HashiCorp Configuration Language (HCL)

HCL is a declarative configuration language developed by HashiCorp where .tf is its well known file extension. It is mainly used in HashiCorp products such as #HashiCorp Terraform. It is one of the good example of domain language. The general syntax is looked like below:

resource "local_file" "my_file" {
  content = "Hello World"
  filename = "/root/hello_world"
}

The above example specify a resource block with parameters of local_file and my_file. Defined within the block scope is what will be passed as arguments to the according resource plugin#. Generally speaking, the block will contain the information about the infrastructure platform and resources from that infrastructure platform.

Links to this page

Terraform Variable

Variable can be defined in a variable block in #HashiCorp Configuration Language (HCL) for #HashiCorp Terraform in the file variables.tf. A comprehensive definition for a variable block should look like the following:
Terraform Resource Replication

Within #Terraform Providers, we can define a resource in such a way we could replicate multiple instances of them under different name. A recommended way to do this is by using a Terraform Meta Arguments# for_each. for_each will store a list of values, of type# set or map, into a variable called each.value. The following shows the configuration# example:
Terraform Providers

We can use the resources brought by the providers by specifying the requirements in a configuration file# like below:

We could put a constraint on the Provider’s version used for the current project. Normally, in the Terraform Registry#, they will provide the configuration# to use the chosen version after pressing the “Use Provider” button. It could look like the following:
Terraform Plugins

#HashiCorp Terraform stores plugins under the local directory (the one where configuration files# located) .terraform/plugins/. Terraform will download any missing plugins for the infrastructure after calling terraform init.
Terraform Meta Arguments

Meta Arguments is a group of arguments in HashiCorp Configuration Language (HCL) that could alter a resource’s behaviour. It includes:
Terraform Data Source

#HashiCorp Terraform could provision other resources that are managed by other Infrastructure as Code (IaC) tools or manual maintenance using Data Sources. However, it doesn’t have any permission other than reading the infrastructure in contrast to Terraform Providers. It can be defined in HashiCorp Configuration Language (HCL)# as follows:
Infrastructure as Code (IaC)

IaC is a process to set up a development or production environment (infrastructure) which includes servers, databases, applications etc. declaratively by using languages such as YAML and HashiCorp Configuration Language (HCL). We can imagine it as the tool could use the blueprint to automatically construct a house without manual labour to do so.
HashiCorp Terraform

Terraform uses HashiCorp Configuration Language (HCL)# as its configuration language and utilises its declarative nature to set up infrastructure accordingly.

#declarative #configuration