---
title: Vet a Terraform provider offline
sidebarTitle: Terraform
description: Download a provider once, then validate and plan without network access
icon: "cubes"
---

<Tooltip tip="This workflow prepares and restores a local disk snapshot, which is not available on microsandbox cloud."><span className="msb-badge-local">Local-only <Icon icon="circle-info" size={11} /></span></Tooltip>

Terraform providers are native executables. Prepare the provider in one microVM, snapshot it, then run validation and planning in a fresh networkless worker.

The `random` provider makes the flow easy to test because planning it does not need cloud credentials.

## Run an offline plan

<Steps>

<Step title="Create a test configuration">

```hcl main.tf
terraform {
  required_providers {
    random = {
      source  = "hashicorp/random"
      version = "3.7.2"
    }
  }
}

resource "random_pet" "example" {
  prefix = "microsandbox"
}
```

</Step>

<Step title="Download and snapshot the provider">

<CodeGroup>
```sh macOS & Linux
msb run --name terraform-base --replace \
  --memory 768M --root-disk 2G --max-duration 5m \
  --copy-file ./main.tf:/workspace/main.tf \
  --workdir /workspace \
  --entrypoint sh \
  hashicorp/terraform:1.13.5 -- -lc \
    'terraform init -backend=false -input=false && chown -R 65534:65534 /workspace'
```

```powershell Windows
msb run --name terraform-base --replace `
  --memory 768M --root-disk 2G --max-duration 5m `
  --copy-file ./main.tf:/workspace/main.tf `
  --workdir /workspace `
  --entrypoint sh `
  hashicorp/terraform:1.13.5 -- -lc `
    'terraform init -backend=false -input=false && chown -R 65534:65534 /workspace'
```
</CodeGroup>

Copy the generated dependency lock file to the host:

```sh
msb cp terraform-base:/workspace/.terraform.lock.hcl ./.terraform.lock.hcl
```

Capture the downloaded provider:

<CodeGroup>
```sh macOS & Linux
msb snapshot create terraform-runtime \
  --from terraform-base --integrity --force
```

```powershell Windows
msb snapshot create terraform-runtime `
  --from terraform-base --integrity --force
```
</CodeGroup>

Verify the snapshot before using it:

```sh
msb snapshot verify terraform-runtime
```

`terraform init` downloads the provider and creates `.terraform.lock.hcl`. The copy on the host is ready to review and commit when adapting this to a real module.

</Step>

<Step title="Plan offline">

<CodeGroup>
```sh macOS & Linux
msb run --name terraform-vet --replace \
  --from-snapshot terraform-runtime \
  --workdir /workspace --user 65534:65534 \
  --env HOME=/tmp \
  --cpus 1 --memory 512M --max-duration 1m \
  --no-net --security restricted \
  --entrypoint sh -- -lc \
    'terraform fmt -check && terraform validate && terraform plan -refresh=false -input=false -lock=false'
```

```powershell Windows
msb run --name terraform-vet --replace `
  --from-snapshot terraform-runtime `
  --workdir /workspace --user 65534:65534 `
  --env HOME=/tmp `
  --cpus 1 --memory 512M --max-duration 1m `
  --no-net --security restricted `
  --entrypoint sh -- -lc `
    'terraform fmt -check && terraform validate && terraform plan -refresh=false -input=false -lock=false'
```
</CodeGroup>

The provider loads and creates a plan, but it cannot contact any remote API. Providers, data sources, or validation rules that require a service will fail offline; that failure is the point of this vetting mode.

<Warning>
  `-refresh=false` is not a network boundary. `--no-net` is. If you give a provider credentials and egress, changes it makes through an external API outlive the microVM.
</Warning>

</Step>

<Step title="Clean up">

```sh
msb rm -f terraform-base terraform-vet
```

Remove the reusable snapshot:

```sh
msb snapshot remove terraform-runtime
```

</Step>

</Steps>

## Reference

- [How Terraform works with plugins](https://developer.hashicorp.com/terraform/plugin/how-terraform-works)
- [Provider dependency lock file](https://developer.hashicorp.com/terraform/language/files/dependency-lock)