Terraform Core Commands
This page is work in progress
Thanks
Richard
30th November 2018
Terraform commands
–help is help
Tab completion enabled by terraform -install-autocomplete
| Command | What it does? |
|---|---|
| terraform -install-autocomplete | Enables tab completion |
| -help | Shows the help files |
| apply | apply the changes |
| console | creates and interactive console |
| destroy | destroys the Terraform-managed infrastructure |
| fmt | used to rewrite Terraform configuration files |
| force-unlock | used to remove lock on the state for the current configuration |
| get | used to download and update modules |
| graph | used to generate a a graph |
| import | used to import existing resources |
| init | used to initilize a working directory |
| output | used to extract the value of an output variable |
| plan | used to create an execution plan |
| providers | used to print information about providers (eg VMware, AWS, HyperV etc etc etc) |
| push | used to upload your configuration |
| refresh | used to update the state of a file |
| show | useds to provide output from a state or plan file |
| state | used for advanced state management |
| taint | used to mark resources as tainted |
| validate | used to validate the syntax of terraform files |
| untaint | used to unmark a resourse as tainted |
| workspace | used to manage workspaces |
Subcommands
| Command | What it does |
|---|---|
| list | used to list all existing workspaces |
| select | used to choose different workspaces |
| new | used to create a new workspace |
| delete | used to delete and existing workspace |
Terraform Syntax
The syntax of Terraform configurations is called HashiCorp Configuration Language (HCL). It is meant to strike a balance between human readable and editable as well as being machine-friendly. For machine-friendliness, Terraform can also read JSON configurations
HCL Syntax (HashiCorp Configuration Language)
Here is an example of HashiCorp Configuration Language (HCL)
# An AMI
variable “ami” {
description = “the AMI to use”
}
/* A multi
line comment. */
resource “aws_instance” “web” {
ami = “${var.ami}”
count = 2
source_dest_check = false
connection {
user = “root”
}
} Source: https://www.terraform.io/docs/configuration/syntax.html
JSON Syntax
Terraform also supports JSON which is a machine friendly language
{
“variable”: {
“ami”: {
“description”: “the AMI to use”
}
},
“resource”: {
“aws_instance”: {
“web”: {
“ami”: “${var.ami}”,
“count”: 2,
“source_dest_check”: false,
“connection”: {
“user”: “root”
}
}
}
}
} Source: https://www.terraform.io/docs/configuration/syntax.html
Variables
| Type or Variable | What it does |
|---|---|
| "var" prefix | User String Variable Interpolate |
| "var.MAP["KEY"] | User Map Variable Value of Key |
| "${var.LIST}" | Value of the list as a list List elements by Index |
| "self.ATTRIBUTE" | Own Resource |
| "TYPE.NAME.ATTRIBUTE" | Other Resource |
| "data.TYPE.NAME.ATTRIBUTE" | Data Source |
| MODULE.NAME.OUTPUT" | Module outputs |
| "Count.FIELD" | Count |
| "path.TYPE" | Path |
| "terraform.FIELD" | Terraform Meta |
