Enabling GitHub Actions with Google Cloud Storage

Note: GitHub Actions support for Google Cloud Storage is currently in beta and subject to change.

About external storage for GitHub Actions

GitHub Actions uses external blob storage to store data generated by workflow runs. Stored data includes workflow logs, caches, and user-uploaded build artifacts. For more information, see "Getting started with GitHub Actions for GitHub Enterprise Server."

There are two options for configuring GitHub Enterprise Server to connect to your external storage provider:

OpenID Connect (OIDC)
Traditional credentials-based authentication using secrets

We recommend using OIDC where possible, as you won't need create or manage sensitive and long-lived credential secrets for your storage provider, and risk them being exposed. After defining a trust with OIDC, your cloud storage provider automatically issues short-lived access tokens to your GitHub Enterprise Server instance, which automatically expire.

Prerequisites

Before enabling GitHub Actions, make sure you have completed the following steps:

Create your Google Cloud Storage bucket for storing data generated by workflow runs.
Review the hardware requirements for GitHub Actions. For more information, see "Getting started with GitHub Actions for GitHub Enterprise Server."
TLS must be configured for your GitHub Enterprise Server instance's domain. For more information, see "Configuring TLS."

Note: We strongly recommend that you configure TLS on GitHub Enterprise Server with a certificate signed by a trusted authority. Although a self-signed certificate can work, extra configuration is required for your self-hosted runners, and it is not recommended for production environments.
If you have an HTTP Proxy Server configured on your GitHub Enterprise Server instance:
You must add .localhost and 127.0.0.1 to the HTTP Proxy Exclusion list.
If your external storage location is not routable, then you must also add your external storage URL to the exclusion list.

For more information on changing your proxy settings, see "Configuring an outbound web proxy server."

If you are using OIDC for the connection to your storage provider, you must expose the following OIDC token service URLs on your GitHub Enterprise Server instance to the public internet:
```
https://HOSTNAME/_services/token/.well-known/openid-configuration
https://HOSTNAME/_services/token/.well-known/jwks
```
This ensures that the storage provider can contact your GitHub Enterprise Server instance for authentication.

Enabling GitHub Actions with Google Cloud Storage using OIDC (recommended)

To configure GitHub Enterprise Server to use OIDC with Google Cloud Storage, you must first create a Google Cloud service account, then create a Google Cloud identity pool and identity provider, and finally configure GitHub Enterprise Server to use the provider and service account to access your Google Cloud Storage bucket.

1. Create a service account

Create a service account that can access your bucket using OIDC. For more information, see Creating and managing service accounts in the Google Cloud documentation.

When creating the service account, ensure that you do the following:
- Enable the IAM API as described at the start of Creating and managing service accounts.
- Add the following roles to the service account:
  - Service Account Token Creator
  - Storage Object Admin
After creating the service account, note its email address, as it is need later. The service account email address is in the format SERVICE-ACCOUNT-NAME@PROJECT-NAME.iam.gserviceaccount.com.

2. Create an identity pool and identity provider

In the Google Cloud console, go to the New workload provider and pool page.
Under "Create an identity pool", enter a name for the identity pool, and click Continue.
Under "Add a provider to pool":
- For "Select a provider", select OpenID Connect (OIDC).
- For "Provider name", enter a name for the provider.
- For "Issuer (URL)", enter the following URL, replacing HOSTNAME with the public hostname for your GitHub Enterprise Server instance:
```
https://HOSTNAME/_services/token
```
  For example:
```
https://my-ghes-host.example.com/_services/token
```
- Under "Audiences", leave Default audience selected, but note the identity provider URL, as it is needed later. The identity provider URL is in the format https://iam.googleapis.com/projects/PROJECT-NUMBER/locations/global/workloadIdentityPools/POOL-NAME/providers/PROVIDER-NAME.
- Click Continue.
Under "Configure provider attributes":
- For the "OIDC 1" mapping, enter assertion.sub.
- Under "Attribute Conditions", click Add condition.
- For "Condition CEL", enter the following condition, replacing HOSTNAME with the public hostname for your GitHub Enterprise Server instance:
```
google.subject == "HOSTNAME"
```
  For example:
```
google.subject == "my-ghes-host.example.com"
```
  Note: The hostname of your GitHub Enterprise Server instance used here must not include the protocol.
- Click Save.
After creating the identity pool, at the top of the identity pool's page, click Grant access.
- Under "Select service account", select the service account that you created in the previous procedure.
- Under "Select principals (identities that can access the service account)", select Only identities matching the filter.
- For "Attribute name", select subject.
- For "Attribute value", enter your GitHub Enterprise Server hostname, without the protocol. For example, my-ghes-host.example.com.
- Click Save.
- You can dismiss the "Configure your application" dialog, as the configuration file is not needed.

