Managing OS Login in an organization

If you use OS Login to manage access to your instances, you can set configurations at the organization level for your Cloud Identity account. For example, you can control who can directly use the OS Login API, enable OS Login for all VM instances in an organization, and grant access to external users.

Note: To complete any of the tasks detailed in this page, you must be a G Suite administrator.

This topic covers the following tasks:

• Enabling OS Login for an organization using an organization policy: Use an organization policy to ensure that all new VM instances in your organization have OS Login enabled.
• Granting instance access to users outside of your organization: Allow user accounts outside of your organization to use SSH to connect to your instances.
• Managing the OS Login API: Allow or deny users access to use the OS Login API. Also enable or disable features of the OS Login API.
• Auditing OS Login events: Track OS Login-related events and activities such as adding, deleting, or updating an SSH key, or deleting POSIX information.
• Modifying user accounts using the Directory API: Update user properties, such as username and POSIX account information, by using the Directory API.

Before you begin

• If you want to use the command-line examples in this guide:
  1. Install or update to the latest version of the gcloud command-line tool.
  2. Set a default region and zone.
• If you want to use the API examples in this guide, set up API access.

Enabling OS Login using an organization policy

You can set up an OS Login constraint in your organization to ensure that all new projects, and the VM instances created in these new projects, have OS Login enabled.

When this constraint is set up, the following conditions are applied:

• enable-oslogin is set to true in the project metadata for all new projects.
• Update requests to set enable-oslogin to false in instance or project metadata are rejected.

Limitations

• You cannot apply this constraint retroactively. OS Login is not automatically enabled on instances and projects that are created before the constraint is applied.

• Instances running in Google Kubernetes Engine do not support OS Login. Enabling the OS Login constraint prevents Google Kubernetes Engine clusters from creating new instances in projects where the constraint applies.

  To work around this issue, you can enable this constraint at the organization level and then selectively disable the constraint in projects that have Google Kubernetes Engine clusters. Alternatively, you can choose to enable OS Login at either the project or folder level. For more information about managing organization policies, see creating and managing organization policies.

Permissions required for this task

To perform this task, you must have the following permissions:

• resourcemanager.organizationAdmin role. For more information see,Access control for organizations using IAM.
• To learn more about managing policies at the organization level, see Add an organization policy administrator.

To enable the OS Login policy, you can set the OS Login constraint on specific projects and folders by using the gcloud command-line tool. You can also set the OS Login constraint on the entire organization by using either the Google Cloud Console or the gcloud command-line tool.

Console

To set the OS Login organization policy from the console, complete the following steps:

1. In the Google Cloud Console, go to the Organization policies page.

   Go to the Organization policies page

2. In the policies list, click Require OS Login to view the OS Login constraints.
3. Click Edit to edit your existing OS Login constraints.
4. On the Edit page, select Customize.
5. To enable enforcement of this constraint, select On.
6. Click Save to apply the constraint settings.

gcloud

To set the OS Login organization policy, use the gcloud beta resource-manager org-policies enable-enforce command.

1. Find your organization ID.

   gcloud organizations list

2. Set the constraint in your organization. Replace organization-id with your your organization ID.

   gcloud beta resource-manager org-policies enable-enforce compute.requireOsLogin \
       --organization=organization-id
   

You can also apply the OS Login organization policy to a folder or a project with the --folder or the --project flags, and the folder ID and project ID, respectively.

For folders, run the following command:

gcloud beta resource-manager org-policies enable-enforce compute.requireOsLogin \
    --folder=folder-id

For projects, run the following command:

gcloud beta resource-manager org-policies enable-enforce compute.requireOsLogin \
    --project=project-id

Replace the following:

• folder-id: Your folder ID.
• project-id: Your project ID.

Granting instance access to users outside of your organization

Note: If your project is part of an organization, you can grant instance access to users who are outside of your organization by using roles/compute.osLoginExternalUser or by using a custom role with the compute.oslogin.updateExternalUser permission.

