kiranjthomas / terraform-config-inspect

A helper library for shallow inspection of Terraform configurations

terraform-config-inspect

This repository contains a helper library for extracting high-level metadata about Terraform modules from their source code. It processes only a subset of the information Terraform itself would process, and in return it's able to be broadly compatible with modules written for many different versions of Terraform.

$ go get github.com/hashicorp/terraform-config-inspect

import "github.com/hashicorp/terraform-config-inspect/tfconfig"

/// ...

    module, diags := tfconfig.LoadModule(dir)
    /// ...

There are not yet any formal compatibility promises for the Terraform configuration file format, so this tool can't yet promise to be compatible with unknown future extensions to the format. However, it should be capable of parsing valid configurations targeting Terraform versions between 0.10 and 0.12.

Command Line Tool

The primary way to use this repository is as a Go library, but as a convenience it also contains a CLI tool called terraform-config-inspect, installed automatically by the go get command above, that allows viewing module information in either a Markdown-like format or in JSON format.

$ terraform-config-inspect path/to/module

# Module `path/to/module`

Provider Requirements:
* **null:** (any version)

## Input Variables
* `a` (default `"a default"`)
* `b` (required): The b variable

## Output Values
* `a`
* `b`: I am B

## Managed Resources
* `null_resource.a` from `null`
* `null_resource.b` from `null`

$ terraform-config-inspect --json path/to/module
{
  "path": "path/to/module",
  "variables": {
    "A": {
      "name": "A",
      "default": "A default",
      "pos": {
        "filename": "path/to/module/basics.tf",
        "line": 1
      }
    },
    "B": {
      "name": "B",
      "description": "The B variable",
      "pos": {
        "filename": "path/to/module/basics.tf",
        "line": 5
      }
    }
  },
  "outputs": {
    "A": {
      "name": "A",
      "pos": {
        "filename": "path/to/module/basics.tf",
        "line": 9
      }
    },
    "B": {
      "name": "B",
      "description": "I am B",
      "pos": {
        "filename": "path/to/module/basics.tf",
        "line": 13
      }
    }
  },
  "required_providers": {
    "null": []
  },
  "managed_resources": {
    "null_resource.A": {
      "mode": "managed",
      "type": "null_resource",
      "name": "A",
      "provider": {
        "name": "null"
      },
      "pos": {
        "filename": "path/to/module/basics.tf",
        "line": 18
      }
    },
    "null_resource.B": {
      "mode": "managed",
      "type": "null_resource",
      "name": "B",
      "provider": {
        "name": "null"
      },
      "pos": {
        "filename": "path/to/module/basics.tf",
        "line": 19
      }
    }
  },
  "data_resources": {},
  "module_calls": {}
}

Contributing

This library and tool are intentionally focused on only extracting simple top-level metadata about a single Terraform module. This is to reduce the maintenance burden of keeping this codebase synchronized with changes to Terraform itself: the features extracted by this package are unlikely to change significantly in future versions.

For that reason, we cannot accept external PRs for this codebase that add support for additional Terraform language features.

We would be happy to review PRs to fix bugs in existing functionality or to improve the usability of the Go package API, however. We will be hesitant about any breaking changes to the API, since this library is used by a number of existing tools and systems.

To work on this codebase you will need a recent version of Go installed. Please ensure all files match the formatting rules applied by go fmt and that all unit tests are passing.