How to deploy using Terraform

Terraform is an infrastructure automation tool to provision and manage resources in clouds or data centers. To deploy Charmed MySQL using Terraform and Juju, you can use the Juju Terraform Provider.

The easiest way is to start from these examples of terraform modules prepared by Canonical. This page will guide you through a deployment using an example module for MySQL on machines.

For an in-depth introduction to the Juju Terraform Provider, read this Discourse post.

Summary

• Install Terraform tooling
• Verify the deployment
• Apply the deployment
• Check deployment status
• Clean up

Install Terraform tooling

This guide assumes Juju is installed and you have an LXD controller already bootstrapped. For more information, check the Set up the environment tutorial page.

Let’s install Terraform Provider and example modules:

sudo snap install terraform --classic

Switch to the LXD provider and create a new model:

juju switch lxd
juju add-model my-model

Clone examples and navigate to the MySQL machine module:

git clone https://github.com/canonical/terraform-modules.git
cd terraform-modules/modules/machine/mysql

Initialise the Juju Terraform Provider:

terraform init

Verify the deployment

Open the main.tf file to see the brief contents of the Terraform module:

resource "juju_application" "machine_mysql" {
  name  = var.mysql_application_name
  model = var.juju_model_name
  trust = true

  charm {
    name    = "mysql"
    channel = var.mysql_charm_channel
  }

  units = 1
}

Run terraform plan to get a preview of the changes that will be made:

terraform plan -var "juju_model_name=my-model"

Apply the deployment

If everything looks correct, deploy the resources (skip the approval):

terraform apply -auto-approve -var "juju_model_name=my-model"

Check deployment status

Check the deployment status with

juju status --model lxd:my-model --watch 1s

Sample output:

Model     Controller      Cloud/Region         Version  SLA          Timestamp     
my-model  lxd-controller  localhost/localhost  3.5.3    unsupported  12:49:34Z     

App    Version          Status  Scale  Charm  Channel     Rev  Exposed  Message                                
mysql  8.0.36-0ubun...  active      1  mysql  8.0/stable  240  no                                   

Unit      Workload  Agent  Machine  Public address  Ports           Message    
mysql/0*  active    idle   0        10.101.248.225  3306,33060/tcp  Primary                           

Machine  State    Address         Inst id        Base          AZ  Message
0        started  10.101.248.225  juju-c4a403-0  [email protected]      Running   

Continue to operate the charm as usual from here or apply further Terraform changes.

Clean up

To keep the house clean, remove the newly deployed Charmed PostgreSQL by running

terraform destroy -var "juju_model_name=my-model"

Sample output:

juju_application.machine_mysql: Refreshing state... [id=my-model:mysql]

Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
  - destroy

Terraform will perform the following actions:

  # juju_application.machine_mysql will be destroyed
  - resource "juju_application" "machine_mysql" {
      - constraints = "arch=amd64" -> null
      - id          = "my-model:mysql" -> null
      - model       = "my-model" -> null
      - name        = "mysql" -> null
      - placement   = "0" -> null
      - storage     = [
          - {
              - count = 1 -> null
              - label = "database" -> null
              - pool  = "rootfs" -> null
              - size  = "99G" -> null
            },
        ] -> null
      - trust       = true -> null
      - units       = 1 -> null

      - charm {
          - base     = "[email protected]" -> null
          - channel  = "8.0/stable" -> null
          - name     = "mysql" -> null
          - revision = 240 -> null
          - series   = "jammy" -> null
        }
    }

Plan: 0 to add, 0 to change, 1 to destroy.

Changes to Outputs:
  - application_name = "mysql" -> null

Do you really want to destroy all resources?
  Terraform will destroy all your managed infrastructure, as shown above.
  There is no undo. Only 'yes' will be accepted to confirm.

  Enter a value: yes

juju_application.machine_mysql: Destroying... [id=my-model:mysql]
juju_application.machine_mysql: Destruction complete after 0s

Destroy complete! Resources: 1 destroyed.

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