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[DOC] Repository GCS ADC not supported (#33238)
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Make it clear that automatic default credentials (ADC)
is not supported for the repository-gcs plugin.
"Service Account" method is the only alternative
to authn requests to Google Cloud Storage.
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@albertzaharovits
albertzaharovits authored Aug 30, 2018
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139 changes: 70 additions & 69 deletions docs/plugins/repository-gcs.asciidoc
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Expand Up @@ -10,71 +10,66 @@ include::install_remove.asciidoc[]
[[repository-gcs-usage]]
==== Getting started

The plugin uses the https://cloud.google.com/storage/docs/json_api/[Google Cloud Storage JSON API] (v1)
to connect to the Storage service. If this is the first time you use Google Cloud Storage, you first
need to connect to the https://console.cloud.google.com/[Google Cloud Platform Console] and create a new
project. Once your project is created, you must enable the Cloud Storage Service for your project.
The plugin uses the https://github.com/GoogleCloudPlatform/google-cloud-java/tree/master/google-cloud-clients/google-cloud-storage[Google Cloud Java Client for Storage]
to connect to the Storage service. If you are using
https://cloud.google.com/storage/[Google Cloud Storage] for the first time, you
must connect to the https://console.cloud.google.com/[Google Cloud Platform Console]
and create a new project. After your project is created, you must enable the
Cloud Storage Service for your project.

[[repository-gcs-creating-bucket]]
===== Creating a Bucket

Google Cloud Storage service uses the concept of https://cloud.google.com/storage/docs/key-terms[Bucket]
as a container for all the data. Buckets are usually created using the
https://console.cloud.google.com/[Google Cloud Platform Console]. The plugin will not automatically
create buckets.
The Google Cloud Storage service uses the concept of a
https://cloud.google.com/storage/docs/key-terms[bucket] as a container for all
the data. Buckets are usually created using the
https://console.cloud.google.com/[Google Cloud Platform Console]. The plugin
does not automatically create buckets.

To create a new bucket:

1. Connect to the https://console.cloud.google.com/[Google Cloud Platform Console]
2. Select your project
3. Go to the https://console.cloud.google.com/storage/browser[Storage Browser]
4. Click the "Create Bucket" button
5. Enter the name of the new bucket
6. Select a storage class
7. Select a location
8. Click the "Create" button
1. Connect to the https://console.cloud.google.com/[Google Cloud Platform Console].
2. Select your project.
3. Go to the https://console.cloud.google.com/storage/browser[Storage Browser].
4. Click the *Create Bucket* button.
5. Enter the name of the new bucket.
6. Select a storage class.
7. Select a location.
8. Click the *Create* button.

The bucket should now be created.
For more detailed instructions, see the
https://cloud.google.com/storage/docs/quickstart-console#create_a_bucket[Google Cloud documentation].

[[repository-gcs-service-authentication]]
===== Service Authentication

The plugin supports two authentication modes:

* The built-in <<repository-gcs-using-compute-engine, Compute Engine authentication>>. This mode is
recommended if your Elasticsearch node is running on a Compute Engine virtual machine.

* Specifying <<repository-gcs-using-service-account, Service Account>> credentials.

[[repository-gcs-using-compute-engine]]
===== Using Compute Engine
When running on Compute Engine, the plugin use Google's built-in authentication mechanism to
authenticate on the Storage service. Compute Engine virtual machines are usually associated to a
default service account. This service account can be found in the VM instance details in the
https://console.cloud.google.com/compute/[Compute Engine console].

This is the default authentication mode and requires no configuration.

NOTE: The Compute Engine VM must be allowed to use the Storage service. This can be done only at VM
creation time, when "Storage" access can be configured to "Read/Write" permission. Check your
instance details at the section "Cloud API access scopes".
The plugin must authenticate the requests it makes to the Google Cloud Storage
service. It is common for Google client libraries to employ a strategy named https://cloud.google.com/docs/authentication/production#providing_credentials_to_your_application[application default credentials].
However, that strategy is **not** supported for use with Elasticsearch. The
plugin operates under the Elasticsearch process, which runs with the security
manager enabled. The security manager obstructs the "automatic" credential discovery.
Therefore, you must configure <<repository-gcs-using-service-account,service account>>
credentials even if you are using an environment that does not normally require
this configuration (such as Compute Engine, Kubernetes Engine or App Engine).

