inital pass at adding terraform for the k8s charms

charms/worker/k8s/terraform/README.md

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+# Terraform module for k8s
+
+This is a Terraform module facilitating the deployment of the k8s charm, using the [Terraform juju provider](https://github.com/juju/terraform-provider-juju/). For more information, refer to the provider [documentation](https://registry.terraform.io/providers/juju/juju/latest/docs).
+
+## Requirements
+This module requires a `juju` model to be available. Refer to the [usage section](#usage) below for more details.
+
+## API
+
+### Inputs
+The module offers the following configurable inputs:
+
+| Name | Type | Description | Required |
+| - | - | - | - |
+| `app_name`| string | Application name | False |
+| `channel`| string | Channel that the charm is deployed from | False |
+| `config`| map(string) | Map of the charm configuration options | False |
+| `constriants` | string | Juju constraits to apply for this aplication | False |
+| `model`| string | Name of the model that the charm is deployed on | True |
+| `resources`| map(string) | Map of the charm resources | False |
+| `revision`| number | Revision number of the charm name | False |
+| `series` | string | Ubuntu series to deploy the carm onto | False |
+| `units` | number | Number of units to deploy | False |
+
+### Outputs
+Upon applied, the module exports the following outputs:
+
+| Name | Description |
+| - | - |
+| `app_name`|  Application name |
+| `provides`| Map of `provides` endpoints |
+| `requires`|  Map of `requires` endpoints |
+
+## Usage
+
+This module is intended to be used as part of a higher-level module. When defining one, users should ensure that Terraform is aware of the `juju_model` dependency of the charm module. There are two options to do so when creating a high-level module:
+
+### Define a `juju_model` resource
+Define a `juju_model` resource and pass to the `model_name` input a reference to the `juju_model` resource's name. For example:
+
+```
+resource "juju_model" "testing" {
+  name = canonical-k8s
+}
+module "k8s" {
+  source = "<path-to-this-directory>"
+  model_name = juju_model.testing.name
+}
+```
+
+### Define a `data` source
+Define a `data` source and pass to the `model_name` input a reference to the `data.juju_model` resource's name. This will enable Terraform to look for a `juju_model` resource with a name attribute equal to the one provided, and apply only if this is present. Otherwise, it will fail before applying anything.
+```
+data "juju_model" "testing" {
+  name = var.model_name
+}
+module "k8s" {
+  source = "<path-to-this-directory>"
+  model_name = data.juju_model.testing.name
+}
+```

charms/worker/k8s/terraform/main.tf

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+# Copyright 2024 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+resource "juju_application" "k8s" {
+  name  = var.app_name
+  model = var.model
+
+  charm {
+    name     = "k8s"
+    channel  = var.channel
+    revision = var.revision
+    series   = var.series
+  }
+
+  config      = var.config
+  constraints = var.constraints
+  units       = var.units
+  resources   = var.resources
+}

charms/worker/k8s/terraform/outputs.tf

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+# Copyright 2024 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+output "app_name" {
+  description = "Name of the deployed application."
+  value       = juju_application.k8s.name
+}
+
+output "requires" {
+  value = {
+    aws         = "aws-integration"
+    azure       = "azure-integration"
+    cluster     = "k8s-cluster"
+    cos_tokens  = "cos-k8s-tokens"
+    containerd  = "containerd"
+    gcp         = "gcp-integration"
+  }
+}
+
+output "provides" {
+  value = {
+    cos_agent   = "cos_agent"
+  }
+}

charms/worker/k8s/terraform/variables.tf

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+# Copyright 2024 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+variable "app_name" {
+  description = "Name of the application in the Juju model."
+  type        = string
+  default     = "k8s"
+}
+
+variable "channel" {
+  description = "The channel to use when deploying a charm."
+  type        = string
+  default     = "1.30/edge"
+}
+
+variable "config" {
+  description = "Application config. Details about available options can be found at https://charmhub.io/k8s/configurations."
+  type        = map(string)
+  default     = {}
+}
+
+variable "constraints" {
+  description = "Juju constraints to apply for this application."
+  type        = string
+  default     = "arch=amd64"
+}
+
+variable "model" {
+  description = "Reference to a `juju_model`."
+  type        = string
+  default     = ""
+}
+
+variable "resources" {
+  description = "Resources to use with the application. Details about available options can be found at https://charmhub.io/k8s/configurations."
+  type        = map(string)
+  default     = {}
+}
+
+variable "revision" {
+  description = "Revision number of the charm"
+  type        = number
+  default     = null
+}
+
+variable "series" {
+  description = "Ubuntu series to deploy the charm onto"
+  type        = string
+  default     = "24.04"
+
+  validation {
+    condition     = contains(["20.04", "22.04", "24.04"], var.series)
+    error_message = "Series must be one of 20.04, 22.04, 24.04"
+  }
+}
+
+variable "units" {
+  description = "Number of units to deploy"
+  type        = number
+  default     = 1
+}

charms/worker/k8s/terraform/versions.tf

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+terraform {
+  required_version = ">= 1.6"
+  required_providers {
+    juju = {
+      source  = "juju/juju"
+      version = "~> 0.14.0"
+    }
+  }
+}

