Object storage

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GitLab supports using an object storage service for holding numerous types of data. It's recommended over NFS and in general it's better in larger setups as object storage is typically much more performant, reliable, and scalable.

To configure the object storage, you have two options:

• Recommended. Configure a single storage connection for all object types: A single credential is shared by all supported object types. This is called the consolidated form.

• Configure each object type to define its own storage connection: Every object defines its own object storage connection and configuration. This is called the storage-specific form.

  If you already use the storage-specific form, see how to transition to the consolidated form.

If you store data locally, see how to migrate to object storage.

Supported object storage providers

GitLab is tightly integrated with the Fog library, so you can see which providers can be used with GitLab.

Specifically, GitLab has been tested by vendors and customers on a number of object storage providers:

• Amazon S3 (Object Lock is not supported, see issue #335775 for more information)
• Google Cloud Storage
• Digital Ocean Spaces (S3 compatible)
• Oracle Cloud Infrastructure
• OpenStack Swift (S3 compatible mode)
• Azure Blob storage
• MinIO (S3 compatible)
• On-premises hardware and appliances from various storage vendors, whose list is not officially established.

Configure a single storage connection for all object types (consolidated form)

Most types of objects, such as CI artifacts, LFS files, and upload attachments can be saved in object storage by specifying a single credential for object storage with multiple buckets.

NOTE: For GitLab Helm Charts, see how to configure the consolidated form.

Configuring the object storage using the consolidated form has a number of advantages:

• It can simplify your GitLab configuration since the connection details are shared across object types.
• It enables the use of encrypted S3 buckets.
• It uploads files to S3 with proper Content-MD5 headers.

When the consolidated form is used, direct upload is enabled automatically. Thus, only the following providers can be used:

• Amazon S3-compatible providers
• Google Cloud Storage
• Azure Blob storage

The consolidated form configuration can't be used for backups or Mattermost. Backups can be configured with server side encryption separately. See the table for a complete list of supported object storage types.

Enabling the consolidated form enables object storage for all object types. If not all buckets are specified, you may see an error like:

Object storage for <object type> must have a bucket specified

If you want to use local storage for specific object types, you can disable object storage for specific features.

Configure the common parameters

In the consolidated form, the object_store section defines a common set of parameters.

For an example, see how to use the consolidated form and Amazon S3.

Configure the parameters of each object

Each object type must at least define the bucket name where it will be stored.

The following table lists the valid objects that can be used:

Within each object type, three parameters can be defined:

For an example, see how to use the consolidated form and Amazon S3.

Disable object storage for specific features

As seen above, object storage can be disabled for specific types by setting the enabled flag to false. For example, to disable object storage for CI artifacts:

gitlab_rails['object_store']['objects']['artifacts']['enabled'] = false

A bucket is not needed if the feature is disabled entirely. For example, no bucket is needed if CI artifacts are disabled with this setting:

gitlab_rails['artifacts_enabled'] = false

Configure each object type to define its own storage connection (storage-specific form)

With the storage-specific form, every object defines its own object storage connection and configuration. You should use the consolidated form instead, except for the storage types not supported by the consolidated form. When working with the GitLab Helm charts, refer to how the charts handle consolidated form for object storage.

The use of encrypted S3 buckets with non-consolidated form is not supported. You may get ETag mismatch errors if you use it.

NOTE: For the storage-specific form, direct upload may become the default because it does not require a shared folder.

For storage types not supported by the consolidated form, refer to the following guides:

Configure the connection settings

Both consolidated and storage-specific form must configure a connection. The following sections describe parameters that can be used in the connection setting.

Amazon S3

The connection settings match those provided by fog-aws:

Use Amazon instance profiles

Instead of supplying AWS access and secret keys in object storage configuration, you can configure GitLab to use Amazon Identity Access and Management (IAM) roles to set up an Amazon instance profile. When this is used, GitLab fetches temporary credentials each time an S3 bucket is accessed, so no hard-coded values are needed in the configuration.

Prerequisites:

• GitLab must be able to connect to the instance metadata endpoint.
• If GitLab is configured to use an internet proxy, the endpoint IP address must be added to the no_proxy list.

