This is Part-03 of Developer's Guide to Terraform in this section we are going to discuss about the Terraform Commands.
As we know that terraform is command line tool like git, Kubernetes, this means that terraform also gets operated with its command line like we operate git or Kubernetes with command line.
Terraform also offers various commands which you can use... to know the list of command name you can use terraform help command
🦄 terraform -h
Usage: terraform [global options] <subcommand> [args]
The available commands for execution are listed below.
The primary workflow commands are given first, followed by
less common or more advanced commands.
Main commands:
init Prepare your working directory for other commands
validate Check whether the configuration is valid
plan Show changes required by the current configuration
apply Create or update infrastructure
destroy Destroy previously-created infrastructure
All other commands:
console Try Terraform expressions at an interactive command prompt
fmt Reformat your configuration in the standard style
force-unlock Release a stuck lock on the current workspace
get Install or upgrade remote Terraform modules
graph Generate a Graphviz graph of the steps in an operation
import Associate existing infrastructure with a Terraform resource
login Obtain and save credentials for a remote host
logout Remove locally-stored credentials for a remote host
output Show output values from your root module
providers Show the providers required for this configuration
refresh Update the state to match remote systems
show Show the current state or a saved plan
state Advanced state management
taint Mark a resource instance as not fully functional
test Experimental support for module integration testing
untaint Remove the 'tainted' state from a resource instance
version Show the current Terraform version
workspace Workspace management
Global options (use these before the subcommand, if any):
-chdir=DIR Switch to a different working directory before executing the
given subcommand.
-help Show this help output, or the help for a specified subcommand.
-version An alias for the "version" subcommand.
With above result you can see that terraform has various commands which you can use to manage your infrastructure but to begin with terraform to automate your infrastructure you may not need to know all of these, in this blog we will discuss what all commands you need to know to provision Infrastructure with terraform.
Terraform Init
The terraform init command is used to initialize a working directory containing Terraform configuration files. This is the first command that should be run after writing a new Terraform configuration or cloning an existing one from version control. It is safe to run this command multiple times.
Usage
terraform init [options]
🦄 terraform init -h
Options:
-backend=false Disable backend or Terraform Cloud initialization for
this configuration and use what what was previously
initialized instead.
aliases: -cloud=false
-backend-config=path Configuration to be merged with what is in the
configuration file's 'backend' block. This can be
either a path to an HCL file with key/value
assignments (same format as terraform.tfvars) or a
'key=value' format, and can be specified multiple
times. The backend type must be in the configuration
itself.
-force-copy Suppress prompts about copying state data when
initializating a new state backend. This is
equivalent to providing a "yes" to all confirmation
prompts.
-from-module=SOURCE Copy the contents of the given module into the target
directory before initialization.
-get=false Disable downloading modules for this configuration.
-input=false Disable interactive prompts. Note that some actions may
require interactive prompts and will error if input is
disabled.
-lock=false Don't hold a state lock during backend migration.
This is dangerous if others might concurrently run
commands against the same workspace.
-lock-timeout=0s Duration to retry a state lock.
-no-color If specified, output won't contain any color.
-plugin-dir Directory containing plugin binaries. This overrides all
default search paths for plugins, and prevents the
automatic installation of plugins. This flag can be used
multiple times.
-reconfigure Reconfigure a backend, ignoring any saved
configuration.
-migrate-state Reconfigure a backend, and attempt to migrate any
existing state.
-upgrade Install the latest module and provider versions
allowed within configured constraints, overriding the
default behavior of selecting exactly the version
recorded in the dependency lockfile.
-lockfile=MODE Set a dependency lockfile mode.
Currently only "readonly" is valid.
-ignore-remote-version A rare option used for Terraform Cloud and the remote backend
only. Set this to ignore checking that the local and remote
Terraform versions use compatible state representations, making
an operation proceed even when there is a potential mismatch.
See the documentation on configuring Terraform with
Terraform Cloud for more information.
Let's look at various parameter option with terraform init command
1. Terraform init with backend
If you have terraform provider block with empty backend blocked specified like this
terraform {
required_providers {
azurerm = {
version = "~> 2.88.1"
source = "hashicorp/azurerm"
}
}
backend "azurerm" {
}
}
Then you need to specify the backend at the time of initialization of terraform from terraform init command, to do that you can run terraform init with backend-config option
terraform init -backend-config=storage_account_name=tfstatefile01 -backend-config=container_name=tfstate -backend-config=key=dev-network.terraform.tstate -backend-config=resource_group_name=DefaultResourceGroup-EUS -backend-config=subscription_id=2a04288a-8136-4880-b526-c6070e59f004 -backend-config=tenant_id=37d20c78-05e3-416d-83ab-cdbc21fed22a -backend-config=client_id=*** -backend-config=client_secret=***
As you can see terraform backend-config parameter multiple times.
Here with terraform init we are specifying following terraform backend configuration
- azure backend storage account name
- azure backend storage account resource group name
- azure backend storage account container name
- azure subscription Id
- azure tenant id
- azure service principal client Id
- azure service principal client secret
It is also possible that partial configuration you specify in terraform code block and partial with terraform init backend-config parameters.
| NOTE |
|---|
| If your terraform backend block is defined empty as given above then backend configuration must requires to specify at terraform init command otherwise it will throw an error |
🦄 terraform init
Initializing modules...
Initializing the backend...
container_name
The container name.
Enter a value:
key
The blob key.
Enter a value:
storage_account_name
The name of the storage account.
Enter a value:
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│ Error: obtaining Authorization Token from the Azure CLI: parsing json result from the Azure CLI: waiting for the Azure CLI: exit status 1: ERROR: AADSTS50173: The provided grant has expired due to it being revoked, a fresh auth token is needed. The user might have changed or reset their password. The grant was issued on '2022-07-28T06:34:30.5567960Z' and the TokensValidFrom date (before which tokens are not valid) for this user is '2022-08-16T19:33:00.0000000Z'.
2. Terraform Init without backend
Now let's say we have terraform provider defined with empty backend and we still would like to run terraform init command without terraform backend then you can do that with backend=false option.
Here is the command
terraform {
required_providers {
azurerm = {
version = "~> 2.88.1"
source = "hashicorp/azurerm"
}
}
backend "azurerm" {
}
}
🦄 terraform init -backend=false
Initializing modules...
Initializing provider plugins...
- Reusing previous version of hashicorp/azurerm from the dependency lock file
- Reusing previous version of aztfmod/azurecaf from the dependency lock file
- Using previously-installed hashicorp/azurerm v2.88.1
- Using previously-installed aztfmod/azurecaf v1.2.18
Terraform has been successfully initialized!
You may now begin working with Terraform. Try running "terraform plan" to see
any changes that are required for your infrastructure. All Terraform commands
should now work.
If you ever set or change modules or backend configuration for Terraform,
rerun this command to reinitialize your working directory. If you forget, other
commands will detect it and remind you to do so if necessary.
3. Disable Input action with Terraform Init
By default if you run terraform init it will ask for the backend configuration as prompt, if you want you can disable the prompt option using input=false option
| NOTE |
|---|
| Disabling interactive prompts give some error if input is disabled |
That's it for now, there are some other options also available with terraform init command which we can take at look at later in some other section.
Next we will look at terraform plan command.
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