The newbie cloud architect diary

• (Free) Terraform CLI is the core application available for Mac, Linux, Windows, FreeBSD and Solaris.
• (Free) Terraform Providers are infrastructure specific plugins that connect to Iaas/PaaS, ex. AWS
• (Commercial) Terraform Cloud is the paid platform that includes:
• either access to the managed service or the self-hosted distribution called "Terraform Enterprise"
• developer collaboration (registry)
• workflow orchestration (control plane)
• support

• HCL/HIL support available as Jetbrain Intellij/PyCharm plugin and Microsoft VSCode extension
• Terragrunt is an open-source thin wrapper for Terraform CLI that provides extra tools for keeping your configurations DRY, working with multiple Terraform modules, and managing remote state.
• Kubestack is an open-source framework that builds on top of Terraform for DevOps teams that want to implement GitOps as their operational model.
• Terraform visual is an open-source lean editor for Terraform configuration
• Codeherent is a general purpose visual development platform which integrates with Terraform

• Data source is the input of a configuration, ex. HTTP
• Resource is the molecular object ex. AWS Security group, Subnet etc.
• Resource module is the atomic asset or collection of connected resources ex. AWS VPC
• Infrastrcuture module is the grouping object or collection of resource modules
• Infrastructrure composition is the combining object or collection of infrastructure modules

• Day 1
• init: Download providers required by all .tf files of current path (1 directory = 1 composition)
• plan: Define execution setps to reach the desired state (-out for persisting)
• apply [dir-or-plan]: Provision infrastructure as per configuration directory or execution plan
• Day n+
• refresh: Compare control view with the real-world
• plan
• apply
• destroy: Decommission infrastructure as per the rollback plan
• Optional
• version: List currently used client + plugins and version
• validate: Verify configuration syntax
  
• fmt: Make configuration format pretty
• graph: Generate a graph definition in Graphviz dot format
• providers: List currently used providers and versions
• state list: List managed configurations
  
• output: Extract output values from current state

$ mkdir tf-docker & cd tf-docker
$ cat << EOF > variables.tf
variable "nginx_version" {
  default = "1.7.8"
}
EOF

$ cat << EOF > main.tf 
# provider with remote API enabled
provider "docker" {
  host = "http://127.0.0.1:2375"
}

# image resource
resource "docker_image" "nginx" {
  name         = "nginx:${var.nginx_version}"
  keep_locally = false
}

# container resource
resource "docker_container" "nginx" {
  image = "${docker_image.nginx.latest}"
  name  = "tutorial"
  ports {
    internal = 80
    external = 8000
  }
}

EOF

$ terraform init
$ terraform -v
Terraform v0.11.11
+ provider.docker

$ terraform graph > main.dot
$ dotty main.dot  

$ mkdir tf-aws & cd tf-aws
$ cat << EOF > main.tf 
provider "aws" {
  profile = "default"
  region  = "us-east-1"
}
resource "aws_instance" "example" {
  ami           = "ami-2757f631"
  instance_type = "t2.micro"
}
output "instance_ip_addr" {
  value       = "${aws_instance.example.*.public_ip}"
  description = "Pulic IP address of the AWS EC2 instance."
}
EOF

$ mkdir tf-k8s & cd tf-k8s
$ cat << EOF > main.tf
resource "kubernetes_deployment" "example" {
  metadata {
    name = "terraform-example"
    labels = {
      test = "MyExampleApp"
    }
  }

  spec {
    replicas = 1

    selector {
      match_labels = {
        test = "MyExampleApp"
      }
    }

    template {
      metadata {
        labels = {
          test = "MyExampleApp"
        }
      }

      spec {
        container {
          image = "nginx:1.7.8"
          name  = "example"
        }
      }
    }
  }
}
EOF

$ terraform init
$ terraform -v
Terraform v0.11.11
+ provider.kubernetes
$ terraform plan
$ terraform apply -auto-approve
Apply complete! Resources: 1 added, 0 changed, 0 destroyed.

$ kubectl get pods
NAME                                 READY   STATUS    RESTARTS   AGE
terraform-example-7877b6cf45-nl2q5   1/1     Running   0          26s
$ terraform destroy  -auto-approve
Apply complete! Resources: 0 added, 0 changed, 1 destroyed.

$ kubectl get pods
NAME                                 READY   STATUS    RESTARTS   AGE