Terraform Kubernetes Engine Module

This module handles opinionated Google Cloud Platform Kubernetes Engine cluster creation and configuration with Node Pools, IP MASQ, Network Policy, etc.

The resources/services/activations/deletions that this module will create/trigger are:

• Create a GKE cluster with the provided addons
• Create GKE Node Pool(s) with provided configuration and attach to cluster
• Replace the default kube-dns configmap if stub_domains are provided
• Activate network policy if network_policy is true
• Add ip-masq-agent configmap with provided non_masquerade_cidrs if network_policy is true

Usage

There are multiple examples included in the examples folder but simple usage is as follows:

module "gke" {
  source                     = "terraform-google-modules/kubernetes-engine/google"
  project_id                 = "<PROJECT ID>"
  name                       = "gke-test-1"
  region                     = "us-central1"
  zones                      = ["us-central1-a", "us-central1-b", "us-central1-f"]
  network                    = "vpc-01"
  subnetwork                 = "us-central1-01"
  ip_range_pods              = "us-central1-01-gke-01-pods"
  ip_range_services          = "us-central1-01-gke-01-services"
  http_load_balancing        = false
  horizontal_pod_autoscaling = true
  kubernetes_dashboard       = true
  network_policy             = true

  node_pools = [
    {
      name            = "default-node-pool"
      machine_type    = "n1-standard-2"
      min_count       = 1
      max_count       = 100
      disk_size_gb    = 100
      disk_type       = "pd-standard"
      image_type      = "COS"
      auto_repair     = true
      auto_upgrade    = true
      service_account = "project-service-account@<PROJECT ID>.iam.gserviceaccount.com"
      preemptible     = false
    },
  ]

  node_pools_labels = {
    all = {}

    default-node-pool = {
      default-node-pool = "true"
    }
  }

  node_pools_taints = {
    all = []

    default-node-pool = [
      {
        key    = "default-node-pool"
        value  = "true"
        effect = "PREFER_NO_SCHEDULE"
      },
    ]
  }

  node_pools_tags = {
    all = []

    default-node-pool = [
      "default-node-pool",
    ]
  }
}

Then perform the following commands on the root folder:

• terraform init to get the plugins
• terraform plan to see the infrastructure plan
• terraform apply to apply the infrastructure build
• terraform destroy to destroy the built infrastructure

Inputs

Name	Description	Type	Default	Required
description	The description of the cluster	string	``	no
horizontal_pod_autoscaling	Enable horizontal pod autoscaling addon	string	false	no
http_load_balancing	Enable httpload balancer addon	string	true	no
ip_masq_link_local	Whether to masquerade traffic to the link-local prefix (169.254.0.0/16).	string	false	no
ip_masq_resync_interval	The interval at which the agent attempts to sync its ConfigMap file from the disk.	string	60s	no
ip_range_pods	The secondary ip range to use for pods	string	-	yes
ip_range_services	The secondary ip range to use for pods	string	-	yes
kubernetes_dashboard	Enable kubernetes dashboard addon	string	false	no
kubernetes_version	The Kubernetes version of the masters. If set to 'latest' it will pull latest available version in the selected region.	string	latest	no
logging_service	The logging service that the cluster should write logs to. Available options include logging.googleapis.com, logging.googleapis.com/kubernetes (beta), and none	string	logging.googleapis.com	no
maintenance_start_time	Time window specified for daily maintenance operations in RFC3339 format	string	05:00	no
master_authorized_networks_config	The desired configuration options for master authorized networks. Omit the nested cidr_blocks attribute to disallow external access (except the cluster node IPs, which GKE automatically whitelists) ### example format ### master_authorized_networks_config = [{ cidr_blocks = [{ cidr_block = "10.0.0.0/8" display_name = "example_network" }], }]	list	<list>	no
monitoring_service	The monitoring service that the cluster should write metrics to. Automatically send metrics from pods in the cluster to the Google Cloud Monitoring API. VM metrics will be collected by Google Compute Engine regardless of this setting Available options include monitoring.googleapis.com, monitoring.googleapis.com/kubernetes (beta) and none	string	monitoring.googleapis.com	no
name	The name of the cluster (required)	string	-	yes
network	The VPC network to host the cluster in (required)	string	-	yes
network_policy	Enable network policy addon	string	false	no
network_project_id	The project ID of the shared VPC's host (for shared vpc support)	string	``	no
node_pools	List of maps containing node pools	list	<list>	no
node_pools_labels	Map of maps containing node labels by node-pool name	map	<map>	no
node_pools_tags	Map of lists containing node network tags by node-pool name	map	<map>	no
node_pools_taints	Map of lists containing node taints by node-pool name	map	<map>	no
node_version	The Kubernetes version of the node pools. Defaults kubernetes_version (master) variable and can be overridden for individual node pools by setting the version key on them. Must be empyty or set the same as master at cluster creation.	string	``	no
non_masquerade_cidrs	List of strings in CIDR notation that specify the IP address ranges that do not use IP masquerading.	list	<list>	no
project_id	The project ID to host the cluster in (required)	string	-	yes
region	The region to host the cluster in (required)	string	-	yes
regional	Whether is a regional cluster (zonal cluster if set false. WARNING: changing this after cluster creation is destructive!)	string	true	no
service_account	The service account to default running nodes as if not overridden in node_pools. Defaults to the compute engine default service account	string	``	no
stub_domains	Map of stub domains and their resolvers to forward DNS queries for a certain domain to an external DNS server	map	<map>	no
subnetwork	The subnetwork to host the cluster in (required)	string	-	yes
zones	The zones to host the cluster in (optional if regional cluster / required if zonal)	list	<list>	no