charms/worker/terraform/README.md

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+# Terraform module for k8s-worker
+
+This is a Terraform module facilitating the deployment of the k8s-worker charm, using the [Terraform juju provider](https://github.com/juju/terraform-provider-juju/). For more information, refer to the provider [documentation](https://registry.terraform.io/providers/juju/juju/latest/docs).
+
+## Requirements
+This module requires a `juju` model to be available. Refer to the [usage section](#usage) below for more details.
+
+## API
+
+### Inputs
+The module offers the following configurable inputs:
+
+| Name | Type | Description | Required |
+| - | - | - | - |
+| `app_name`| string | Application name | False |
+| `channel`| string | Channel that the charm is deployed from | False |
+| `config`| map(string) | Map of the charm configuration options | False |
+| `constriants` | string | Juju constraits to apply for this aplication | False |
+| `model`| string | Name of the model that the charm is deployed on | True |
+| `resources`| map(string) | Map of the charm resources | False |
+| `revision`| number | Revision number of the charm name | False |
+| `series` | string | Ubuntu series to deploy the carm onto | False |
+| `units` | number | Number of units to deploy | False |
+
+### Outputs
+Upon applied, the module exports the following outputs:
+
+| Name | Description |
+| - | - |
+| `app_name`|  Application name |
+| `provides`| Map of `provides` endpoints |
+| `requires`|  Map of `requires` endpoints |
+
+## Usage
+
+This module is intended to be used as part of a higher-level module. When defining one, users should ensure that Terraform is aware of the `juju_model` dependency of the charm module. There are two options to do so when creating a high-level module:
+
+### Define a `juju_model` resource
+Define a `juju_model` resource and pass to the `model_name` input a reference to the `juju_model` resource's name. For example:
+
+```
+resource "juju_model" "testing" {
+  name = canonical-k8s
+}
+module "k8s_worker" {
+  source = "<path-to-this-directory>"
+  model_name = juju_model.testing.name
+}
+```
+
+### Define a `data` source
+Define a `data` source and pass to the `model_name` input a reference to the `data.juju_model` resource's name. This will enable Terraform to look for a `juju_model` resource with a name attribute equal to the one provided, and apply only if this is present. Otherwise, it will fail before applying anything.
+```
+data "juju_model" "testing" {
+  name = var.model_name
+}
+module "k8s_worker" {
+  source = "<path-to-this-directory>"
+  model_name = data.juju_model.testing.name
+}
+```

charms/worker/terraform/main.tf

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+# Copyright 2024 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+resource "juju_application" "k8s_worker" {
+  name  = var.app_name
+  model = var.model
+
+  charm {
+    name     = "k8s-worker"
+    channel  = var.channel
+    revision = var.revision
+    series   = var.series
+  }
+
+  config      = var.config
+  constraints = var.constraints
+  units       = var.units
+  resources   = var.resources
+}

charms/worker/terraform/outputs.tf

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+# Copyright 2024 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+output "app_name" {
+  description = "Name of the deployed application."
+  value       = juju_application.k8s_worker.name
+}
+
+output "requires" {
+  value = {
+    aws         = "aws-integration"
+    azure       = "azure-integration"
+    cluster     = "k8s-cluster"
+    cos_tokens  = "cos-k8s-tokens"
+    containerd  = "containerd"
+    gcp         = "gcp-integration"
+  }
+}
+
+output "provides" {
+  value = {
+    cos_agent   = "cos_agent"
+  }
+}

charms/worker/terraform/variables.tf

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+# Copyright 2024 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+variable "app_name" {
+  description = "Name of the application in the Juju model."
+  type        = string
+  default     = "k8s-worker"
+}
+
+variable "channel" {
+  description = "The channel to use when deploying a charm."
+  type        = string
+  default     = "1.30/edge"
+}
+
+variable "config" {
+  description = "Application config. Details about available options can be found at https://charmhub.io/k8s-worker/configurations."
+  type        = map(string)
+  default     = {}
+}
+
+variable "constraints" {
+  description = "Juju constraints to apply for this application."
+  type        = string
+  default     = "arch=amd64"
+}
+
+variable "model" {
+  description = "Reference to a `juju_model`."
+  type        = string
+  default     = ""
+}
+
+variable "resources" {
+  description = "Resources to use with the application. Details about available options can be found at https://charmhub.io/k8s-worker/configurations."
+  type        = map(string)
+  default     = {}
+}
+
+variable "revision" {
+  description = "Revision number of the charm"
+  type        = number
+  default     = null
+}
+
+variable "series" {
+  description = "Ubuntu series to deploy the charm onto"
+  type        = string
+  default     = "24.04"
+
+  validation {
+    condition     = contains(["20.04", "22.04", "24.04"], var.series)
+    error_message = "Series must be one of 20.04, 22.04, 24.04"
+  }
+}
+
+variable "units" {
+  description = "Number of units to deploy"
+  type        = number
+  default     = 1
+}

charms/worker/terraform/versions.tf

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+terraform {
+  required_version = ">= 1.6"
+  required_providers {
+    juju = {
+      source  = "juju/juju"
+      version = "~> 0.14.0"
+    }
+  }
+}