Kubernetes cluster will be ready.
 
 ## Verify
 
-[Install kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) on your system. Use the generated `kubeconfig` credentials to access the Kubernetes cluster and list nodes.
+[Install kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) on your system. Obtain the generated cluster `kubeconfig` from module outputs (e.g. write to a local file).
 
 ```
-$ export KUBECONFIG=/home/user/.secrets/clusters/tempest/auth/kubeconfig
+resource "local_file" "kubeconfig-tempest" {
+  content  = module.tempest.kubeconfig-admin
+  filename = "/home/user/.kube/configs/tempest-config"
+}
+```
+
+List nodes in the cluster.
+
+```
+$ export KUBECONFIG=/home/user/.kube/configs/tempest-config
 $ kubectl get nodes
 NAME           STATUS  ROLES    AGE  VERSION
 ip-10-0-3-155  Ready   <none>   10m  v1.16.3
@@ -177,7 +185,6 @@ Check the [variables.tf](https://github.com/poseidon/typhoon/blob/master/aws/fed
 | dns_zone | AWS Route53 DNS zone | "aws.example.com" |
 | dns_zone_id | AWS Route53 DNS zone id | "Z3PAABBCFAKEC0" |
 | ssh_authorized_key | SSH public key for user 'core' | "ssh-rsa AAAAB3NZ..." |
-| asset_dir | Absolute path to a directory where generated assets should be placed (contains secrets) | "/home/user/.secrets/clusters/tempest" |
 
 #### DNS Zone
 
@@ -200,6 +207,7 @@ Reference the DNS zone id with `aws_route53_zone.zone-for-clusters.zone_id`.
 
 | Name | Description | Default | Example |
 |:-----|:------------|:--------|:--------|
+| asset_dir | Absolute path to a directory where generated assets should be placed (contains secrets) | "" (disabled) | "/home/user/.secrets/clusters/tempest" |
 | controller_count | Number of controllers (i.e. masters) | 1 | 1 |
 | worker_count | Number of workers | 1 | 3 |
 | controller_type | EC2 instance type for controllers | "t3.small" | See below |
diff --git a/docs/fedora-coreos/bare-metal.md b/docs/fedora-coreos/bare-metal.md
index a832fdd0..056f24b4 100644
--- a/docs/fedora-coreos/bare-metal.md
+++ b/docs/fedora-coreos/bare-metal.md
@@ -162,7 +162,7 @@ provider "ct" {
 Define a Kubernetes cluster using the module `bare-metal/fedora-coreos/kubernetes`.
 
 ```tf
-module "bare-metal-mercury" {
+module "mercury" {
   source = "git::https://github.com/poseidon/typhoon//bare-metal/fedora-coreos/kubernetes?ref=v1.16.3"
   
   # bare-metal
@@ -175,7 +175,6 @@ module "bare-metal-mercury" {
   # configuration
   k8s_domain_name    = "node1.example.com"
   ssh_authorized_key = "ssh-rsa AAAAB3Nz..."
-  asset_dir          = "/home/user/.secrets/clusters/mercury"
 
   # machines
   controllers = [{
@@ -224,14 +223,14 @@ $ terraform plan
 Plan: 55 to add, 0 to change, 0 to destroy.
 ```
 
-Apply the changes. Terraform will generate bootstrap assets to `asset_dir` and create Matchbox profiles (e.g. controller, worker) and matching rules via the Matchbox API.
+Apply the changes. Terraform will generate bootstrap assets and create Matchbox profiles (e.g. controller, worker) and matching rules via the Matchbox API.
 
 ```sh
 $ terraform apply
-module.bare-metal-mercury.null_resource.copy-kubeconfig.0: Provisioning with 'file'...
-module.bare-metal-mercury.null_resource.copy-etcd-secrets.0: Provisioning with 'file'...
-module.bare-metal-mercury.null_resource.copy-kubeconfig.0: Still creating... (10s elapsed)
-module.bare-metal-mercury.null_resource.copy-etcd-secrets.0: Still creating... (10s elapsed)
+module.mercury.null_resource.copy-kubeconfig.0: Provisioning with 'file'...
+module.mercury.null_resource.copy-etcd-secrets.0: Provisioning with 'file'...
+module.mercury.null_resource.copy-kubeconfig.0: Still creating... (10s elapsed)
+module.mercury.null_resource.copy-etcd-secrets.0: Still creating... (10s elapsed)
 ...
 ```
 
@@ -256,11 +255,11 @@ Machines will network boot, install Fedora CoreOS to disk, reboot into the disk
 Wait for the `bootstrap` step to finish bootstrapping the Kubernetes control plane. This may take 5-15 minutes depending on your network.
 
