Vault OIDC Google Provider Configuration

vault-oidc-google-config.sh

#!/bin/bash

# Configures Vault's OIDC authentication method to use Google as the provider.

# It retrieves the client ID and client secret from Vault, formats the GSuite service account
# JSON as required by Vault, and writes the configuration to Vault using the "gsuite" provider.
# This script assumes that Vault has already been initialized and unsealed, and that the OIDC
# authentication method has been enabled. 

# Write first your Google Cloud Platform (GCP) credentials to HashiCorp Vault using 
# https://gist.github.com/zboralski/709b2427bff863ab7868c6a1d2125591#file-vault-oidc-google-secrets-sh

# OIDC Provider Configuration | Google
# https://developer.hashicorp.com/vault/docs/auth/jwt/oidc-providers/google


# Set project and service account variables
PROJECT="example-vault-us"
SERVICE_ACCOUNT="example-vault-us-1aab5d7d48ab.json"

# Set the email address of the GSuite admin
GSUITE_ADMIN="user@example.com"

# Set secret paths
SECRET_ROOT="secret/gcloud/${PROJECT}"
SERVICE_ACCOUNT_SECRET="${SECRET_ROOT}/gsuite_service_account"
CLIENT_SECRET="${SECRET_ROOT}/client_secret"

# Retrieve the service account from Vault, format it as JSON, and encode it again with properly escaped characters
GSUITE_SERVICE_ACCOUNT=$(vault kv get -format=json ${SERVICE_ACCOUNT_SECRET} | \
  jq -c '.data.data' | jq -c '. |= @json')

# Set OIDC config variables
OIDC_CONFIG="auth/oidc/config"
OIDC_DISCOVERY_URL="https://accounts.google.com"
OIDC_CLIENT_ID=$(vault kv get -format=json "${CLIENT_SECRET}"  | jq -r '.data.data.client_id')
OIDC_CLIENT_SECRET=$(vault kv get -format=json "${CLIENT_SECRET}"  | jq -r '.data.data.client_secret')

# Write the OIDC config to Vault using a heredoc
vault write "${OIDC_CONFIG}" -<<EOF
{
  "oidc_discovery_url": "${OIDC_DISCOVERY_URL}",
  "oidc_client_id": "${OIDC_CLIENT_ID}",
  "oidc_client_secret": "${OIDC_CLIENT_SECRET}",
  "default_role": "default",
  "provider_config": {
    "provider": "gsuite",
    "gsuite_service_account": ${GSUITE_SERVICE_ACCOUNT},
    "gsuite_admin_impersonate": "${GSUITE_ADMIN}",
    "fetch_groups": true,
    "fetch_user_info": true,
    "groups_recurse_max_depth": 5,
    "user_custom_schemas": "Preferences"
  }
}
EOF