Add terraform module (#350)

1. Working terraform apply
2. Requires and provides integrations in outputs 

---------

Signed-off-by: Michael Thamm <[email protected]>
Co-authored-by: Leon <[email protected]>

.github/workflows/pull-request.yaml

@@ -12,3 +12,7 @@ jobs:
     secrets: inherit
     with:
       ip-range: 10.64.140.43/30
+
+  terraform-checks:
+    name: Terraform
+    uses: canonical/observability/.github/workflows/terraform-quality-checks.yaml@main

.gitignore

@@ -9,3 +9,39 @@ venv
 tests/integration/grafana-tester/lib/charms/grafana_k8s/*
 cos-tool*
 sqlite-static
+
+# Local .terraform directories
+**/.terraform/*
+
+# .tfstate files
+*.tfstate
+*.tfstate.*
+
+# Crash log files
+crash.log
+crash.*.log
+
+# Exclude all .tfvars files, which are likely to contain sensitive data, such as
+# password, private keys, and other secrets. These should not be part of version 
+# control as they are data points which are potentially sensitive and subject 
+# to change depending on the environment.
+*.tfvars
+*.tfvars.json
+
+# Ignore override files as they are usually used to override resources locally and so
+# are not checked in
+override.tf
+override.tf.json
+*_override.tf
+*_override.tf.json
+
+# Include override files you do wish to add to version control using negated pattern
+# !example_override.tf
+
+# Include tfplan files to ignore the plan output of command: terraform plan -out=tfplan
+# example: *tfplan*
+
+# Ignore CLI configuration files
+.terraformrc
+terraform.rc
+.terraform.lock.hcl

terraform/README.md

@@ -0,0 +1,4 @@
+# Terraform module for grafana-k8s
+
+
+This module is in experimental status. It is not yet ready for production.

terraform/main.tf

@@ -0,0 +1,12 @@
+resource "juju_application" "grafana" {
+  name  = var.app_name
+  model = var.model_name
+  trust = true
+  charm {
+    name     = "grafana-k8s"
+    channel  = var.channel
+    revision = var.revision
+  }
+  units  = var.units
+  config = var.config
+}

terraform/outputs.tf

@@ -0,0 +1,24 @@
+output "app_name" {
+  value = juju_application.grafana.name
+}
+
+output "requires" {
+  value = {
+    catalogue         = "catalogue",
+    certificates      = "certificates",
+    database          = "database",
+    grafana_auth      = "grafana-auth",
+    grafana_dashboard = "grafana-dashboard",
+    grafana_source    = "grafana-source",
+    ingress           = "ingress",
+    oauth             = "oauth",
+    receive_ca_cert   = "receive-ca-cert",
+    tracing           = "tracing",
+  }
+}
+
+output "provides" {
+  value = {
+    metrics_endpoint = "metrics-endpoint",
+  }
+}

terraform/variables.tf

@@ -0,0 +1,42 @@
+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?u=jose
+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 = "~> 0.14"
+    }
+  }
+}