3. Configure GitHub Enterprise Server to connect to Google Cloud Storage using OIDC

From an administrative account on GitHub Enterprise Server, in the upper-right corner of any page, click .
If you're not already on the "Site admin" page, in the upper-left corner, click Site admin.
In the " Site admin" sidebar, click Management Console.
In the "Settings"" sidebar, click Actions.
Under "GitHub Actions", select Enable GitHub Actions.
Under "Artifact & Log Storage", next to "Google Cloud Storage", click Setup.
Under "Authentication", select OpenID Connect (OIDC), and enter the values for your storage:
- Service URL: The service URL for your bucket. This is usually https://storage.googleapis.com.
- Bucket name: The name of your bucket.
- Workload Identity Provider ID: The identity provider ID for your identity pool.
  
  This is in the format projects/PROJECT-NUMBER/locations/global/workloadIdentityPools/POOL-NAME/providers/PROVIDER-NAME. Note that you must remove the https://iam.googleapis.com/ prefix from the value noted in the previous procedure.
  
  For example, projects/1234567890/locations/global/workloadIdentityPools/my-pool/providers/my-provider.
- Service account: The service account email address that you noted in the previous procedure. For example, ghes-oidc-service-account@my-project.iam.gserviceaccount.com.
Click the Test storage settings button to validate your storage settings.

If there are any errors validating the storage settings, check the settings with your storage provider and try again.
Under the "Settings" sidebar, click Save settings.

Note: Saving settings in the Management Console restarts system services, which could result in user-visible downtime.
Wait for the configuration run to complete.

Enabling GitHub Actions with Google Cloud Storage using a HMAC key

Create a Google Cloud service account that can access the bucket, and create a Hash-based Message Authentication Code (HMAC) key for the service account. For more information, see "Manage HMAC keys for service accounts" in the Google Cloud documentation.

The service account must have the following Identity and Access Management (IAM) permissions for the bucket:
- storage.objects.create
- storage.objects.get
- storage.objects.list
- storage.objects.update
- storage.objects.delete
- storage.multipartUploads.create
- storage.multipartUploads.abort
- storage.multipartUploads.listParts
- storage.multipartUploads.list
From an administrative account on GitHub Enterprise Server, in the upper-right corner of any page, click .
If you're not already on the "Site admin" page, in the upper-left corner, click Site admin.
In the " Site admin" sidebar, click Management Console.
In the "Settings"" sidebar, click Actions.
Under "GitHub Actions", select Enable GitHub Actions.
Under "Artifact & Log Storage", next to "Google Cloud Storage", click Setup.
Under "Authentication", select Credentials-based, and enter your storage bucket's details:
- Service URL: The service URL for your bucket. This is usually https://storage.googleapis.com.
- Bucket Name: The name of your bucket.
- HMAC Access Id and HMAC Secret: The Google Cloud access ID and secret for your storage account. For more information, see "Manage HMAC keys for service accounts" in the Google Cloud documentation.
Click the Test storage settings button to validate your storage settings.

If there are any errors validating the storage settings, check the settings with your storage provider and try again.
Under the "Settings" sidebar, click Save settings.

Note: Saving settings in the Management Console restarts system services, which could result in user-visible downtime.
Wait for the configuration run to complete.

Next steps

After the configuration run has successfully completed, GitHub Actions will be enabled on your GitHub Enterprise Server instance. For your next steps, such as managing GitHub Actions access permissions and adding self-hosted runners, return to "Getting started with GitHub Actions for GitHub Enterprise Server."

Who can use this feature?

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