Using Images from Other Projects

This page describes how to configure your project so that Deployment Manager can create Compute Engine virtual machine instances using operating system images that belong to another project.

For example, assume you have a project named Awesome Project where Deployment Manager creates and manages VM instances. Now, let's assume you need to use private images that belong to a different project named Database Images. To grant access to these images, the owner of Database Images must grant the IAM role roles/compute.imageUser to the Google APIs service account of Awesome Project, and Awesome Project can then use images from the Database Images project.

You can also use this process to grant managed instance groups access to images from other projects.

Before you begin

If you want to use the command-line examples in this guide, install the `gcloud` command-line tool.
If you want to use the API examples in this guide, set up API access.
Read about Deployment Manager configurations.
Read about Compute Engine private images.
Read about Identity and Access Management (IAM) documentation.
Read about Deployment Manager IAM roles, in particular, the roles/compute.imageUser role.

Limitations

The following are restrictions for using this feature:

You must grant the compute.imageUser role on the project level to your project's Google APIs service account.
Granting the compute.imageUser role grants permissions to all images in the specific project. It is not possible to share specific images.
You must grant this role to specific users, and not to allAuthenticatedUsers or allUsers.

Granting access to images

To grant access to images that belong to another project, the owner of the project that owns the images must grant access to the Google APIs service account of the project that wants to use the images.

Go to the IAM page in the Google Cloud console of the project that needs access to private images owned by another project.
Go to the IAM page
If prompted, select your project from the list. Remember to select the project that needs access to images stored in another project.
Look for Google APIs service account, which has an email address in the following format:
```
[PROJECT_NUMBER]@cloudservices.gserviceaccount.com
```
Note: This email address requires the project number, which is different than the project ID. To learn how to identify the project number, see Identifying projects.
Make note of the email address above. Next, a project owner of the project where the desired images live can grant the Google APIs service account the roles/compute.imageUser role.
Console
1. While still in the Google Cloud console, go to the IAM page of the project that contains the images you want access to.
  Go to the IAM page
2. Select the project from the project list.
3. Click the Add button to add a new member.
4. In the Members box, enter the email address of the service account.
5. Expand the Roles dropdown and select Compute Engine > Compute Image User.
6. Click Add to add the account.
gcloud
With the Google Cloud CLI, add a binding to the IAM policy for the project:
```
gcloud projects add-iam-policy-binding [PROJECT_ID] \
    --member serviceAccount:[SERVICE_ACCOUNT_EMAIL] --role roles/compute.imageUser
```
where:
- [PROJECT_ID] is the ID of the project containing images you want to share.
- [SERVICE_ACCOUNT_EMAIL] is the email of the service account.
For example:
```
gcloud projects add-iam-policy-binding database-images \
    --member serviceAccount:123456789012@cloudservices.gserviceaccount.com  \
    --role roles/compute.imageUser
```
API
In the API, make a POST request to the following URL, where [PROJECT_ID] is the ID of the project containing the images you want to share.
```
POST https://cloudresourcemanager.googleapis.com/v1/projects/$[PROJECT_ID]:setIamPolicy
```
The request body should contain the list of bindings you want to apply to this project. The roles/compute.imageUser role should be part of the binding. For example:
```
{
   "policy": {
       "version": "0",
       "bindings": [
       {
           "role": "roles/owner",
           "members": [
               "user:example@gmail.com"
           ]
       },
       {
           "role": "roles/compute.imageUser",
           "members": [
               "serviceAccount:123456789012@cloudservices.gservbiceaccount.com"
           ]
       }
       ]
   }
```
}