Customize an OAuth configuration to enable IAP

This page explains when and how to customize an OAuth configuration for Identity-Aware Proxy (IAP).

IAP uses a Google-managed OAuth client to authenticate users.

The Google-managed OAuth client restricts access to users within the same organization when accessing IAP-enabled applications through a browser.

When to use a custom OAuth configuration

You must use a custom OAuth configuration to do the following:

To allow access to IAP-enabled applications for users outside the organization.
To display your own brand information during authentication.
To enable programmatic access to your application.

When you customize your OAuth configuration, you must configure the OAuth consent screen. This requires that the branding information for your application go through the Google verification process. For more information about the verification process, see Setting up your OAuth consent screen.

You are responsible for creating and managing the credentials for a custom OAuth client. This includes storing the client secret securely and sharing it with authorized users when necessary.

Google managed OAuth client and custom OAuth client comparison

The following table provides a comparison between the Google-managed OAuth client and a custom OAuth client.

	Google managed OAuth client	Custom OAuth client
Users	Internal only	Internal and External
Brand	Google Cloud brand	Customer owned brand
OAuth configuration	Google configured	Customer configured
OAuth credentials	Google managed	Customer managed
Application access	Browser flow only	Browser flow and Programmatic access

Enable IAP using a custom OAuth client configuration

App Engine

Console

Dynamic include file

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.
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 application you want to restrict access to. To turn on IAP for a resource,
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 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
```
Follow the instructions in Creating OAuth clients for IAP to configure the OAuth consent screen and create the OAuth client.
Save the OAuth client ID and secret.

To enable IAP, run the following command.

gcloud iap web enable \
    --oauth2-client-id=CLIENT_ID \
    --oauth2-client-secret=CLIENT_SECRET \
    --resource-type=app-engine \
    --versions=VERSION

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

Follow the instructions in Creating OAuth clients for IAP to configure the OAuth consent screen and create the OAuth client.
Save the OAuth client ID and secret.

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

cat << EOF > settings.json
{
"iap":
  {
    "enabled":true,
    "oauth2ClientId" : CLIENT_ID,
    "oauth2ClientSecret" : CLIENT_SECRET,
  }
}
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://appengine.googleapis.com/v1/apps/PROJECT_ID?updateMask=iap"

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.

Compute Engine

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.

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
```
Follow the instructions in Creating OAuth clients for IAP. to configure the OAuth consent screen and create the OAuth client.
Save the OAuth client ID and secret.

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

Global scope

gcloud compute backend-services update BACKEND_SERVICE_NAME \
    --global \
    --iap=enabled,oauth2-client-id=CLIENT_ID,oauth2-client-secret=CLIENT_SECRET

Regional scope

gcloud compute backend-services update BACKEND_SERVICE_NAME \
    --region REGION_NAME \
    --iap=enabled,oauth2-client-id=CLIENT_ID,oauth2-client-secret=CLIENT_SECRET

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

Follow the instructions in Creating OAuth clients for IAP to configure the OAuth consent screen and create the OAuth client.
Save the OAuth client ID and secret.

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 gcloud CLI to modify the IAP access policy using the IAM role roles/iap.httpsResourceAccessor. Learn more about managing roles and permissions.

Cloud Run

Console

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

Setting up IAP access

Open the Identity-Aware Proxy page.
Go to Identity-Aware Proxy
Select the project you want to secure with IAP.
Under Applications, select the checkbox next to the load balancer backend service to which you want to add members.
On the right side panel, click Add member.
In the Add members dialog, enter the accounts of groups or individuals who should have the IAP-secured Web App User role for the project. The following kinds of accounts can be members:
- Google Account: user@gmail.com - This can also be a Google Workspace account, such as user@google.com or some other Google Workspace domain.
- Google Group: admins@googlegroups.com
- Service account: server@example.gserviceaccount.com
- Google Workspace domain: example.com
Select Cloud IAP > IAP-secured Web App User from the Roles list.
Click Save.

Turning on IAP

On the IAP page, under Applications, find the load balancer backend service to which you want to restrict access. Click the IAP toggle to enable IAP on a resource.
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.
To authorize IAP to send traffic to the backend Cloud Run service, follow the instructions at Add principals to a service to add the following principle and role.
- Principal: service-[PROJECT-NUMBER]@gcp-sa-iap.iam.gserviceaccount.com
- Role: Cloud Run Invoker

gcloud

Follow the instructions in Creating OAuth clients for IAP to configure the OAuth consent screen and create the OAuth client.
Save the OAuth client ID and secret.
If you have not previously done so, create a service account by running the following command. If you previously created a service account, running the command does not create duplicate service accounts.
```
gcloud beta services identity create \
    --service=iap.googleapis.com --project=PROJECT_ID
```

Grant the invoker permission to the service account, created in the previous step, by running the following command.

gcloud run services add-iam-policy-binding SERVICE-NAME \
    --member='serviceAccount:service-PROJECT-NUMBER@gcp-sa-iap.iam.gserviceaccount.com' \
    --role='roles/run.invoker'

Enable IAP by running either the globally or regionally scoped command, depending on whether your load balancer backend service is global or regional. Use the OAuth client ID and secret from the previous step.

Global scope
```
gcloud compute backend-services update BACKEND_SERVICE_NAME \
    --global \
    --iap=enabled,oauth2-client-id=CLIENT_ID,oauth2-client-secret=CLIENT_SECRET
```
Regional scope
```
gcloud compute backend-services update BACKEND_SERVICE_NAME \
    --region REGION_NAME \
    --iap=enabled,oauth2-client-id=CLIENT_ID,oauth2-client-secret=CLIENT_SECRET
```
Replace the following:
- BACKEND_SERVICE_NAME: the name of the backend service.
- CLIENT_ID: the OAuth client ID, from the previous step.
- CLIENT_SECRET: the OAuth client secret, from the previous step.
- REGION_NAME: the region in which you want to enable IAP.

After you enable IAP, you can use the Google Cloud CLI to modify the IAP access policy using the Identity and Access Management role roles/iap.httpsResourceAccessor. See Managing roles and permissions for more information.