Kubernetes Terraform Provider

The k8s Terraform provider enables Terraform to deploy Kubernetes resources. Unlike the official Kubernetes provider it handles raw manifests, leveraging controller-runtime and the Unstructured API directly to allow developers to work with any Kubernetes resource natively.

This project is a hard fork of ericchiang/terraform-provider-k8s.

Installation

The Go Get way

Use go get to install the provider:

go get -u github.com/banzaicloud/terraform-provider-k8s

Register the plugin in ~/.terraformrc (see Documentation for Windows users):

providers {
  k8s = "/$GOPATH/bin/terraform-provider-k8s"
}

The Terraform Plugin way (enable versioning)

Download a release from the Release page and make sure the name matches the following convention:

OS	Version	Name
LINUX	0.4.0	terraform-provider-k8s_v0.4.0
	0.3.0	terraform-provider-k8s_v0.3.0
Windows	0.4.0	terraform-provider-k8s_v0.4.0.exe
	0.3.0	terraform-provider-k8s_v0.3.0.exe

Install the plugin using Terraform Third-party Plugin Documentation:

Operating system	User plugins directory
Windows	%APPDATA%\terraform.d\plugins
All other systems	~/.terraform.d/plugins

Usage

The provider uses your default Kubernetes configuration by default, but it takes some optional configuration parameters, see the Configuration section (these parameters are the same as for the Kubernetes provider).

provider "k8s" {
  config_context = "prod-cluster"
}

The k8s Terraform provider introduces a single Terraform resource, a k8s_manifest. The resource contains a content field, which contains a raw manifest.

variable "replicas" {
  type    = "string"
  default = 3
}

data "template_file" "nginx-deployment" {
  template = "${file("manifests/nginx-deployment.yaml")}"

  vars {
    replicas = "${var.replicas}"
  }
}

resource "k8s_manifest" "nginx-deployment" {
  content = "${data.template_file.nginx-deployment.rendered}"
}

# creating a second resource in the nginx namespace
resource "k8s_manifest" "nginx-deployment" {
  content   = "${data.template_file.nginx-deployment.rendered}"
  namespace = "nginx"
}

In this case manifests/nginx-deployment.yaml is a templated deployment manifest.

apiVersion: apps/v1beta2
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: ${replicas}
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.9
        ports:
        - containerPort: 80

The Kubernetes resources can then be managed through Terraform.

$ terraform apply
# ...
Apply complete! Resources: 1 added, 1 changed, 0 destroyed.
$ kubectl get deployments
NAME               DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   3         3         3            3           1m
$ terraform apply -var 'replicas=5'
# ...
Apply complete! Resources: 0 added, 1 changed, 0 destroyed.
$ kubectl get deployments
NAME               DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   5         5         5            3           3m
$ terraform destroy -force
# ...
Destroy complete! Resources: 2 destroyed.
$ kubectl get deployments
No resources found.

Helm workflow

Requirements

• Helm 2 or Helm 3

Get a versioned chart into your source code and render it

Helm 2

helm fetch stable/nginx-ingress --version 1.24.4 --untardir charts --untar
helm template --namespace nginx-ingress .\charts\nginx-ingress --output-dir manifests/

Helm 3

helm pull stable/nginx-ingress --version 1.24.4 --untardir charts --untar
helm template --namespace nginx-ingress nginx-ingress .\charts\nginx-ingress --output-dir manifests/

Apply the main.tf with the k8s provider

# terraform 0.12.x
locals {
  nginx-ingress_files   = fileset(path.module, "manifests/nginx-ingress/templates/*.yaml")
}

data "local_file" "nginx-ingress_files_content" {
  for_each = local.nginx-ingress_files
  filename = each.value
}

resource "k8s_manifest" "nginx-ingress" {
  for_each = data.local_file.nginx-ingress_files_content
  content  = each.value.content
  namespace = "nginx"
}

Configuration

There are generally two ways to configure the Kubernetes provider.

File config

The provider always first tries to load a config file from a given (or default) location. Depending on whether you have current context set this may require config_context_auth_info and/or config_context_cluster and/or config_context.

Setting default config context

Here's an example for how to set default context and avoid all provider configuration:

kubectl config set-context default-system \
  --cluster=chosen-cluster \
  --user=chosen-user

kubectl config use-context default-system

Read more about kubectl in the official docs.

In-cluster service account token

If no other configuration is specified, and when it detects it is running in a kubernetes pod, the provider will try to use the service account token from the /var/run/secrets/kubernetes.io/serviceaccount/token path. Detection of in-cluster execution is based on the sole availability both of the KUBERNETES_SERVICE_HOST and KUBERNETES_SERVICE_PORT environment variables, with non empty values.

provider "k8s" {
  load_config_file = "false"
}

If you have any other static configuration setting specifiedin a config file or static configuration, in-cluster service account token will not be tried.

Statically defined credentials

An other way is statically define TLS certificate credentials:

provider "k8s" {
  load_config_file = "false"

  host = "https://104.196.242.174"

  client_certificate     = "${file("~/.kube/client-cert.pem")}"
  client_key             = "${file("~/.kube/client-key.pem")}"
  cluster_ca_certificate = "${file("~/.kube/cluster-ca-cert.pem")}"
}

or username and password (HTTP Basic Authorization):

provider "k8s" {
  load_config_file = "false"

  host = "https://104.196.242.174"

  username = "username"
  password = "password"
}

If you have both valid configuration in a config file and static configuration, the static one is used as override. i.e. any static field will override its counterpart loaded from the config.

Argument Reference

The following arguments are supported:

• host - (Optional) The hostname (in form of URI) of Kubernetes master. Can be sourced from KUBE_HOST.
• username - (Optional) The username to use for HTTP basic authentication when accessing the Kubernetes master endpoint. Can be sourced from KUBE_USER.
• password - (Optional) The password to use for HTTP basic authentication when accessing the Kubernetes master endpoint. Can be sourced from KUBE_PASSWORD.
• insecure - (Optional) Whether server should be accessed without verifying the TLS certificate. Can be sourced from KUBE_INSECURE. Defaults to false.
• client_certificate - (Optional) PEM-encoded client certificate for TLS authentication. Can be sourced from KUBE_CLIENT_CERT_DATA.
• client_key - (Optional) PEM-encoded client certificate key for TLS authentication. Can be sourced from KUBE_CLIENT_KEY_DATA.
• cluster_ca_certificate - (Optional) PEM-encoded root certificates bundle for TLS authentication. Can be sourced from KUBE_CLUSTER_CA_CERT_DATA.
• config_path - (Optional) Path to the kube config file. Can be sourced from KUBE_CONFIG or KUBECONFIG. Defaults to ~/.kube/config.
• config_context - (Optional) Context to choose from the config file. Can be sourced from KUBE_CTX.
• config_context_auth_info - (Optional) Authentication info context of the kube config (name of the kubeconfig user, --user flag in kubectl). Can be sourced from KUBE_CTX_AUTH_INFO.
• config_context_cluster - (Optional) Cluster context of the kube config (name of the kubeconfig cluster, --cluster flag in kubectl). Can be sourced from KUBE_CTX_CLUSTER.
• token - (Optional) Token of your service account. Can be sourced from KUBE_TOKEN.
• load_config_file - (Optional) By default the local config (~/.kube/config) is loaded when you use this provider. This option at false disables this behaviour which is desired when statically specifying the configuration or relying on in-cluster config. Can be sourced from KUBE_LOAD_CONFIG_FILE.
• exec - (Optional) Configuration block to use an [exec-based credential plugin] (https://kubernetes.io/docs/reference/access-authn-authz/authentication/#client-go-credential-plugins), e.g. call an external command to receive user credentials.
  • api_version - (Required) API version to use when decoding the ExecCredentials resource, e.g. client.authentication.k8s.io/v1beta1.
  • command - (Required) Command to execute.
  • args - (Optional) List of arguments to pass when executing the plugin.
  • env - (Optional) Map of environment variables to set when executing the plugin.