[[repository-gcs-using-service-account]]
===== Using a Service Account
If your Elasticsearch node is not running on Compute Engine, or if you don't want to use Google's
built-in authentication mechanism, you can authenticate on the Storage service using a
https://cloud.google.com/iam/docs/overview#service_account[Service Account] file.
You have to obtain and provide https://cloud.google.com/iam/docs/overview#service_account[service account credentials]
manually.

For detailed information about generating JSON service account files, see the https://cloud.google.com/storage/docs/authentication?hl=en#service_accounts[Google Cloud documentation].
Note that the PKCS12 format is not supported by this plugin.

To create a service account file:
Here is a summary of the steps:

1. Connect to the https://console.cloud.google.com/[Google Cloud Platform Console]
2. Select your project
3. Got to the https://console.cloud.google.com/permissions[Permission] tab
4. Select the https://console.cloud.google.com/permissions/serviceaccounts[Service Accounts] tab
5. Click on "Create service account"
6. Once created, select the new service account and download a JSON key file
1. Connect to the https://console.cloud.google.com/[Google Cloud Platform Console].
2. Select your project.
3. Got to the https://console.cloud.google.com/permissions[Permission] tab.
4. Select the https://console.cloud.google.com/permissions/serviceaccounts[Service Accounts] tab.
5. Click *Create service account*.
6. After the account is created, select it and download a JSON key file.

A service account file looks like this:
A JSON service account file looks like this:

[source,js]
----
Expand All @@ -84,19 +79,26 @@ A service account file looks like this:
"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": "..."
"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"
}
----
// NOTCONSOLE

This file must be stored in the {ref}/secure-settings.html[elasticsearch keystore], under a setting name
of the form `gcs.client.NAME.credentials_file`, where `NAME` is the name of the client configuration.
The default client name is `default`, but a different client name can be specified in repository
settings using `client`.
To provide this file to the plugin, it must be stored in the {ref}/secure-settings.html[Elasticsearch keystore]. You must add a setting name of the form `gcs.client.NAME.credentials_file`, where `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.

For example, if specifying the credentials file in the keystore under
`gcs.client.my_alternate_client.credentials_file`, you can configure a repository to use these
credentials like this:
NOTE: 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:

[source,js]
----
Expand All @@ -113,19 +115,18 @@ PUT _snapshot/my_gcs_repository
// TEST[skip:we don't have gcs setup while testing this]

The `credentials_file` settings are {ref}/secure-settings.html#reloadable-secure-settings[reloadable].
After you reload the settings, the internal `gcs` clients, used to transfer the
snapshot contents, will utilize the latest settings from the keystore.

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

NOTE: In progress snapshot/restore jobs will not be preempted by a *reload*
of the client's `credentials_file` settings. They will complete using the client
as it was built when the operation started.
NOTE: 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.

[[repository-gcs-client]]
==== Client Settings

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 specified
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`.

Expand All @@ -146,7 +147,7 @@ PUT _snapshot/my_gcs_repository
// TEST[skip:we don't have gcs setup while testing this]

Some settings are sensitive and must be stored in the
{ref}/secure-settings.html[elasticsearch keystore]. This is the case for the service account file:
{ref}/secure-settings.html[Elasticsearch keystore]. This is the case for the service account file:

[source,sh]
----
Expand Down Expand Up @@ -185,7 +186,7 @@ are marked as `Secure`.

`project_id`::

The Google Cloud project id. This will be automatically infered from the credentials file but
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.

Expand Down Expand Up @@ -248,8 +249,8 @@ The following settings are supported:

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

1. Connect to the https://console.cloud.google.com/[Google Cloud Platform Console]
2. Select your project
3. Got to the https://console.cloud.google.com/storage/browser[Storage Browser]
4. Select the bucket and "Edit bucket permission"
5. The service account must be configured as a "User" with "Writer" access
1. Connect to the https://console.cloud.google.com/[Google Cloud Platform Console].
2. Select your project.
3. Got to the https://console.cloud.google.com/storage/browser[Storage Browser].
4. Select the bucket and "Edit bucket permission".
5. The service account must be configured as a "User" with "Writer" access.

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