To set up an instance profile:

1. Create an IAM role with the necessary permissions. The following example is a role for an S3 bucket named test-bucket:

   {
       "Version": "2012-10-17",
       "Statement": [
           {
               "Sid": "VisualEditor0",
               "Effect": "Allow",
               "Action": [
                   "s3:PutObject",
                   "s3:GetObject",
                   "s3:DeleteObject"
               ],
               "Resource": "arn:aws:s3:::test-bucket/*"
           }
       ]
   }

2. Attach this role to the EC2 instance hosting your GitLab instance.

3. Set the use_iam_profile GitLab configuration option to true.

Encrypted S3 buckets

When configured either with an instance profile or with the consolidated form, GitLab Workhorse properly uploads files to S3 buckets that have SSE-S3 or SSE-KMS encryption enabled by default. AWS KMS keys and SSE-C encryption are not supported since this requires sending the encryption keys in every request.

Server-side encryption headers

Setting a default encryption on an S3 bucket is the easiest way to enable encryption, but you may want to set a bucket policy to ensure only encrypted objects are uploaded. To do this, you must configure GitLab to send the proper encryption headers in the storage_options configuration section:

As with the case for default encryption, these options only work when the Workhorse S3 client is enabled. One of the following two conditions must be fulfilled:

• use_iam_profile is true in the connection settings.
• Consolidated form is in use.

ETag mismatch errors occur if server side encryption headers are used without enabling the Workhorse S3 client.

Oracle Cloud S3

Oracle Cloud S3 must be sure to use the following settings:

If enable_signature_v4_streaming is set to true, you may see the following error in production.log:

STREAMING-AWS4-HMAC-SHA256-PAYLOAD is not supported

Google Cloud Storage (GCS)

Here are the valid connection parameters for GCS:

GitLab reads the value of google_json_key_location, then google_json_key_string, and finally, google_application_default. It uses the first of these settings that has a value.

The service account must have permission to access the bucket. For more information, see the Cloud Storage authentication documentation.

NOTE: To use bucket encryption with customer-managed encryption keys, use the consolidated form.

GCS example

For Linux Package installations, this is an example of the connection setting in the consolidated form:

gitlab_rails['object_store']['connection'] = {
  'provider' => 'Google',
  'google_project' => '<GOOGLE PROJECT>',
  'google_json_key_location' => '<FILENAME>'
}

GCS example with ADC

Google Cloud Application Default Credentials (ADC) are typically used with GitLab to use the default service account. This eliminates the need to supply credentials for the instance. For example, in the consolidated form:

gitlab_rails['object_store']['connection'] = {
  'provider' => 'Google',
  'google_project' => '<GOOGLE PROJECT>',
  'google_application_default' => true
}

If you use ADC, be sure that:

• The service account that you use has the iam.serviceAccounts.signBlob permission. Typically this is done by granting the Service Account Token Creator role to the service account.

• Your virtual machines have the correct access scopes to access Google Cloud APIs. If the machines do not have the right scope, the error logs may show:

  Google::Apis::ClientError (insufficientPermissions: Request had insufficient authentication scopes.)

Azure Blob storage

Although Azure uses the word container to denote a collection of blobs, GitLab standardizes on the term bucket. Be sure to configure Azure container names in the bucket settings.

Azure Blob storage can only be used with the consolidated form because a single set of credentials are used to access multiple containers. The storage-specific form is not supported. For more details, see how to transition to consolidated form.

The following are the valid connection parameters for Azure. For more information, see the Azure Blob Storage documentation.

• For Linux package installations, this is an example of the connection setting in the consolidated form:

  gitlab_rails['object_store']['connection'] = {
    'provider' => 'AzureRM',
    'azure_storage_account_name' => '<AZURE STORAGE ACCOUNT NAME>',
    'azure_storage_access_key' => '<AZURE STORAGE ACCESS KEY>',
    'azure_storage_domain' => '<AZURE STORAGE DOMAIN>'
  }

• For self-compiled installations, Workhorse also needs to be configured with Azure credentials. This isn't needed in Linux package installations because the Workhorse settings are populated from the previous settings.