 ```
-module.bare-metal-mercury.null_resource.bootstrap: Still creating... (6m10s elapsed)
-module.bare-metal-mercury.null_resource.bootstrap: Still creating... (6m20s elapsed)
-module.bare-metal-mercury.null_resource.bootstrap: Still creating... (6m30s elapsed)
-module.bare-metal-mercury.null_resource.bootstrap: Still creating... (6m40s elapsed)
-module.bare-metal-mercury.null_resource.bootstrap: Creation complete (ID: 5441741360626669024)
+module.mercury.null_resource.bootstrap: Still creating... (6m10s elapsed)
+module.mercury.null_resource.bootstrap: Still creating... (6m20s elapsed)
+module.mercury.null_resource.bootstrap: Still creating... (6m30s elapsed)
+module.mercury.null_resource.bootstrap: Still creating... (6m40s elapsed)
+module.mercury.null_resource.bootstrap: Creation complete (ID: 5441741360626669024)
 
 Apply complete! Resources: 55 added, 0 changed, 0 destroyed.
 ```
@@ -279,10 +278,19 @@ systemd[1]: Started Kubernetes control plane.
 
 ## Verify
 
-[Install kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) on your system. Use the generated `kubeconfig` credentials to access the Kubernetes cluster and list nodes.
+[Install kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) on your system. Obtain the generated cluster `kubeconfig` from module outputs (e.g. write to a local file).
 
 ```
-$ export KUBECONFIG=/home/user/.secrets/clusters/mercury/auth/kubeconfig
+resource "local_file" "kubeconfig-mercury" {
+  content  = module.mercury.kubeconfig-admin
+  filename = "/home/user/.kube/configs/mercury-config"
+}
+```
+
+List nodes in the cluster.
+
+```
+$ export KUBECONFIG=/home/user/.kube/configs/mercury-config
 $ kubectl get nodes
 NAME                STATUS  ROLES   AGE  VERSION
 node1.example.com   Ready   <none>  10m  v1.16.3
@@ -326,7 +334,6 @@ Check the [variables.tf](https://github.com/poseidon/typhoon/blob/master/bare-me
 | os_version | Fedora CoreOS version to PXE and install | "30.20190716.1" |
 | k8s_domain_name | FQDN resolving to the controller(s) nodes. Workers and kubectl will communicate with this endpoint | "myk8s.example.com" |
 | ssh_authorized_key | SSH public key for user 'core' | "ssh-rsa AAAAB3Nz..." |
-| asset_dir | Absolute path to a directory where generated assets should be placed (contains secrets) | "/home/user/.secrets/clusters/mercury" |
 | controllers | List of controller machine detail objects (unique name, identifying MAC address, FQDN) | `[{name="node1", mac="52:54:00:a1:9c:ae", domain="node1.example.com"}]` |
 | workers | List of worker machine detail objects (unique name, identifying MAC address, FQDN) | `[{name="node2", mac="52:54:00:b2:2f:86", domain="node2.example.com"}, {name="node3", mac="52:54:00:c3:61:77", domain="node3.example.com"}]` |
 
@@ -334,6 +341,7 @@ Check the [variables.tf](https://github.com/poseidon/typhoon/blob/master/bare-me
 
 | Name | Description | Default | Example |
 |:-----|:------------|:--------|:--------|
+| asset_dir | Absolute path to a directory where generated assets should be placed (contains secrets) | "" (disabled) | "/home/user/.secrets/clusters/mercury" |
 | cached_install | PXE boot and install from the Matchbox `/assets` cache. Admin MUST have downloaded Fedora CoreOS images into the cache | false | true |
 | install_disk | Disk device where Fedora CoreOS should be installed | "sda" (not "/dev/sda" like Container Linux) | "sdb" |
 | networking | Choice of networking provider | "calico" | "calico" or "flannel" |
diff --git a/docs/index.md b/docs/index.md
index 32c52cad..45c2a0e6 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -46,7 +46,7 @@ A preview of Typhoon for [Fedora CoreOS](https://getfedora.org/coreos/) is avail
 Define a Kubernetes cluster by using the Terraform module for your chosen platform and operating system. Here's a minimal example.
 
 ```tf
-module "google-cloud-yavin" {
+module "yavin" {
   source = "git::https://github.com/poseidon/typhoon//google-cloud/container-linux/kubernetes?ref=v1.16.3"
 
   # Google Cloud
@@ -57,11 +57,16 @@ module "google-cloud-yavin" {
 
   # configuration
   ssh_authorized_key = "ssh-rsa AAAAB3Nz..."
-  asset_dir          = "/home/user/.secrets/clusters/yavin"
   
   # optional
   worker_count = 2
 }
+
+# Obtain cluster kubeconfig
+resource "local_file" "kubeconfig-yavin" {
+  content  = module.yavin.kubeconfig-admin
+  filename = "/home/user/.kube/configs/yavin-config"
+}
 ```
 
