From a9efc5cd455ec36cb0ddedb83cabd1a436baf2fd Mon Sep 17 00:00:00 2001
From: "Jason C. Nucciarone" <nuccitheboss@ubuntu.com>
Date: Fri, 22 Nov 2024 13:48:25 -0500
Subject: [PATCH] feat: add module to deploy and integrate grafana agent with
 slurmctld

Changes:

* Replace `juju_applicaton` entry for `mysql` with the
  tf module from the upstream `mysql-operator` GitHub repository.

Signed-off-by: Jason C. Nucciarone <nuccitheboss@ubuntu.com>
---
 main.tf      | 64 ++++++++++++++++++++++++++++++++++++----------------
 variables.tf | 12 +++++-----
 2 files changed, 50 insertions(+), 26 deletions(-)

diff --git a/main.tf b/main.tf
index 372ed21..9f06888 100644
--- a/main.tf
+++ b/main.tf
@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# Deploy a minimal Charmed HPC cloud on LXD
+## Deploy a Charmed HPC cluster.
 
 provider "juju" {}
 
@@ -20,6 +20,7 @@ resource "juju_model" "charmed-hpc" {
   name = var.model
 }
 
+## Slurm - workload manager for Charmed HPC.
 module "controller" {
   source = "git::https://github.com/charmed-hpc/slurm-charms//charms/slurmctld/terraform"
 
@@ -56,21 +57,19 @@ module "rest-api" {
   units      = var.rest-api-scale
 }
 
-# FIXME: Source from upstream mysql operator once tf module is published.
-resource "juju_application" "mysql" {
-  name  = "mysql"
-  model = juju_model.charmed-hpc.name
-
-  charm {
-    name     = "mysql"
-    channel  = var.mysql-channel
-    revision = var.mysql-revision
-  }
+## MySQL - provides backing database for `slurmdbd`.
+module "mysql" {
+  source = "git::https://github.com/canonical/mysql-operator//terraform"
 
-  units = var.mysql-scale
+  juju_model_name = juju_model.charmed-hpc.name
+  app_name        = "mysql"
+  channel         = var.mysql-channel
+  units           = var.mysql-scale
 }
 
-# FIXME: Source from upstream mysql-router operator once tf module is published.
+# TODO:
+#   Pull a Terraform module for mysql-router-operator once
+#   it has been published to the upstream repository.
 resource "juju_application" "database-mysql-router" {
   name  = "database-mysql-router"
   model = juju_model.charmed-hpc.name
@@ -80,9 +79,20 @@ resource "juju_application" "database-mysql-router" {
     channel  = var.mysql-router-channel
     revision = var.mysql-router-revision
   }
-  units = 0
+  units = 0 # Units should always be zero since mysql-router is a subordinate operator.
 }
 
+## Grafana Agent - forwards collected cluster metrics to COS.
+module "grafana-agent" {
+  source = "git::https://github.com/canonical/grafana-agent-operator//terraform"
+
+  model_name = juju_model.charmed-hpc.name
+  app_name   = "grafana-agent"
+  channel    = var.grafana-agent-channel
+  units      = 0 # Units should always be zero since grafana-agent is a subordinate operator.
+}
+
+## Integrate `slurmctld`, `slurmd`, `slurmdbd`, and `slurmrestd` together.
 resource "juju_integration" "compute-to-controller" {
   model = juju_model.charmed-hpc.name
 
@@ -125,30 +135,44 @@ resource "juju_integration" "rest-api-to-controller" {
   }
 }
 
+## Integrate `slurmd` with `mysql`.
 resource "juju_integration" "database-to-mysql-router" {
   model = juju_model.charmed-hpc.name
 
   application {
-    name     = module.database.app_name
-    endpoint = module.database.requires.database
+    name     = juju_application.database-mysql-router.name
+    endpoint = "database"
   }
 
   application {
-    name     = juju_application.database-mysql-router.name
-    endpoint = "database"
+    name     = module.database.app_name
+    endpoint = module.database.requires.database
   }
 }
 
 resource "juju_integration" "mysql-router-to-mysql" {
   model = juju_model.charmed-hpc.name
 
+  application {
+    name     = module.mysql.application_name
+    endpoint = module.mysql.provides.database
+  }
+
   application {
     name     = juju_application.database-mysql-router.name
     endpoint = "backend-database"
   }
+}
+
+## Integrate `slurmctld` with `grafana-agent`.
+resource "juju_integration" "controller-to-grafana-agent" {
+  model = juju_model.charmed-hpc.name
 
   application {
-    name     = juju_application.mysql.name
-    endpoint = "database"
+    name = module.controller.app_name
+  }
+
+  application {
+    name = module.grafana-agent.app_name
   }
 }
diff --git a/variables.tf b/variables.tf
index f4510ee..cb47ab4 100644
--- a/variables.tf
+++ b/variables.tf
@@ -54,18 +54,18 @@ variable "database-scale" {
   default     = 1
 }
 
+variable "grafana-agent-channel" {
+  description = "Channel to deploy grafana-agent-operator from."
+  type        = string
+  default     = "latest/stable"
+}
+
 variable "mysql-channel" {
   description = "Channel to deploy mysql from."
   type        = string
   default     = "8.0/stable"
 }
 
-variable "mysql-revision" {
-  description = "Revision of mysql to deploy from channel."
-  type        = number
-  default     = null
-}
-
 variable "mysql-scale" {
   description = "Scale of mysql application"
   type        = number