  1. Edit /home/git/gitlab-workhorse/config.toml and add or amend the following lines:

     [object_storage]
       provider = "AzureRM"
     
     [object_storage.azurerm]
       azure_storage_account_name = "<AZURE STORAGE ACCOUNT NAME>"
       azure_storage_access_key = "<AZURE STORAGE ACCESS KEY>"

  If you are using a custom Azure storage domain, azure_storage_domain does not have to be set in the Workhorse configuration. This information is exchanged in an API call between GitLab Rails and Workhorse.

Storj Gateway (SJ)

NOTE: The Storj Gateway does not support multi-threaded copying (see UploadPartCopy in the table). While an implementation is planned, you must disable multi-threaded copying until completion.

The Storj Network provides an S3-compatible API gateway. Use the following configuration example:

gitlab_rails['object_store']['connection'] = {
  'provider' => 'AWS',
  'endpoint' => 'https://gateway.storjshare.io',
  'path_style' => true,
  'region' => 'eu1',
  'aws_access_key_id' => 'ACCESS_KEY',
  'aws_secret_access_key' => 'SECRET_KEY',
  'aws_signature_version' => 2,
  'enable_signature_v4_streaming' => false
}

The signature version must be 2. Using v4 results in a HTTP 411 Length Required error. For more information, see issue #4419.

Hitachi Vantara HCP

NOTE: Connections to HCP may return an error stating SignatureDoesNotMatch - The request signature we calculated does not match the signature you provided. Check your HCP Secret Access key and signing method. In these cases, set the endpoint to the URL of the tenant instead of the namespace, and ensure bucket paths are configured as <namespace_name>/<bucket_name>.

HCP provides an S3-compatible API. Use the following configuration example:

gitlab_rails['object_store']['connection'] = {
  'provider' => 'AWS',
  'endpoint' => 'https://<tenant_endpoint>',
  'path_style' => true,
  'region' => 'eu1',
  'aws_access_key_id' => 'ACCESS_KEY',
  'aws_secret_access_key' => 'SECRET_KEY',
  'aws_signature_version' => 4,
  'enable_signature_v4_streaming' => false
}

# Example of <namespace_name/bucket_name> formatting
gitlab_rails['object_store']['objects']['artifacts']['bucket'] = '<namespace_name>/<bucket_name>'

Full example using the consolidated form and Amazon S3

The following example uses AWS S3 to enable object storage for all supported services:

::Tabs

:::TabTitle Linux package (Omnibus)

1. Edit /etc/gitlab/gitlab.rb and add the following lines, substituting the values you want:

   # Consolidated object storage configuration
   gitlab_rails['object_store']['enabled'] = true
   gitlab_rails['object_store']['proxy_download'] = true
   gitlab_rails['object_store']['connection'] = {
     'provider' => 'AWS',
     'region' => 'eu-central-1',
     'aws_access_key_id' => '<AWS_ACCESS_KEY_ID>',
     'aws_secret_access_key' => '<AWS_SECRET_ACCESS_KEY>'
   }
   # OPTIONAL: The following lines are only needed if server side encryption is required
   gitlab_rails['object_store']['storage_options'] = {
     'server_side_encryption' => '<AES256 or aws:kms>',
     'server_side_encryption_kms_key_id' => '<arn:aws:kms:xxx>'
   }
   gitlab_rails['object_store']['objects']['artifacts']['bucket'] = 'gitlab-artifacts'
   gitlab_rails['object_store']['objects']['external_diffs']['bucket'] = 'gitlab-mr-diffs'
   gitlab_rails['object_store']['objects']['lfs']['bucket'] = 'gitlab-lfs'
   gitlab_rails['object_store']['objects']['uploads']['bucket'] = 'gitlab-uploads'
   gitlab_rails['object_store']['objects']['packages']['bucket'] = 'gitlab-packages'
   gitlab_rails['object_store']['objects']['dependency_proxy']['bucket'] = 'gitlab-dependency-proxy'
   gitlab_rails['object_store']['objects']['terraform_state']['bucket'] = 'gitlab-terraform-state'
   gitlab_rails['object_store']['objects']['ci_secure_files']['bucket'] = 'gitlab-ci-secure-files'
   gitlab_rails['object_store']['objects']['pages']['bucket'] = 'gitlab-pages'

