Metakgp:SysAdmin/2019-10-13 Managing DNS records using Terraform

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Terraform setup[edit source]

What is Terraform?[edit source]

Terraform is a software package which powers the management of infrastructure using text configuration files which can be edited by multiple people.

Terraform Terminology[edit source]

  • Resource: This is a part of the infrastructure that we are managing through terraform. Eg: A DNS record, a domain name, an AWS S3 bucket
  • State: Terraform stores what it thinks the current state of the infrastructure is in a .tfstate file. This file is used to print the plan whenever one wants to change the infrastructure in some way. This file is a JSON file which can be inspected as a text file as well.
  • Backend: This is the location used to store the terraform state file. Changes to the state file must be persisted such that after a given apply operation, the new state file is used to calculate the next plan.

Operations[edit source]

There are two operations that terraform can perform and these happen in sequence one after the other:

  1. terraform plan: Look at the suggested changes, compare them to the state file and print the resources that are going to change.
    Terraform will perform the following actions:
    + resource "cloudflare_record" "proxy2_siddharthkannan_in_a" {
      + created_on  = (known after apply)
      + hostname    = (known after apply)
      + id          = (known after apply)
      + metadata    = (known after apply)
      + modified_on = (known after apply)
      + name        = "proxy2"
      + proxiable   = (known after apply)
      + proxied     = false
      + ttl         = 1
      + type        = "A"
      + value       = ""
      + zone_id     = "12f2bfc8884886a6701201e2a87da61a"
    Plan: 1 to add, 0 to change, 0 to destroy.
  2. terraform apply: Apply the changes shown in the previous plan operation.

    $ terraform apply -input=false $PLAN
    cloudflare_record.proxy2_siddharthkannan_in_a: Creating...
    cloudflare_record.proxy2_siddharthkannan_in_a: Creation complete after 0s [id=5604ae8289b7a61b955c2ae4b449fe2d]