By default, users outside of your organization can't set SSH keys for instances in your organization or be granted access to instances in your organization. In some situations, you might need to grant instance access to users who are part of a different organization or who have a consumer Google gmail.com account.

The roles/compute.osLoginExternalUser IAM role lets external Google Accounts interact with the other OS Login roles by allowing them to configure POSIX account information.

To grant roles/compute.osLoginExternalUser and other necessary OS Login instance access roles to users outside of your organization, complete the following steps:

1. In the Google Cloud Console, go to the go to the project and organization selection page.

   Go to the project and organization selection page

2. In the Organization drop-down menu, select your organization.
   1. Click All, to view all of your organizations.
   2. Click the name of the organization.
3. Click Add to add a new role to a user.
4. Specify the user name for the user for whom you want to configure instance access.
5. Click Select a role to specify which roles you want to grant to the users.
6. In the Compute Engine roles list, select the Compute OS Login External User role.
7. Click Add to confirm that you want to grant the selected role to the user.
8. If you have not already done so, grant the other OS Login instance access roles to the user at the project or organization level.

The user can now connect to instances in your project that have OS Login enabled.

Managing the OS Login API

At an organization level, you can restrict access to the OS Login API by setting G Suite admin controls. To configure G Suite admin controls or view configuration options, see Control who uses Google Cloud in your organization. As a G Suite admin, you can also turn on or off certain features of the OS Login API. This includes the following options:

• Choose whether to include the domain suffix in usernames generated by OS Login API. For example, in the domain example.com, the user [e-mail] will have the username user if the setting to include domain suffix is not checked.
• Decide if members of your organization can manage SSH keys using the OS Login API.
• Restrict or permit VM access to users outside of your organization.

For more information about turning on or off OS Login API settings, see Choose settings for Google Cloud Platform.

Auditing OS Login events

As a G Suite Admin, you can use the G Suite Admin SDK to audit actions performed with the OS Login API. By reviewing these events, you can track when a user adds, deletes, or updates an SSH key, or deletes POSIX account information.

You can retrieve OS Login API audit activity events, from the G Suite Admin SDK, by calling Activities.list() with applicationName=gcp. For more information, see Google Cloud activity events in the G Suite Admin SDK Reports API documentation.

Modifying user accounts using the Directory API

OS Login uses either your Cloud Identity or G Suite user settings when connecting to an instance. If you are an organization admin, you can use the Directory API to complete the following tasks for your G Suite or Cloud Identity user accounts:

• Modify instance login settings.
• Make a user an administrator
• Modify user properties such as account name and email
• Add and remove SSH keys for a user
• Modify POSIX account information
• Change the username that the users connect to on the instance.

For more information about the account properties that you can edit, see the Directory API reference.

For example, create a PUT request to the directory.users.update method and specify one or more properties to change on the user account:

PUT https://www.googleapis.com/admin/directory/v1/users/user-id-key

{
 "posixAccounts": [
   {
    "username": "user-name",
    "uid": "uid",
    "gid": "gid",
    "homeDirectory": "user-home-path",
    "shell": "shell-path"
   }
  ],
}

Replace the following:

• user-id-key: An immutable ID for the user.
• user-name: The username that Compute Engine adds to the instance for the user. This value must be unique within your organization. This user-name must not end in a tilde ("~") or contain a period (".") as this might cause issues when running sudo commands on the VM.
• uid: The user ID on the instance for this user. This property must be a value between 1001 and 60000, or a value between 65535 and 2147483647. To access a container-optimized OS, the UID must have value between 65536 and 214748646. The UID must be unique within your organization.
• gid: The group ID on the instance that this user belongs to.
• user-home-path: The home directory on the instance for this user. For example, /home/example_username.
• shell-path: The path to the default shell for the user after they connect to the instance. For example, /bin/bash or /bin/sh.

Note: Do not update the systemID property. The systemID property must be left blank.

What's next

• Learn how to set up OS Login.
• Learn how to set up OS Login with two-factor authentication.
• Read an overview of the OS Login feature.