   If you're using AWS IAM profiles, omit the AWS access key and secret access key/value pairs. For example:

   gitlab_rails['object_store']['connection'] = {
     'provider' => 'AWS',
     'region' => 'eu-central-1',
     'use_iam_profile' => true
   }

2. Save the file and reconfigure GitLab:

   sudo gitlab-ctl reconfigure

:::TabTitle Helm chart (Kubernetes)

1. Put the following content in a file named object_storage.yaml to be used as a Kubernetes Secret:

   provider: AWS
   region: us-east-1
   aws_access_key_id: <AWS_ACCESS_KEY_ID>
   aws_secret_access_key: <AWS_SECRET_ACCESS_KEY>

   If you're using AWS IAM profiles, omit the AWS access key and secret access key/value pairs. For example:

   provider: AWS
   region: us-east-1
   use_iam_profile: true

2. Create the Kubernetes Secret:

   kubectl create secret generic -n <namespace> gitlab-object-storage --from-file=connection=object_storage.yaml

3. Export the Helm values:

   helm get values gitlab > gitlab_values.yaml

4. Edit gitlab_values.yaml:

   global:
     appConfig:
       object_store:
         enabled: false
         proxy_download: true
         storage_options: {}
           # server_side_encryption:
           # server_side_encryption_kms_key_id
         connection:
           secret: gitlab-object-storage
       lfs:
         enabled: true
         proxy_download: true
         bucket: gitlab-lfs
         connection: {}
           # secret:
           # key:
       artifacts:
         enabled: true
         proxy_download: true
         bucket: gitlab-artifacts
         connection: {}
           # secret:
           # key:
       uploads:
         enabled: true
         proxy_download: true
         bucket: gitlab-uploads
         connection: {}
           # secret:
           # key:
       packages:
         enabled: true
         proxy_download: true
         bucket: gitlab-packages
         connection: {}
       externalDiffs:
         enabled: true
         when:
         proxy_download: true
         bucket: gitlab-mr-diffs
         connection: {}
       terraformState:
         enabled: true
         bucket: gitlab-terraform-state
         connection: {}
       ciSecureFiles:
         enabled: true
         bucket: gitlab-ci-secure-files
         connection: {}
       dependencyProxy:
         enabled: true
         proxy_download: true
         bucket: gitlab-dependency-proxy
         connection: {}

5. Save the file and apply the new values:

   helm upgrade -f gitlab_values.yaml gitlab gitlab/gitlab

:::TabTitle Docker

1. Edit docker-compose.yml:

   version: "3.6"
   services:
     gitlab:
       environment:
         GITLAB_OMNIBUS_CONFIG: |
           # Consolidated object storage configuration
           gitlab_rails['object_store']['enabled'] = true
           gitlab_rails['object_store']['proxy_download'] = true
           gitlab_rails['object_store']['connection'] = {
             'provider' => 'AWS',
             'region' => 'eu-central-1',
             'aws_access_key_id' => '<AWS_ACCESS_KEY_ID>',
             'aws_secret_access_key' => '<AWS_SECRET_ACCESS_KEY>'
           }
           # OPTIONAL: The following lines are only needed if server side encryption is required
           gitlab_rails['object_store']['storage_options'] = {
             'server_side_encryption' => '<AES256 or aws:kms>',
             'server_side_encryption_kms_key_id' => '<arn:aws:kms:xxx>'
           }
           gitlab_rails['object_store']['objects']['artifacts']['bucket'] = 'gitlab-artifacts'
           gitlab_rails['object_store']['objects']['external_diffs']['bucket'] = 'gitlab-mr-diffs'
           gitlab_rails['object_store']['objects']['lfs']['bucket'] = 'gitlab-lfs'
           gitlab_rails['object_store']['objects']['uploads']['bucket'] = 'gitlab-uploads'
           gitlab_rails['object_store']['objects']['packages']['bucket'] = 'gitlab-packages'
           gitlab_rails['object_store']['objects']['dependency_proxy']['bucket'] = 'gitlab-dependency-proxy'
           gitlab_rails['object_store']['objects']['terraform_state']['bucket'] = 'gitlab-terraform-state'
           gitlab_rails['object_store']['objects']['ci_secure_files']['bucket'] = 'gitlab-ci-secure-files'
           gitlab_rails['object_store']['objects']['pages']['bucket'] = 'gitlab-pages'

