Explanation
Terraform configurations must declare which providers they require, so that Terraform can install and use
them.
Reference: https://www.terraform.io/docs/language/providers/configuration.html

Reference: https://www.terraform.io/docs/language/values/outputs.html

Explanation
The terraform validate command is used to validate the syntax of the terraform files. Terraform performs a
syntax check on all the terraform files in the directory, and will display an error if any of the files doesn't
validate. This command does not check formatting (e.g. tabs vs spaces, newlines, comments etc.). The
following can be reported: invalid HCL syntax (e.g. missing trailing quote or equal sign) invalid HCL
references (e.g. variable name or attribute which doesn't exist) same provider declared multiple times same
module declared multiple times same resource declared multiple times invalid module name interpolation used
in places where it's unsupported (e.g. variable, depends_on, module.source, provider) missing value for a
variable (none of -var foo=... flag, -var-file=foo.vars flag, TF_VAR_foo environment variable,
terraform.tfvars, or default value in the configuration)
https://www.typeerror.org/docs/terraform/commands/validate
https://learning-ocean.com/tutorials/terraform/terraform-validate