oddu-terraform-introduction

This repository is meant for a general/basic introduction to Terraform

Prerequisites

Included is an mdp specific markdown file (oddu_terraform.md) for the presentation. In order to view this in "presentation" style, you will need the mdp tool.
- Once installed, you can simply mdp oddu_terraform.md to see the file in presentation mode.
In order to try out Terraform you will need to download it. The demo uses v0.12.24 which can be found in the GitHub releases.
You will need an actual "playground" to actually build any infrastructure.
There are some HashiCorp provided examples that provide some good information / outlining of the usage of variables, userdata scripts, outputs, etc. I would strongly encourage glancing through a few of the provided examples (will still require an AWS "playground" with proper permissions in order to actually do any planning/applying).

Formatting

There is a small example file format_me.tf included for practice with terraform fmt. It has a range of spacing for the configurations, but one can use terraform fmt within this directory to adjust the spacing automatically to a cleaner, better format.

Example Workflow

(Example captured from devops github repository)

User writes a new .tf file to add a Jenkins target group to existing application load balancer

resource "aws_lb_target_group" "jenkins-alb-tg" {
  name        = "dsva-vagov-utility-jenkins-lb-tg"
  port        = 80
  protocol    = "HTTP"
  target_type = "ip"
  vpc_id      = aws_vpc.vpc.id
}

resource "aws_alb_target_group_attachment" "jenkins-vetsgov" {
  target_group_arn  = aws_lb_target_group.jenkins-alb-tg.arn
  target_id         = "172.31.1.100"
  availability_zone = "all"
}

resource "aws_lb_listener_rule" "jenkins-http" {
  listener_arn = module.internal-tools-alb.listener-http-arn
  priority     = 1

  action {
    type             = "forward"
    target_group_arn = aws_lb_target_group.jenkins-alb-tg.arn
  }

  condition {
    host_header {
      values = ["jenkins.vfs.va.gov"]
    }
  }
}

User runs terraform fmt in order to catch any spacing errors / cleanup the code
User runs terraform init to initialize the directory, install any specified provider plugins, etc.
User runs terraform plan to see the proposed changes to the infrastructure

------------------------------------------------------------------------

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  # aws_alb_target_group_attachment.jenkins-vetsgov will be created
  + resource "aws_alb_target_group_attachment" "jenkins-vetsgov" {
      + id               = (known after apply)
      + target_group_arn = (known after apply)
      + target_id        = "172.31.1.100"
    }

  # aws_lb_listener_rule.jenkins-http will be created
  + resource "aws_lb_listener_rule" "jenkins-http" {
      + arn          = (known after apply)
      + id           = (known after apply)
      + listener_arn = "arn:aws-us-gov:elasticloadbalancing:us-gov-west-1:008577686731:listener/app/dsva-vagov-utility-tools/30a7782e04179703/d50903741669dca4"
      + priority     = 1

      + action {
          + order            = (known after apply)
          + target_group_arn = (known after apply)
          + type             = "forward"
        }

      + condition {
          + field  = (known after apply)
          + values = (known after apply)

          + host_header {
              + values = [
                  + "jenkins.vfs.va.gov",
                ]
            }

          + path_pattern {
              + values = (known after apply)
            }
        }
    }

  # aws_lb_target_group.jenkins-alb-tg will be created
  + resource "aws_lb_target_group" "jenkins-alb-tg" {
      + arn                                = (known after apply)
      + arn_suffix                         = (known after apply)
      + deregistration_delay               = 300
      + id                                 = (known after apply)
      + lambda_multi_value_headers_enabled = false
      + name                               = "dsva-vagov-utility-jenkins-lb-tg"
      + port                               = 80
      + protocol                           = "HTTP"
      + proxy_protocol_v2                  = false
      + slow_start                         = 0
      + target_type                        = "ip"
      + vpc_id                             = "vpc-84a444e0"

      + health_check {
          + enabled             = (known after apply)
          + healthy_threshold   = (known after apply)
          + interval            = (known after apply)
          + matcher             = (known after apply)
          + path                = (known after apply)
          + port                = (known after apply)
          + protocol            = (known after apply)
          + timeout             = (known after apply)
          + unhealthy_threshold = (known after apply)
        }

      + stickiness {
          + cookie_duration = (known after apply)
          + enabled         = (known after apply)
          + type            = (known after apply)
        }
    }

Plan: 3 to add, 0 to change, 0 to destroy.

------------------------------------------------------------------------

User reviews intended changes and ensures that there are no surprises / discrepancies for the apply step
If all looks good from the plan, user runs terraform apply
This will again output the intended changes and prompt the user to type "yes" or "no" to accept/decline the changes
If user enters "yes" at the prompt, Terraform will then apply all proposed changes

oddballteam/oddu-terraform-introduction

oddu-terraform-introduction

Prerequisites

Formatting

Example Workflow