   If you're using AWS IAM profiles, omit the AWS access key and secret access key/value pairs. For example:

   gitlab_rails['object_store']['connection'] = {
     'provider' => 'AWS',
     'region' => 'eu-central-1',
     'use_iam_profile' => true
   }

2. Save the file and restart GitLab:

   docker compose up -d

:::TabTitle Self-compiled (source)

1. Edit /home/git/gitlab/config/gitlab.yml and add or amend the following lines:

   production: &base
     object_store:
       enabled: true
       proxy_download: true
       connection:
         provider: AWS
         aws_access_key_id: <AWS_ACCESS_KEY_ID>
         aws_secret_access_key: <AWS_SECRET_ACCESS_KEY>
         region: eu-central-1
       storage_options:
         server_side_encryption: <AES256 or aws:kms>
         server_side_encryption_key_kms_id: <arn:aws:kms:xxx>
       objects:
         artifacts:
           bucket: gitlab-artifacts
         external_diffs:
           bucket: gitlab-mr-diffs
         lfs:
           bucket: gitlab-lfs
         uploads:
           bucket: gitlab-uploads
         packages:
           bucket: gitlab-packages
         dependency_proxy:
           bucket: gitlab-dependency-proxy
         terraform_state:
           bucket: gitlab-terraform-state
         ci_secure_files:
           bucket: gitlab-ci-secure-files
         pages:
           bucket: gitlab-pages

   If you're using AWS IAM profiles, omit the AWS access key and secret access key/value pairs. For example:

   connection:
     provider: AWS
     region: eu-central-1
     use_iam_profile: true

2. Edit /home/git/gitlab-workhorse/config.toml and add or amend the following lines:

   [object_storage]
     provider = "AWS"
   
   [object_storage.s3]
     aws_access_key_id = "<AWS_ACCESS_KEY_ID>"
     aws_secret_access_key = "<AWS_SECRET_ACCESS_KEY>"

   If you're using AWS IAM profiles, omit the AWS access key and secret access key/value pairs. For example:

   [object_storage.s3]
     use_iam_profile = true

3. Save the file and restart GitLab:

   # For systems running systemd
   sudo systemctl restart gitlab.target
   
   # For systems running SysV init
   sudo service gitlab restart

::EndTabs

Migrate to object storage

To migrate existing local data to object storage see the following guides:

• Job artifacts including archived job logs
• LFS objects
• Uploads
• Merge request diffs
• Packages (optional feature)
• Dependency Proxy
• Terraform state files
• Pages content
• Project-level Secure Files

Transition to consolidated form

In storage-specific configuration:

• Object storage configuration for all types of objects such as CI/CD artifacts, LFS files, and upload attachments is configured independently.
• Object store connection parameters such as passwords and endpoint URLs is duplicated for each type.

For example, a Linux package installation might have the following configuration:

# Original object storage configuration
gitlab_rails['artifacts_object_store_enabled'] = true
gitlab_rails['artifacts_object_store_direct_upload'] = true
gitlab_rails['artifacts_object_store_proxy_download'] = true
gitlab_rails['artifacts_object_store_remote_directory'] = 'artifacts'
gitlab_rails['artifacts_object_store_connection'] = { 'provider' => 'AWS', 'aws_access_key_id' => 'access_key', 'aws_secret_access_key' => 'secret' }
gitlab_rails['uploads_object_store_enabled'] = true
gitlab_rails['uploads_object_store_direct_upload'] = true
gitlab_rails['uploads_object_store_proxy_download'] = true
gitlab_rails['uploads_object_store_remote_directory'] = 'uploads'
gitlab_rails['uploads_object_store_connection'] = { 'provider' => 'AWS', 'aws_access_key_id' => 'access_key', 'aws_secret_access_key' => 'secret' }

Although this provides flexibility in that it makes it possible for GitLab to store objects across different cloud providers, it also creates additional complexity and unnecessary redundancy. Since both GitLab Rails and Workhorse components need access to object storage, the consolidated form avoids excessive duplication of credentials.

The consolidated form is used only if all lines from the original form is omitted. To move to the consolidated form, remove the original configuration (for example, artifacts_object_store_enabled, or uploads_object_store_connection)

Migrate objects to a different object storage provider

You may need to migrate GitLab data in object storage to a different object storage provider. The following steps show you how do this using Rclone.

The steps assume you are moving the uploads bucket, but the same process works for other buckets.

Prerequisites:

• Choose the computer to run Rclone on. Depending on how much data you are migrating, Rclone may have to run for a long time so you should avoid using a laptop or desktop computer that can go into power saving. You can use your GitLab server to run Rclone.

1. Install Rclone.

2. Configure Rclone by running the following:

   rclone config

   The configuration process is interactive. Add at least two "remotes": one for the object storage provider your data is currently on (old), and one for the provider you are moving to (new).

3. Verify that you can read the old data. The following example refers to the uploads bucket , but your bucket may have a different name:

   rclone ls old:uploads | head

   This should print a partial list of the objects currently stored in your uploads bucket. If you get an error, or if the list is empty, go back and update your Rclone configuration using rclone config.

4. Perform an initial copy. You do not need to take your GitLab server offline for this step.

   rclone sync -P old:uploads new:uploads

5. After the first sync completes, use the web UI or command-line interface of your new object storage provider to verify that there are objects in the new bucket. If there are none, or if you encounter an error while running rclone sync, check your Rclone configuration and try again.

After you have done at least one successful Rclone copy from the old location to the new location, schedule maintenance and take your GitLab server offline. During your maintenance window you must do two things:

1. Perform a final rclone sync run, knowing that your users cannot add new objects so you do not leave any behind in the old bucket.
2. Update the object storage configuration of your GitLab server to use the new provider for uploads.

Alternatives to file system storage

If you're working to scale out your GitLab implementation, or add fault tolerance and redundancy, you may be looking at removing dependencies on block or network file systems. See the following additional guides:

1. Make sure the git user home directory is on local disk.
2. Configure database lookup of SSH keys to eliminate the need for a shared authorized_keys file.
3. Prevent local disk usage for job logs.
4. Disable Pages local storage.

Troubleshooting

Objects are not included in GitLab backups

As noted in the backup documentation, objects are not included in GitLab backups. You can enable backups with your object storage provider instead.

Use separate buckets

Using separate buckets for each data type is the recommended approach for GitLab. This ensures there are no collisions across the various types of data GitLab stores. Issue 292958 proposes to enable the use of a single bucket.

With Linux package and self-compiled installations, it is possible to split a single real bucket into multiple virtual buckets. If your object storage bucket is called my-gitlab-objects you can configure uploads to go into my-gitlab-objects/uploads, artifacts into my-gitlab-objects/artifacts, etc. The application acts as if these are separate buckets. Use of bucket prefixes may not work correctly with Helm backups.

Helm-based installs require separate buckets to handle backup restorations.

S3 API compatibility issues

Not all S3 providers are fully compatible with the Fog library that GitLab uses. Symptoms include an error in production.log:

411 Length Required

Artifacts always downloaded with filename download

Downloaded artifact filenames are set with the response-content-disposition header in the GetObject request. If the S3 provider does not support this header, the downloaded file is always saved as download.

Proxy Download

Clients can download files in object storage by receiving a pre-signed, time-limited URL, or by GitLab proxying the data from object storage to the client. Downloading files from object storage directly helps reduce the amount of egress traffic GitLab needs to process.

When the files are stored on local block storage or NFS, GitLab has to act as a proxy. This is not the default behavior with object storage.

The proxy_download setting controls this behavior: the default is generally false. Verify this in the documentation for each use case. Set it to true if you want GitLab to proxy the files.

When not proxying files, GitLab returns an HTTP 302 redirect with a pre-signed, time-limited object storage URL. This can result in some of the following problems:

• If GitLab is using non-secure HTTP to access the object storage, clients may generate https->http downgrade errors and refuse to process the redirect. The solution to this is for GitLab to use HTTPS. LFS, for example, generates this error:

  LFS: lfsapi/client: refusing insecure redirect, https->http

• Clients need to trust the certificate authority that issued the object storage certificate, or may return common TLS errors such as:

  x509: certificate signed by unknown authority

• Clients need network access to the object storage. Network firewalls could block access. Errors that might result if this access is not in place include:

  Received status code 403 from server: Forbidden

• Object storage buckets need to allow Cross-Origin Resource Sharing (CORS) access from the URL of the GitLab instance. Attempting to load a PDF in the repository page may show the following error:

  An error occurred while loading the file. Please try again later.

  See the LFS documentation for more details.

Additionally for a short time period users could share pre-signed, time-limited object storage URLs with others without authentication. Also bandwidth charges may be incurred between the object storage provider and the client.

ETag mismatch

Using the default GitLab settings, some object storage back-ends such as MinIO and Alibaba might generate ETag mismatch errors.

Amazon S3 encryption

If you are seeing this ETag mismatch error with Amazon Web Services S3, it's likely this is due to encryption settings on your bucket. To fix this issue, you have two options:

• Use the consolidated form.
• Use Amazon instance profiles.

The first option is recommended for MinIO. Otherwise, the workaround for MinIO is to use the --compat parameter on the server.

Without the consolidated form or instance profiles enabled, GitLab Workhorse uploads files to S3 using pre-signed URLs that do not have a Content-MD5 HTTP header computed for them. To ensure data is not corrupted, Workhorse checks that the MD5 hash of the data sent equals the ETag header returned from the S3 server. When encryption is enabled, this is not the case, which causes Workhorse to report an ETag mismatch error during an upload.

When the consolidated form is:

• Used with an S3-compatible object storage or an instance profile, Workhorse uses its internal S3 client which has S3 credentials so that it can compute the Content-MD5 header. This eliminates the need to compare ETag headers returned from the S3 server.
• Not used with an S3-compatible object storage, Workhorse falls back to using pre-signed URLs.

Google Cloud Storage encryption

• Introduced in GitLab 16.11.

ETag mismatch errors occur also in Google Cloud Storage (GCS) when enabling data encryption with customer-managed encryption keys (CMEK).

To use CMEK, use the consolidated form.

Multi-threaded copying

GitLab uses the S3 Upload Part Copy API to accelerate the copying of files within a bucket. Ceph S3 prior to Kraken 11.0.2 does not support this and returns a 404 error when files are copied during the upload process.

The feature can be disabled using the :s3_multithreaded_uploads feature flag. To disable the feature, ask a GitLab administrator with Rails console access to run the following command:

Feature.disable(:s3_multithreaded_uploads)

Manual testing through Rails Console

In some situations, it may be helpful to test object storage settings using the Rails Console. The following example tests a given set of connection settings, attempts to write a test object, and finally read it.

1. Start a Rails console.

2. Set up the object storage connection, using the same parameters you set up in /etc/gitlab/gitlab.rb, in the following example format:

   Example connection using access keys:

   connection = Fog::Storage.new(
     {
       provider: 'AWS',
       region: `eu-central-1`,
       aws_access_key_id: '<AWS_ACCESS_KEY_ID>',
       aws_secret_access_key: '<AWS_SECRET_ACCESS_KEY>'
     }
   )

   Example connection using AWS IAM Profiles:

   connection = Fog::Storage.new(
     {
       provider: 'AWS',
       use_iam_profile: true,
       region: 'us-east-1'
     }
   )

3. Specify the bucket name to test against, write, and finally read a test file.

   dir = connection.directories.new(key: '<bucket-name-here>')
   f = dir.files.create(key: 'test.txt', body: 'test')
   pp f
   pp dir.files.head('test.txt')