first implementation of terraform module (#200)

* first implementation of terraform module

* add terraform lines in .gitignore

.gitignore

@@ -8,3 +8,13 @@ __pycache__/
 .idea/
 tests/integration/*-tester/lib/
 .env
+
+# Terraform
+*.tfstate
+*.tfstate.*
+*.tfplan
+.terraform.lock.hcl
+crash.log
+.terraform/
+terraform.tfvars
+terraform.tfvars.json

terraform/README.md

@@ -0,0 +1,37 @@
+# Terraform module for grafana-agent
+
+
+This is a Terraform module facilitating the deployment of grafana-agent 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 | mimir-worker |
+| `channel`| string | Channel that the charm is deployed from | latest/edge |
+| `config`| map(any) | Map of the charm configuration options | {} |
+| `constraints`| string | Constraints for the Juju deployment| "" |
+| `model_name`| string | Name of the model that the charm is deployed on |  |
+| `revision`| number | Revision number of the charm name | null |
+| `units`| number | Number of units to deploy | 1 |
+
+### Outputs
+Upon applied, the module exports the following outputs:
+
+| Name | Description |
+| - | - |
+| `app_name`|  Application name |
+| `requires`|  Map of `requires` endpoints |
+
+## Usage
+
+Users should ensure that Terraform is aware of the `juju_model` dependency of the charm module.
+
+To deploy this module with its needed dependency, you can run `terraform apply -var="model_name=<MODEL_NAME>" -auto-approve`

terraform/main.tf

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+resource "juju_application" "grafana_agent" {
+  name = var.app_name
+  model = var.model_name
+  trust = true # We always need this variable to be true in order to be able to apply resources limits. 
+
+  charm {
+    name     = "grafana-agent"
+    channel  = var.channel
+    revision = var.revision
+  }
+  units  = var.units
+  config = var.config
+}

terraform/outputs.tf

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+output "app_name" {
+  value = juju_application.grafana_agent.name
+}

terraform/variables.tf

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+variable "app_name" {
+  description = "Application name"
+  type        = string
+}
+
+variable "channel" {
+  description = "Charm channel"
+  type        = string
+  default     = "latest/stable"
+}
+
+variable "config" {
+  description = "Config options as in the ones we pass in juju config"
+  type        = map(string)
+  default     = {}
+}
+
+# We use constraints to set AntiAffinity in K8s
+# https://discourse.charmhub.io/t/pod-priority-and-affinity-in-juju-charms/4091/13
+variable "constraints" {
+  description = "Constraints to be applied"
+  type        = string
+  default     = ""
+}
+
+variable "model_name" {
+  description = "Model name"
+  type        = string
+}
+
+variable "revision" {
+  description = "Charm revision"
+  type        = number
+  nullable    = true
+  default     = null
+}
+
+variable "units" {
+  description = "Number of units"
+  type        = number
+  default     = 1
+}

terraform/versions.tf

@@ -0,0 +1,9 @@
+terraform {
+  required_version = ">= 1.5"
+  required_providers {
+    juju = {
+      source  = "juju/juju"
+      version = "~> 0.15.0"
+    }
+  }
+}