> ## Documentation Index
> Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Demo HCL Basics
> This article covers HCL basics using OpenTofu, including resource types, initialization, and applying changes to local file resources.
In this hands-on lesson, you’ll explore HashiCorp Configuration Language (HCL) fundamentals using OpenTofu. You’ll identify resource types and names, initialize your working directory, and apply changes to a local file resource.
***
## Q1: Identify the HCL File Extension
Navigate to your HCL project directory and list its contents:
```bash theme={null}
cd ~/opentofu-projects/HCL/
ls
# → main.tf
```
Alternatively, open the folder in VS Code and observe that the filename is `main.tf`.\
**Answer:** `.tf`
***
## Q2: Determine the Resource Type
Inspect the resource block in `main.tf`:
```hcl theme={null}
resource "local_file" "games" {
file = "/root/favorite-games"
content = "FIFA 21"
}
```
**Answer:** `local_file`
***
## Q3: Find the Resource Name
Within the same block, the second quoted identifier denotes the resource name:
```hcl theme={null}
resource "local_file" "games" { … }
```
**Answer:** `games`
***
## Q4: Identify the Provider Name
The provider is indicated by the prefix of the resource type:
```hcl theme={null}
resource "local_file" "games" { … }
```
Here, **local** is the provider.\
**Answer:** `local`
***
## Q5: Valid vs. Invalid Arguments
The `local_file` resource supports only `filename` and `content`. It does *not* accept `resource_type`.
| Argument | Valid | Description |
| -------------- | :---: | --------------------------------- |
| filename | Yes | Path to create the file |
| content | Yes | Data to write into the file |
| resource\_type | No | Not a supported resource argument |
**Answer:** `resource_type = "local_file"`
***
## Q6: Why `tofu plan` Fails Initially
Running:
```bash theme={null}
tofu plan
```
Produces:
```plaintext theme={null}
Error: Inconsistent dependency lock file
… no version is selected
```
The directory must be initialized first.
Always run `tofu init` before planning or applying any changes.
***
### Initialize the Working Directory
```bash theme={null}
tofu init
```
You should see:
```plaintext theme={null}
OpenTofu has been successfully initialized!
…
```
***
## Q7: Locate the Provider Plugin Version
After initialization, OpenTofu downloads provider plugins. You can confirm the version (`2.5.1`) from the output or by inspecting `.terraform`:
**Answer:** `2.5.1`
***
## Q8: Re-run `tofu plan` with Incorrect Arguments
```bash theme={null}
tofu plan
```
Results in:
```plaintext theme={null}
Error: Missing required argument
on main.tf line 1, in resource "local_file" "games":
1: resource "local_file" "games" {
The argument "filename" is required, but no definition was found.
Error: Unsupported argument
on main.tf line 2, in resource "local_file" "games":
2: file = "/root/favorite-games"
An argument named "file" is not expected here.
```
You used `file` instead of `filename` and omitted `filename`.
***
## Q9: Identify the Unsupported Argument
Referring to the [Local Provider Documentation](https://registry.opentofu.dev/hashicorp/local/latest/docs/resources/file), `file` is not supported.\
**Answer:** `file`
***
## Q10: Correct the Configuration and Apply
Update **main.tf**:
```hcl theme={null}
resource "local_file" "games" {
filename = "/root/favorite-games"
content = "FIFA 21"
}
```
Run:
```bash theme={null}
tofu plan
tofu apply
# → Apply complete! Resources: 1 added, 0 changed, 0 destroyed.
```
***
## Q11: Switch to a Sensitive File Resource
To mask content in plans, use `local_sensitive_file`:
```hcl theme={null}
resource "local_sensitive_file" "games" {
filename = "/root/favorite-games"
content = "FIFA 21"
}
```
Attempting to add an unsupported `sensitive_content` argument will fail:
```bash theme={null}
tofu plan
```
```plaintext theme={null}
Error: Unsupported argument
on main.tf line 4, in resource "local_sensitive_file" "games":
4: sensitive_content = "FIFA 21"
```
Remove `sensitive_content`; it’s not supported.
***
## Q12: Apply the Sensitive File Resource
With **main.tf** updated:
```hcl theme={null}
resource "local_sensitive_file" "games" {
filename = "/root/favorite-games"
content = "FIFA 21"
}
```
Run:
```bash theme={null}
tofu plan
tofu apply
# → Apply complete! Resources: 1 added, 0 changed, 1 destroyed.
```
Plans will now hide the file’s content.
***
## Q13: Destroy the Resource
```bash theme={null}
tofu destroy
```
```plaintext theme={null}
Plan: 0 to add, 0 to change, 1 to destroy.
Enter a value: yes
Destroy complete! Resources: 1 destroyed.
```
Congratulations—you’ve completed the lab! 🎉
***
## Links and References
* [OpenTofu Documentation](https://opentofu.dev/docs/)
* [Local Provider (OpenTofu)](https://registry.opentofu.dev/hashicorp/local)
* [HCL Language Overview](https://github.com/hashicorp/hcl)