 Initialize modules, plan the changes to be made, and apply the changes.
@@ -77,7 +82,7 @@ Apply complete! Resources: 64 added, 0 changed, 0 destroyed.
 In 4-8 minutes (varies by platform), the cluster will be ready. This Google Cloud example creates a `yavin.example.com` DNS record to resolve to a network load balancer across controller nodes.
 
 ```
-$ export KUBECONFIG=/home/user/.secrets/clusters/yavin/auth/kubeconfig
+$ export KUBECONFIG=/home/user/.kube/configs/yavin-config
 $ kubectl get nodes
 NAME                                       ROLES    STATUS  AGE  VERSION
 yavin-controller-0.c.example-com.internal  <none>   Ready   6m   v1.16.3
diff --git a/docs/topics/maintenance.md b/docs/topics/maintenance.md
index c25544da..9bd6b18f 100644
--- a/docs/topics/maintenance.md
+++ b/docs/topics/maintenance.md
@@ -12,12 +12,12 @@
 Typhoon provides tagged releases to allow clusters to be versioned using ordinary Terraform configs.
 
 ```
-module "google-cloud-yavin" {
+module "yavin" {
   source = "git::https://github.com/poseidon/typhoon//google-cloud/container-linux/kubernetes?ref=v1.8.6"
   ...
 }
 
-module "bare-metal-mercury" {
+module "mercury" {
   source = "git::https://github.com/poseidon/typhoon//bare-metal/container-linux/kubernetes?ref=v1.16.3"
   ...
 }
@@ -65,7 +65,7 @@ ipmitool -H node1.example.com -U USER -P PASS chassis bootdev pxe
 Delete or comment the Terraform config for the cluster.
 
 ```
-- module "bare-metal-mercury" {
+- module "mercury" {
 -   source = "git::https://github.com/poseidon/typhoon//bare-metal/container-linux/kubernetes"
 -   ...
 -}
@@ -93,7 +93,7 @@ kubectl apply -f mercury -R
 Once you're confident in the new cluster, delete the Terraform config for the old cluster.
 
 ```
-- module "google-cloud-yavin" {
+- module "yavin" {
 -   source = "git::https://github.com/poseidon/typhoon//google-cloud/container-linux/kubernetes"
 -   ...
 -}
@@ -261,7 +261,7 @@ terraform apply
 
 # add kubeconfig to new workers
 terraform state list | grep null_resource
-terraform taint -module digital-ocean-nemo null_resource.copy-worker-secrets.N
+terraform taint -module digital-ocean-nemo null_resource.copy-worker-secrets[N]
 terraform apply
 ```
 
@@ -307,7 +307,7 @@ sudo ln -sf ~/Downloads/terraform-0.12.0/terraform /usr/local/bin/terraform12
 For existing Typhoon v1.14.2 or v1.14.3 clusters, edit the Typhoon `ref` to first SHA that introduced Terraform v0.12 support (`3276bf587850218b8f967978a4bf2b05d5f440a2`). The aim is to minimize the diff and convert to using Terraform v0.12.x. For example:
 
 ```tf
- module "bare-metal-mercury" {
+ module "mercury" {
 -  source = "git::https://github.com/poseidon/typhoon//bare-metal/container-linux/kubernetes?ref=v1.14.3"
 +  source = "git::https://github.com/poseidon/typhoon//bare-metal/container-linux/kubernetes?ref=3276bf587850218b8f967978a4bf2b05d5f440a2"
    ...
@@ -316,7 +316,7 @@ For existing Typhoon v1.14.2 or v1.14.3 clusters, edit the Typhoon `ref` to firs
 With Terraform v0.12, Typhoon clusters no longer require the `providers` block (unless you actually need to pass an [aliased provider](https://www.terraform.io/docs/configuration/providers.html#alias-multiple-provider-instances)). A regression in Terraform v0.11 made it neccessary to explicitly pass aliased providers in order for Typhoon to continue to enforce constraints (see [terraform#16824](https://github.com/hashicorp/terraform/issues/16824)). Terraform v0.12 resolves this issue.
 
 ```tf
- module "bare-metal-mercury" {
+ module "mercury" {
    source = "git::https://github.com/poseidon/typhoon//bare-metal/container-linux/kubernetes?ref=3276bf587850218b8f967978a4bf2b05d5f440a2"
 
 -  providers = {
diff --git a/google-cloud/container-linux/kubernetes/variables.tf b/google-cloud/container-linux/kubernetes/variables.tf
index 32a835fa..d8ed8e30 100644
--- a/google-cloud/container-linux/kubernetes/variables.tf
+++ b/google-cloud/container-linux/kubernetes/variables.tf
@@ -86,6 +86,7 @@ variable "ssh_authorized_key" {
 variable "asset_dir" {
   type        = string
   description = "Absolute path to a directory where generated assets should be placed (contains secrets)"
+  default     = ""
 }
 
 variable "networking" {