Securing Compute Engine apps and resources with IAP

This page explains how to secure a Compute Engine instance with Identity-Aware Proxy (IAP).

To secure resources not on Google Cloud, see Securing on-premises apps and resources.

Before you begin

To enable IAP for Compute Engine, you need the following:

A Google Cloud console project with billing enabled.
A group of one or more Compute Engine instances, served by a load balancer.
- Learn about Setting up an external HTTPS load balancer.
- Learn about setting up an internal HTTP load balancer.
A domain name registered to the address of your load balancer.
Application code to verify that all requests have an identity.
- Learn about Getting the user's identity.

If you don't have your Compute Engine instance set up already, see Setting up IAP for Compute Engine for a complete walkthrough.

IAP uses a Google-managed OAuth client to authenticate users. Only users within the organization can access the IAP-enabled application. If you want to allow access to users outside of your organization, see Enable IAP for external applications.

You can enable IAP on a Compute Engine backend service or on a Compute Engine forwarding rule. When you enable IAP on a Compute Engine backend service, only that backend service is protected by IAP. When you enable IAP on a Compute Engine forwarding rule, all of the Compute Engine instances behind the forwarding rule are protected by IAP.

Enable IAP on a forwarding rule

You can enable IAP on a forwarding rule by using the load balancer authorization policies framework.

gcloud

Run the following command to prepare a policy.yaml file.

$ cat << EOF > policy.yaml
action: CUSTOM
description: authz policy with Cloud IAP
name: AUTHZ_POLICY_NAME
customProvider:
  cloudIap: {}
target:
  loadBalancingScheme: EXTERNAL_MANAGED
  resources:
  - https://www.googleapis.com/compute/v1/projects/PROJECT_ID/regions/LOCATION/forwardingRules/FORWARDING_RULE_ID
EOF

Run the following command to enable IAP on a forwarding rule.

gcloud beta network-security authz-policies import AUTHZ_POLICY_NAME \
--source=policy.yaml \
--location=LOCATION \
--project=PROJECT_ID

Replace the following:

PROJECT_ID: The Google Cloud project ID.
LOCATION: The region that the resource is located in.
FORWARDING_RULE_ID: The ID of the forwarding rule resource.
AUTHZ_POLICY_NAME: The name of the authorization policy.

API

Run the following command to prepare a policy.json file.

cat << EOF > policy.json
{
"name": "AUTHZ_POLICY_NAME",
"target": {
"loadBalancingScheme": "INTERNAL_MANAGED",
"resources": [
"https://www.googleapis.com/compute/v1/projects/PROJECT_ID/regions/LOCATION/forwardingRules/FORWARDING_RULE_ID"
],
},
"action": "CUSTOM",
"httpRules": [],
"customProvider": {
"cloudIap": {}
}
}
EOF

Run the following command to enable IAP on a forwarding rule.
```
curl -X PATCH \
-H "Authorization: Bearer $(gcloud auth print-access-token)" \
-H "Accept: application/json" \
-H "Content-Type: application/json" \
-d @settings.json \
"https://networksecurity.googleapis.com/v1beta1/projects/PROJECT_ID/locations/LOCATION/authzPolicies"
```
Replace the following:
- PROJECT_ID: The Google Cloud project ID.
- LOCATION: The region that the resource is located in.
- FORWARDING_RULE_ID: The ID of the forwarding rule resource.
- AUTHZ_POLICY_NAME: The name of the authorization policy.

After you enable IAP on a forwarding rule, you can apply permissions to resources.

Enable IAP on a Compute Engine backend service

You can enable IAP on a Compute Engine backend service through that backend service.

console

The Google-managed OAuth client is not available when enabling IAP using the Google Cloud console.

If you haven't configured your project's OAuth consent screen, you'll be prompted to do so. To configure your OAuth consent screen, see Setting up your OAuth consent screen.

Setting up IAP access

Go to the Identity-Aware Proxy page.
Go to the Identity-Aware Proxy page
Select the project you want to secure with IAP.
Select the checkbox next to the resource you want to grant access to.

If you don't see a resource, ensure that the resource is created and that the BackendConfig Compute Engine ingress controller is synced.

To verify that the backend service is available, run the following gcloud command:
gcloud compute backend-services list
On the right side panel, click Add principal.
In the Add principals dialog that appears, enter the email addresses of groups or individuals who should have the IAP-secured Web App User role for the project.
The following kinds of principals can have this role:
- Google Account: user@gmail.com
- Google Group: admins@googlegroups.com
- Service account: server@example.gserviceaccount.com
- Google Workspace domain: example.com
Make sure to add a Google Account that you have access to.
Select Cloud IAP > IAP-secured Web App User from the Roles drop-down list.
Click Save.

Turning on IAP

On the Identity-Aware Proxy page, under APPLICATIONS, find the load balancer that serves the instance group you want to restrict access to. To turn on IAP for a resource, toggle the on/off switch in the IAP column.
To enable IAP:
- At least one protocol in the load balancer frontend configuration must be HTTPS. Learn about setting up a load balancer.
- You need the compute.backendServices.update, clientauthconfig.clients.create, and clientauthconfig.clients.getWithSecret permissions. These permissions are granted by roles, such as the Project Editor role. To learn more, see Managing access to IAP-secured resources.
In the Turn on IAP window that appears, click Turn On to confirm that you want IAP to secure your resource. After you turn on IAP, it requires login credentials for all connections to your load balancer. Only accounts with the IAP-Secured Web App User role on the project will be given access.

gcloud

Before you set up your project and IAP, you need an up-to-date version of the gcloud CLI. For instructions on how to install the gcloud CLI, see Install the gcloud CLI.

To authenticate, use the Google Cloud CLI and run the following command.
```
gcloud auth login
```
To sign in, follow the URL that appears.
After you sign in, copy the verification code that appears and paste it in the command line.
Run the following command to specify the project that contains the resource that you want to protect with IAP.
```
gcloud config set project PROJECT_ID
```

To enable IAP, run either the globally or regionally scoped command.

Global scope

gcloud compute backend-services update BACKEND_SERVICE_NAME --global --iap=enabled

Regional scope

gcloud compute backend-services update BACKEND_SERVICE_NAME --region REGION_NAME --iap=enabled

After you enable IAP, you can use the gcloud CLI to modify the IAP access policy using the IAM role roles/iap.httpsResourceAccessor. Learn more about managing roles and permissions.

API

Run the following command to prepare a settings.json file.

cat << EOF > settings.json
{
"iap":
  {
    "enabled":true
  }
}
EOF

Run the following command to enable IAP.

curl -X PATCH \
-H "Authorization: Bearer $(gcloud auth print-access-token)" \
-H "Accept: application/json" \
-H "Content-Type: application/json" \
-d @settings.json \
"https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/REGION/backendServices/BACKEND_SERVICE_NAME"

After you enable IAP, you can use the Google Cloud CLI to modify the IAP access policy using the IAM role roles/iap.httpsResourceAccessor. Learn more about managing roles and permissions.

Next steps

Set richer context rules by applying access levels.
See access requests by enabling Cloud Audit Logs.
Learn more about IAP.