Terraform Search and Bulk Import

Discover existing cloud resources using declarative queries and generate configuration for bulk import into Terraform state.

References:

• Terraform Search - list block
• Bulk Import

When to Use

• Bringing unmanaged resources under Terraform control
• Auditing existing cloud infrastructure
• Migrating from manual provisioning to IaC
• Discovering resources across multiple regions/accounts

IMPORTANT: Check Provider Support First

BEFORE starting, you MUST verify the target resource type is supported:

# Check what list resources are available
./scripts/list_resources.sh aws      # Specific provider
./scripts/list_resources.sh          # All configured providers

Decision Tree

1. Identify target resource type (e.g., aws_s3_bucket, aws_instance)

2. Check if supported: Run ./scripts/list_resources.sh <provider>

3. Choose workflow:

   • ** If supported**: Check for terraform version available.
   • ** If terraform version is above 1.14.0** Use Terraform Search workflow (below)
   • ** If not supported or terraform version is below 1.14.0 **: Use Manual Discovery workflow (see references/MANUAL-IMPORT.md)

   Note: The list of supported resources is rapidly expanding. Always verify current support before using manual import.

Prerequisites

Before writing queries, verify the provider supports list resources for your target resource type.

Discover Available List Resources

Run the helper script to extract supported list resources from your provider:

# From a directory with provider configuration (runs terraform init if needed)
./scripts/list_resources.sh aws      # Specific provider
./scripts/list_resources.sh          # All configured providers

Or manually query the provider schema:

terraform providers schema -json | jq '.provider_schemas | to_entries | map({key: (.key | split("/")[-1]), value: (.value.list_resource_schemas // {} | keys)})'

Terraform Search requires an initialized working directory. Ensure you have a configuration with the required provider before running queries:

# terraform.tf
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 6.0"
    }
  }
}

Run terraform init to download the provider, then proceed with queries.

Terraform Search Workflow (Supported Resources Only)

1. Create .tfquery.hcl files with list blocks defining search queries
2. Run terraform query to discover matching resources
3. Generate configuration with -generate-config-out=<file>
4. Review and refine generated resource and import blocks
5. Run terraform plan and terraform apply to import

Query File Structure

Query files use .tfquery.hcl extension and support:

• provider blocks for authentication
• list blocks for resource discovery
• variable and locals blocks for parameterization

# discovery.tfquery.hcl
provider "aws" {
  region = "us-west-2"
}

list "aws_instance" "all" {
  provider = aws
}

List Block Syntax

list "<list_type>" "<symbolic_name>" {
  provider = <provider_reference>  # Required

  # Optional: filter configuration (provider-specific)
  # The `config` block schema is provider-specific. Discover available options using `terraform providers schema -json | jq '.provider_schemas."registry.terraform.io/hashicorp/<provider>".list_resource_schemas."<resource_type>"'`

  config {
    filter {
      name   = "<filter_name>"
      values = ["<value1>", "<value2>"]
    }
    region = "<region>"  # AWS-specific
  }
  # Optional: limit results
  limit = 100
}

Supported List Resources

Provider support for list resources varies by version. Always check what's available for your specific provider version using the discovery script.

Query Examples

Basic Discovery

# Find all EC2 instances in configured region
list "aws_instance" "all" {
  provider = aws
}

Filtered Discovery

# Find instances by tag
list "aws_instance" "production" {
  provider = aws
  
  config {
    filter {
      name   = "tag:Environment"
      values = ["production"]
    }
  }
}

# Find instances by type
list "aws_instance" "large" {
  provider = aws
  
  config {
    filter {
      name   = "instance-type"
      values = ["t3.large", "t3.xlarge"]
    }
  }
}

Multi-Region Discovery

provider "aws" {
  region = "us-west-2"
}

locals {
  regions = ["us-west-2", "us-east-1", "eu-west-1"]
}

list "aws_instance" "all_regions" {
  for_each = toset(local.regions)
  provider = aws
  
  config {
    region = each.value
  }
}

Parameterized Queries

variable "target_environment" {
  type    = string
  default = "staging"
}

list "aws_instance" "by_env" {
  provider = aws
  
  config {
    filter {
      name   = "tag:Environment"
      values = [var.target_environment]
    }
  }
}

Running Queries

# Execute queries and display results
terraform query

# Generate configuration file
terraform query -generate-config-out=imported.tf

# Pass variables
terraform query -var='target_environment=production'

Query Output Format

list.aws_instance.all   account_id=123456789012,id=i-0abc123,region=us-west-2   web-server

Columns: <query_address> <identity_attributes> <name_tag>

Generated Configuration

The -generate-config-out flag creates:

# __generated__ by Terraform
resource "aws_instance" "all_0" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t2.micro"
  # ... all attributes
}

import {
  to       = aws_instance.all_0
  provider = aws
  identity = {
    account_id = "123456789012"
    id         = "i-0abc123"
    region     = "us-west-2"
  }
}

Post-Generation Cleanup

Generated configuration includes all attributes. Clean up by:

1. Remove computed/read-only attributes
2. Replace hardcoded values with variables
3. Add proper resource naming
4. Organize into appropriate files

# Before: generated
resource "aws_instance" "all_0" {
  ami                    = "ami-0c55b159cbfafe1f0"
  instance_type          = "t2.micro"
  arn                    = "arn:aws:ec2:..."  # Remove - computed
  id                     = "i-0abc123"        # Remove - computed
  # ... many more attributes
}

# After: cleaned
resource "aws_instance" "web_server" {
  ami           = var.ami_id
  instance_type = var.instance_type
  subnet_id     = var.subnet_id
  
  tags = {
    Name        = "web-server"
    Environment = var.environment
  }
}

Import by Identity

Generated imports use identity-based import (Terraform 1.12+):

import {
  to       = aws_instance.web
  provider = aws
  identity = {
    account_id = "123456789012"
    id         = "i-0abc123"
    region     = "us-west-2"
  }
}

Best Practices

Query Design

• Start broad, then add filters to narrow results
• Use limit to prevent overwhelming output
• Test queries before generating configuration

Configuration Management

• Review all generated code before applying
• Remove unnecessary default values
• Use consistent naming conventions
• Add proper variable abstraction

Troubleshooting

Complete Example

# main.tf - Initialize provider
terraform {
  required_version = ">= 1.14"
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 6.0"  # Always use latest version
    }
  }
}

# discovery.tfquery.hcl - Define queries
provider "aws" {
  region = "us-west-2"
}

list "aws_instance" "team_instances" {
  provider = aws
  
  config {
    filter {
      name   = "tag:Owner"
      values = ["platform"]
    }
    filter {
      name   = "instance-state-name"
      values = ["running"]
    }
  }
  
  limit = 50
}

# Execute workflow
terraform init
terraform query
terraform query -generate-config-out=generated.tf
# Review and clean generated.tf
terraform plan
terraform apply