stratospire / terraform-google-iam

This Terraform module makes it easier to non-destructively manage multiple IAM roles for resources on Google Cloud Platform.

Google IAM Terraform Module

This Terraform module makes it easier to non-destructively manage multiple IAM roles for resources on Google Cloud Platform.

Usage

Full examples are in the examples folder, but basic usage is as follows for managing roles on two projects:

module "iam_binding" {
  source = "github.com/terraform-google-modules/terraform-google-iam?ref=v1.0.0"

  projects = ["project-123456", "project-9876543"]

  bindings = {
    "roles/storage.admin" = [
      "group:[email protected]",
      "user:[email protected]",
    ]

    "roles/compute.networkAdmin" = [
      "group:[email protected]",
      "user:[email protected]",
    ]

    "roles/compute.imageUser" = [
      "user:[email protected]",
    ]
  }
}

The module also offers an authoritative mode which will remove all roles not assigned through Terraform. This is an example of using the authoritative mode to manage access to a storage bucket:

module "storage_buckets_iam_binding" {
  source          = "github.com/terraform-google-modules/terraform-google-iam"
  storage_buckets = ["my-storage-bucket"]

  mode = "authoritative"

  bindings = {
    "roles/storage.legacyBucketReader" = [
      "user:[email protected]",
      "group:[email protected]",
    ]

    "roles/storage.legacyBucketWriter" = [
      "user:[email protected]",
      "group:[email protected]",
    ]
  }
}

Variables

Following variables are the most important to control module's behavior:

• Mode

  This variable controls the module's behavior, by default is set to "additive", possible options are:

  - additive: add members to role, old members are not deleted from this role.
  - authoritative: set the role's members, other roles' members are not deleted.
  

• Bindings

  Is a map of role (key) and list of members (value) with member type prefix, for example:

    ```hcl
    bindings = {
        "roles/<some_role>" = [
            "user:[email protected]",
            "group:[email protected]"
        ]
    }
    ```
  

• Project

  This variable can be defined either on provider section and the module calling itself. It is only used for the following resources:

  • service_accounts
  • pubsub_topics
  • pubsub_subscriptions

Please see the variables.tf file on root folder for more information about types and default values for module's variables.

Outputs

There is no outputs for this module.

Caveats

Referencing values/attributes from other resources

This Terraform module performs operations over some variables before making any changes on the IAM bindings in GCP.

Because of that, it is important to note that putting a value or attribute of a resource within the following variables, will cause an error:

• bindings
• projects
• organizations
• folders
• service_accounts
• subnets
• storage_buckets
• pubsub_topics
• pubsub_subscriptions
• kms_key_rings
• kms_crypto_keys

For example, this will fail:

resource google_folder "my_new_folder" {
  display_name = "folder-test"
  parent = "76543265432"
}

resource "google_service_account" "my_service_account" {
  account_id   = "my-new-service-account"
}

module "iam_binding" {
  source = "github.com/terraform-google-modules/terraform-google-iam"
  mode   = "authoritative"

  folders = ["${google_folder.my_new_folder.id}"]

  bindings = {
    "roles/storage.admin" = [
      "group:[email protected]",
      "serviceAccount:${google_service_account.my_service_account.id}",
    ]

    "roles/compute.networkAdmin" = [
      "group:[email protected]",
      "user:[email protected]",
    ]
  }
}

First, because the folders variable has a reference to a resource that is not already created (my_new_folder). Second because the bindings variable has a reference to my_service_account and it is not created yet. The error output is as follows: (...) value of 'count' cannot be computed

Workaround

To avoid this error, use values or attributes of resources that are already created before calling this module.

Note that as soon as the resources have been created once they can be referenced successfully (once they are in the Terraform state file).

Therefore, a simple workaround is as follows:

1. Comment out the call to this module.
2. Run terraform apply to create the other resources and persist them to the state file.
3. Uncomment this module.
4. Run terraform apply to apply the bindings.

IAM Bindings

You can choose the following resources type for apply the IAM bindings:

• Projects (projects variable)
• Organizations(organizations variable)
• Folders (folders variable)
• Service Accounts (service_accounts variable)
• Subnetworks (subnets variable)
• Storage buckets (storage_buckets variable)
• Pubsub topics (pubsub_topics variable)
• Pubsub subscriptions (pubsub_subscriptions variable)
• Kms Key Rings (kms_key_rings variable)
• Kms Crypto Keys (kms_crypto_keys variable)

Set the specified variable on the module call to choose the resources to affect. Remember to set the mode variable and give enough permissions to manage the selected resource as well.

File structure

The project has the following folders and files:

• /: root folder.
• /examples: examples for using this module.
• /scripts: Scripts for specific tasks on module (see Infrastructure section on this file).
• /test: Folders with files for testing the module (see Testing section on this file).
• /main.tf: main file for this module, contains all the logic for operate the module.
• /*_iam.tf: files for manage the IAM bindings for each resource type.
• /variables.tf: all the variables for the module.
• /output.tf: the outputs of the module.
• /readme.MD: this file.

