Terraform Module

module block: 2. Module block

1. Overview:

• A module:
  • A container for multiple resources that are used together
  • A collections of .tf and/or .tf.json in a directory
    • Each must defines a distinct set of config objects
    • Not in nested directory
• The root module:
  • A Terraform config has atleast 1 module which is the root module
  • Contains all .tf files in the working directory
• Child module:
  • A Terraform module can call other modules to include their resources in the configuration
• Published modules:
  • Terraform can load modules from public (Terraform Registry) or private registry
• Using modules:
  • By using 2. Module block
  • Or 3. Module sources
  • or 4. Module meta-arguments
    • with providers, depends on, count, for each

2. Module block:

• Calling a child module:
  • To cal a module means to include the contents of that module into the configuration with specific values for its Input variables

  • module "<LABEL>" {
       <module-specific-inputs>
       source = "<location-of-module-sources>"
       version = "<constraint>" # only available for modules listed in a registry
       count = <number> # mutually exclusive with `for_each`
       for_each = {          # mutually exclusive with `count`
           <KEY> = <VALUE>
        }
        for_each = [       # `for_each` accepts a map or a set of strings
         "<VALUE>",
         "<VALUE>"
        ]
       provider = "<alias.provider-configuration>"
       depends_on = [ <resource.address.reference> ]

  } ```
  • This block is called the calling module of the child module
    • The label right after is the local-name
  • Module call use arguments:
    • source:
      • mandatory
      • value is:
        • the path to a local directory containing the module’s configuration files
        • or a remote module source that Terraform should download and use
      • 3. Module sources
    • version:
      • recommended
      • Can use 13. Version constraints
    • 4. Module meta-arguments

3. Module sources:

• local path
• registry:
  • source = "<NAMESPACE>/<NAME>/<PROVIDER>"
  • for HCP terraform private registry: source = "app.terraform.io/<NAMESPACE>/<NAME>/<PROVIDER>"
  • For Terraform enterprise: source = "<HOSTNAME>/<NAMESPACE>/<NAME>/<PROVIDER>"
  • For Github over https: source = "github.com/<ORGANIZATION>/<MODULE-FOLDER>"
  • For github over ssh: source = "git:github.com/<ORGANIZATION>/<MODULE-FOLDER>"

4. Module meta-arguments:

• s

5. Module development: