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Google Cloud Storage repository

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Google Cloud Storage repository

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You can use the Google Cloud Storage service as a repository for Snapshot/Restore.

Getting started

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This repository type uses the Google Cloud Java Client for Storage to connect to the Storage service. If you are using Google Cloud Storage for the first time, you must connect to the Google Cloud Platform Console and create a new project. After your project is created, you must enable the Cloud Storage Service for your project.

Creating a bucket

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The Google Cloud Storage service uses the concept of a bucket as a container for all the data. Buckets are usually created using the Google Cloud Platform Console. This repository type does not automatically create buckets.

To create a new bucket:

Connect to the Google Cloud Platform Console.
Select your project.
Go to the Storage Browser.
Click the Create Bucket button.
Enter the name of the new bucket.
Select a storage class.
Select a location.
Click the Create button.

For more detailed instructions, see the Google Cloud documentation.

Service authentication

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The repository must authenticate the requests it makes to the Google Cloud Storage service. It is common for Google client libraries to employ a strategy named application default credentials. However, that strategy is only partially supported by Elasticsearch. The repository operates under the Elasticsearch process, which runs with the security manager enabled. The security manager obstructs the "automatic" credential discovery when the environment variable GOOGLE_APPLICATION_CREDENTIALS is used to point to a local file on disk. It can, however, retrieve the service account that is attached to the resource that is running Elasticsearch, or fall back to the default service account that Compute Engine, Kubernetes Engine or App Engine provide. Alternatively, you must configure service account credentials if you are using an environment that does not support automatic credential discovery.

Using a service account

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You have to obtain and provide service account credentials manually.

For detailed information about generating JSON service account files, see the Google Cloud documentation. Note that the PKCS12 format is not supported by this repository type.

Here is a summary of the steps:

Connect to the Google Cloud Platform Console.
Select your project.
Select the Service Accounts tab.
Click Create service account.
After the account is created, select it and go to Keys.
Select Add Key and then Create new key.
Select Key Type JSON as P12 is unsupported.

A JSON service account file looks like this:

{
  "type": "service_account",
  "project_id": "your-project-id",
  "private_key_id": "...",
  "private_key": "-----BEGIN PRIVATE KEY-----\n...\n-----END PRIVATE KEY-----\n",
  "client_email": "service-account-for-your-repository@your-project-id.iam.gserviceaccount.com",
  "client_id": "...",
  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
  "token_uri": "https://accounts.google.com/o/oauth2/token",
  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/your-bucket@your-project-id.iam.gserviceaccount.com"
}

To provide this file to the repository, it must be stored in the Elasticsearch keystore. You must add a file setting with the name gcs.client.NAME.credentials_file using the add-file subcommand. NAME is the name of the client configuration for the repository. The implicit client name is default, but a different client name can be specified in the repository settings with the client key.

Passing the file path via the GOOGLE_APPLICATION_CREDENTIALS environment variable is not supported.

For example, if you added a gcs.client.my_alternate_client.credentials_file setting in the keystore, you can configure a repository to use those credentials like this:

PUT _snapshot/my_gcs_repository
{
  "type": "gcs",
  "settings": {
    "bucket": "my_bucket",
    "client": "my_alternate_client"
  }
}

The credentials_file settings are reloadable. After you reload the settings, the internal gcs clients, which are used to transfer the snapshot contents, utilize the latest settings from the keystore.

Snapshot or restore jobs that are in progress are not preempted by a reload of the client’s credentials_file settings. They complete using the client as it was built when the operation started.

Client settings

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The client used to connect to Google Cloud Storage has a number of settings available. Client setting names are of the form gcs.client.CLIENT_NAME.SETTING_NAME and are specified inside elasticsearch.yml. The default client name looked up by a gcs repository is called default, but can be customized with the repository setting client.

For example:

PUT _snapshot/my_gcs_repository
{
  "type": "gcs",
  "settings": {
    "bucket": "my_bucket",
    "client": "my_alternate_client"
  }
}

Some settings are sensitive and must be stored in the Elasticsearch keystore. This is the case for the service account file:

bin/elasticsearch-keystore add-file gcs.client.default.credentials_file /path/service-account.json

The following are the available client settings. Those that must be stored in the keystore are marked as Secure.

credentials_file (Secure, reloadable): The service account file that is used to authenticate to the Google Cloud Storage service.
endpoint: The Google Cloud Storage service endpoint to connect to. This will be automatically determined by the Google Cloud Storage client but can be specified explicitly.
connect_timeout: The timeout to establish a connection to the Google Cloud Storage service. The value should specify the unit. For example, a value of 5s specifies a 5 second timeout. The value of -1 corresponds to an infinite timeout. The default value is 20 seconds.
read_timeout: The timeout to read data from an established connection. The value should specify the unit. For example, a value of 5s specifies a 5 second timeout. The value of -1 corresponds to an infinite timeout. The default value is 20 seconds.
application_name: Name used by the client when it uses the Google Cloud Storage service. Setting a custom name can be useful to authenticate your cluster when requests statistics are logged in the Google Cloud Platform. Default to repository-gcs
project_id: The Google Cloud project id. This will be automatically inferred from the credentials file but can be specified explicitly. For example, it can be used to switch between projects when the same credentials are usable for both the production and the development projects.
proxy.host: Host name of a proxy to connect to the Google Cloud Storage through.
proxy.port: Port of a proxy to connect to the Google Cloud Storage through.
proxy.type: Proxy type for the client. Supported values are direct (no proxy), http, and socks. Defaults to direct.

Repository settings

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The gcs repository type supports a number of settings to customize how data is stored in Google Cloud Storage.

These can be specified when creating the repository. For example:

PUT _snapshot/my_gcs_repository
{
  "type": "gcs",
  "settings": {
    "bucket": "my_other_bucket",
    "base_path": "dev"
  }
}

The following settings are supported:

bucket: The name of the bucket to be used for snapshots. (Mandatory)
client: The name of the client to use to connect to Google Cloud Storage. Defaults to default.
base_path: Specifies the path within bucket to repository data. Defaults to the root of the bucket.

Don’t set base_path when configuring a snapshot repository for Elastic Cloud Enterprise. Elastic Cloud Enterprise automatically generates the base_path for each deployment so that multiple deployments may share the same bucket.
chunk_size: Big files can be broken down into multiple smaller blobs in the blob store during snapshotting. It is not recommended to change this value from its default unless there is an explicit reason for limiting the size of blobs in the repository. Setting a value lower than the default can result in an increased number of API calls to the Google Cloud Storage Service during snapshot create as well as restore operations compared to using the default value and thus make both operations slower as well as more costly. Specify the chunk size as a value and unit, for example: 10MB, 5KB, 500B. Defaults to the maximum size of a blob in the Google Cloud Storage Service which is 5TB.
compress: When set to true metadata files are stored in compressed format. This setting doesn’t affect index files that are already compressed by default. Defaults to true.
max_restore_bytes_per_sec: (Optional, byte value) Maximum snapshot restore rate per node. Defaults to unlimited. Note that restores are also throttled through recovery settings.
max_snapshot_bytes_per_sec: (Optional, byte value) Maximum snapshot creation rate per node. Defaults to 40mb per second.

readonly

(Optional, Boolean) If true, the repository is read-only. The cluster can retrieve and restore snapshots from the repository but not write to the repository or create snapshots in it.

Only a cluster with write access can create snapshots in the repository. All other clusters connected to the repository should have the readonly parameter set to true.

If false, the cluster can write to the repository and create snapshots in it. Defaults to false.

If you register the same snapshot repository with multiple clusters, only one cluster should have write access to the repository. Having multiple clusters write to the repository at the same time risks corrupting the contents of the repository.

application_name

[6.3.0] Deprecated in 6.3.0. This setting is now defined in the client settings. Name used by the client when it uses the Google Cloud Storage service.

Recommended bucket permission

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The service account used to access the bucket must have the "Writer" access to the bucket:

Connect to the Google Cloud Platform Console.
Select your project.
Go to the Storage Browser.
Select the bucket and "Edit bucket permission".
The service account must be configured as a "User" with "Writer" access.

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