Requirements

Terraform plugins

• Terraform 0.10.x
• terraform-provider-google 1.10.0

jq

• jq 1.5

Permissions

In order to execute this module you must have a Service Account with an appropriate role to manage IAM for the applicable resource. The appropriate role differs depending on which resource you are targeting, as follows:

• Organization:
  • Organization Administrator: Access to administer all resources belonging to the organization and does not include privileges for billing or organization role administration.
  • Custom: Add resourcemanager.organizations.getIamPolicy and resourcemanager.organizations.setIamPolicy permissions.
• Project:
  • Owner: Full access and all permissions for all resources of the project.
  • Projects IAM Admin: allows users to administer IAM policies on projects.
  • Custom: Add resourcemanager.projects.getIamPolicy and resourcemanager.projects.setIamPolicy permissions.
• Folder:
  • The Folder Admin: All available folder permissions.
  • Folder IAM Admin: Allows users to administer IAM policies on folders.
  • Custom: Add resourcemanager.folders.getIamPolicy and resourcemanager.folders.setIamPolicy permissions (must be added in the organization).
• Service Account:
  • Service Account Admin: Create and manage service accounts.
  • Custom: Add resourcemanager.organizations.getIamPolicy and resourcemanager.organizations.setIamPolicy permissions.
• Subnetwork:
  • Project compute admin: Full control of Compute Engine resources.
  • Project compute network admin: Full control of Compute Engine networking resources.
  • Project custom: Add compute.subnetworks.getIamPolicy and compute.subnetworks..setIamPolicy permissions.
• Storage bucket:
  • Storage Admin: Full control of GCS resources.
  • Storage Legacy Bucket Owner: Read and write access to existing buckets with object listing/creation/deletion.
  • Custom: Add storage.buckets.getIamPolicy and storage.buckets.setIamPolicy permissions.
• Pubsub topic:
  • Pub/Sub Admin: Create and manage service accounts.
  • Custom: Add pubsub.topics.getIamPolicy and pubsub.topics.setIamPolicy permissions.
• Pubsub subscription:
  • Pub/Sub Admin role: Create and manage service accounts.
  • Custom role: Add pubsub.subscriptions.getIamPolicy and pubsub.subscriptions.setIamPolicy permissions.
• Kms Key Ring:
  • Owner: Full access to all resources.
  • Cloud KMS Admin: Enables management of crypto resources.
  • Custom: Add cloudkms.keyRings.getIamPolicy and cloudkms.keyRings.getIamPolicy permissions.
• Kms Crypto Key:
  • Owner: Full access to all resources.
  • Cloud KMS Admin: Enables management of cryptoresources.
  • Custom: Add cloudkms.cryptoKeys.getIamPolicy and cloudkms.cryptoKeys.setIamPolicy permissions.

Install

Terraform

Be sure you have the correct Terraform version (0.10.x), you can choose the binary here:

• https://releases.hashicorp.com/terraform/

Terraform plugins

Be sure you have the compiled plugins on $HOME/.terraform.d/plugins/

• terraform-provider-google 1.10.0

See each plugin page for more information about how to compile and use them.

Fast install (optional)

For a fast install, please configure the variables on init_centos.sh or init_debian.sh script and then launch it.

The script will do:

• Environment variables setting
• Installation of base packages like wget, curl, unzip, gcloud, etc.
• Installation of go 1.9.0
• Installation of Terraform 0.10.x
• Download the terraform-provider-google plugin
• Compile the terraform-provider-google plugin
• Move the terraform-provider-google to the right location

Development

Requirements

• bats 0.4.0
• jq 1.5

Integration Tests

The integration tests for this module are built with bats, basically the test checks the following:

• Perform terraform init command
• Perform terraform get command
• Perform terraform plan command and check that it'll create n resources, modify 0 resources and delete 0 resources.
• Perform terraform apply -auto-approve command and check that it has created the n resources, modified 0 resources and deleted 0 resources.
• Perform several gcloud commands and check the IAM bindings are in the desired state.
• Perform terraform destroy -force command and check that it has destroyed the n resources.

Please edit the test/integration/iam-bindings-test/main_test.sh file in order to specify the roles and members to be granted/used.

You can use the following command to run the integration tests in the folder /test/integration/

. launch_additive.sh for additive bindings testing. . launch_authoritative.sh for authoritative bindings testing.

Linting

The makefile in this project will lint or sometimes just format any shell, Python, golang, Terraform, or Dockerfiles. The linters will only be run if the makefile finds files with the appropriate file extension.

All of the linter checks are in the default make target, so you just have to run

make -s

The -s is for 'silent'. Successful output looks like this

Running shellcheck
Running flake8
Running gofmt
Running terraform validate
Running hadolint on Dockerfiles
Test passed - Verified all file Apache 2 headers

The linters are as follows:

• Shell - shellcheck. Can be found in homebrew
• Python - flake8. Can be installed with 'pip install flake8'
• Golang - gofmt. gofmt comes with the standard golang installation. golang is a compiled language so there is no standard linter.
• Terraform - terraform has a built-in linter in the 'terraform validate' command.
• Dockerfiles - hadolint. Can be found in homebrew