Vault Plugin: Google Cloud Platform Auth Backend

This is a backend plugin to be used with Hashicorp Vault. This plugin generates either one-time (non-renewable) OAuth2 access tokens or service account keys with a given set of IAM roles bound to GCP resources for various GCP entities to authenticate with Vault.

Please note: We take Vault's security and our users' trust very seriously. If you believe you have found a security issue in Vault or with this plugin, please responsibly disclose by contacting us at security@hashicorp.com.

Quick Links

Usage

This is a Vault plugin and is meant to work with Vault. This guide assumes you have already installed Vault and have a basic understanding of how Vault works. Otherwise, first read this guide on how to get started with Vault.

If you are using Vault v0.9.6 or above, this plugin is packaged with Vault and by default can be enabled by running:

$ vault secrets enable gcp

Success! Enabled the gcp secrets engine at: gcp/

If you are testing this plugin in an earlier version of Vault or want to develop, see the next section.

Developing

If you wish to work on this plugin, you'll first need Go installed on your machine (whichever version is required by Vault).

Make sure Go is properly installed, including setting up a GOPATH.

Get Plugin

Clone this repository:


mkdir $GOPATH/src/github.com/hashicorp/vault-plugin-secrets-gcp`
cd $GOPATH/src/github.com/hashicorp/
git clone https://github.com/hashicorp/vault-plugin-secrets-gcp.git

(or use go get github.com/hashicorp/vault-plugin-secrets-gcp ).

You can then download any required build tools by bootstrapping your environment:

$ make bootstrap

To compile a development version of this plugin, run make or make dev. This will put the plugin binary in the bin and $GOPATH/bin folders. dev mode will only generate the binary for your platform and is faster:

$ make
$ make dev

Install Plugin in Vault

Put the plugin binary into a location of your choice. This directory will be specified as the plugin_directory in the Vault config used to start the server.

plugin_directory = "path/to/plugin/directory"

Start a Vault server with this config file:

$ vault server -config=path/to/config.json ...

Once the server is started, register the plugin in the Vault server's plugin catalog:

$ vault write sys/plugins/catalog/gcpsecrets \
        sha_256="$(shasum -a 256 path/to/plugin/directory/vault-plugin-secrets-gcp | cut -d " " -f1)" \
        command="vault-plugin-secrets-gcp"

Any name can be substituted for the plugin name "mygcpplugin". This name will be referenced in the next step, where we enable the auth plugin backend using the GCP auth plugin:

$ vault secrets enable --plugin-name='gcpsecrets' --path="gcp" plugin

Tests

This plugin has acceptance tests covering most of the features of this auth backend.

If you are developing this plugin and want to verify it is still functioning (and you haven't broken anything else), we recommend running the acceptance tests.

Acceptance tests typically require other environment variables to be set for things such as access keys. The test itself should error early and tell you what to set, so it is not documented here.

Warning: The acceptance tests create/destroy/modify real resources, which may incur real costs in some cases. In the presence of a bug, it is technically possible that broken backends could leave dangling data behind. Therefore, please run the acceptance tests at your own risk. At the very least, we recommend running them in their own private account for whatever backend you're testing.

To run the acceptance tests, invoke make test:

$ make test

You can also specify a TESTARGS variable to filter tests like so:

$ make test TESTARGS='--run=TestConfig'

Auto-generated IAM Config

An IAM-enabled resource (under an arbitrary GCP service) supports the following three IAM methods:

getIamPolicy
setIamPolicy
testIamPermissions

In the case of this secrets engine, we need to call getIamPolicy and setIamPolicy on an arbitrary resource under an arbitrary service, which would be difficult using the generated Go google APIs. Instead, we autogenerated a library, using the Google API Discovery Service to find IAM-enabled resources and configure HTTP calls on arbitrary services/resources for IAM.

For each binding config resource block (with a resource name), we attempt to find the resource type based on the relative resource name and match it to a service config as seen in this autogenerated config file

To re-generate this file, run:

go generate github.com/hashicorp/vault-plugin-secrets-gcp/plugin/iamutil

In general, we try to make it so you can specify the resource as given in the HTTP API URL (between base API URL and get/setIamPolicy suffix). For some possibly non-standard APIs, we have also added exceptions to try to reach something more standard; a notable current example is the Google Cloud Storage API, whose methods look like https://www.googleapis.com/storage/v1/b/bucket/o/object where we accept either b/bucket/o/object or buckets/bucket/objects/object as valid relative resource names.

If you are having trouble during role set creation with errors suggesting the resource format is invalid or API calls are failing for a resource you know exists, please report any issues you run into. It could be that the API is a non-standard form or we need to re-generate our config file.

Other Docs (To Be Removed/Replaced)

See up-to-date HTTP API Docs and general GCP engine docs

rpahli/vault-plugin-secrets-gcp