Outputs

Name	Description
ca_certificate	Cluster ca certificate (base64 encoded)
endpoint	Cluster endpoint
horizontal_pod_autoscaling_enabled	Whether horizontal pod autoscaling enabled
http_load_balancing_enabled	Whether http load balancing enabled
kubernetes_dashboard_enabled	Whether kubernetes dashboard enabled
location	Cluster location (region if regional cluster, zone if zonal cluster)
logging_service	Logging service used
master_authorized_networks_config	Networks from which access to master is permitted
master_version	Current master kubernetes version
min_master_version	Minimum master kubernetes version
monitoring_service	Monitoring service used
name	Cluster name
network_policy_enabled	Whether network policy enabled
node_pools_names	List of node pools names
node_pools_versions	List of node pools versions
region	Cluster region
type	Cluster type (regional / zonal)
zones	List of zones in which the cluster resides

Requirements

Before this module can be used on a project, you must ensure that the following pre-requisites are fulfilled:

1. Terraform and kubectl are installed on the machine where Terraform is executed.
2. The Service Account you execute the module with has the right permissions.
3. The Compute Engine and Kubernetes Engine APIs are active on the project you will launch the cluster in.
4. If you are using a Shared VPC, the APIs must also be activated on the Shared VPC host project and your service account needs the proper permissions there.

The project factory can be used to provision projects with the correct APIs active and the necessary Shared VPC connections.

Software Dependencies

Kubectl

• kubectl 1.9.x

Terraform plugins

• Terraform 0.10.x
• terraform-provider-google plugin v1.8.0

Configure a Service Account

In order to execute this module you must have a Service Account with the following project roles:

• roles/compute.viewer
• roles/container.clusterAdmin
• roles/container.developer
• roles/iam.serviceAccountUser

Enable APIs

In order to operate with the Service Account you must activate the following APIs on the project where the Service Account was created:

• Compute Engine API - compute.googleapis.com
• Kubernetes Engine API - container.googleapis.com

Install

Terraform

Be sure you have the correct Terraform version (0.10.x), you can choose the binary here:

• https://releases.hashicorp.com/terraform/

File structure

The project has the following folders and files:

• /: root folder
• /examples: examples for using this module
• /scripts: Scripts for specific tasks on module (see Infrastructure section on this file)
• /test: Folders with files for testing the module (see Testing section on this file)
• /main.tf: main file for this module, contains all the resources to create
• /variables.tf: all the variables for the module
• /output.tf: the outputs of the module
• /readme.MD: this file

Testing

Requirements

• bundler
• gcloud
• terraform-docs 0.3.0

Autogeneration of documentation from .tf files

Run

make generate_docs

Integration test

Integration tests are run though test-kitchen, kitchen-terraform, and InSpec.

Six test-kitchen instances are defined:

• deploy_service
• node_pool
• shared_vpc
• simple_regional
• simple_zonal
• stub_domains

The test-kitchen instances in test/fixtures/ wrap identically-named examples in the examples/ directory.

Setup

1. Configure the test fixtures
2. Download a Service Account key with the necessary permissions and put it in the module's root directory with the name credentials.json.
3. Build the Docker containers for testing:

CREDENTIALS_FILE="credentials.json" make docker_build_terraform
CREDENTIALS_FILE="credentials.json" make docker_build_kitchen_terraform

4. Run the testing container in interactive mode:

make docker_run

The module root directory will be loaded into the Docker container at /cftk/workdir/. 5. Run kitchen-terraform to test the infrastructure:

1. kitchen create creates Terraform state and downloads modules, if applicable.
2. kitchen converge creates the underlying resources. Run kitchen converge <INSTANCE_NAME> to create resources for a specific test case.
3. kitchen verify tests the created infrastructure. Run kitchen verify <INSTANCE_NAME> to run a specific test case.
4. kitchen destroy tears down the underlying resources created by kitchen converge. Run kitchen destroy <INSTANCE_NAME> to tear down resources for a specific test case.

Alternatively, you can simply run CREDENTIALS_FILE="credentials.json" make test_integration_docker to run all the test steps non-interactively.

Test configuration

Each test-kitchen instance is configured with a variables.tfvars file in the test fixture directory, e.g. test/fixtures/node_pool/terraform.tfvars. For convenience, since all of the variables are project-specific, these files have been symlinked to test/fixtures/shared/terraform.tfvars. Similarly, each test fixture has a variables.tf to define these variables, and an outputs.tf to facilitate providing necessary information for inspec to locate and query against created resources.

Each test-kitchen instance creates a GCP Network and Subnetwork fixture to house resources, and may create any other necessary fixture data as needed.

Autogeneration of documentation from .tf files

Run

make generate_docs

Linting

The makefile in this project will lint or sometimes just format any shell, Python, golang, Terraform, or Dockerfiles. The linters will only be run if the makefile finds files with the appropriate file extension.

All of the linter checks are in the default make target, so you just have to run

make -s

The -s is for 'silent'. Successful output looks like this

Running shellcheck
Running flake8
Running go fmt and go vet
Running terraform validate
Running hadolint on Dockerfiles
Checking for required files
Testing the validity of the header check
..
----------------------------------------------------------------------
Ran 2 tests in 0.026s

OK
Checking file headers
The following lines have trailing whitespace

The linters are as follows:

• Shell - shellcheck. Can be found in homebrew
• Python - flake8. Can be installed with 'pip install flake8'
• Golang - gofmt. gofmt comes with the standard golang installation. golang is a compiled language so there is no standard linter.
• Terraform - terraform has a built-in linter in the 'terraform validate' command.
• Dockerfiles - hadolint. Can be found in homebrew