Learn how to configure Google Distributed Cloud to use OpenID Connect (OIDC) for authentication to user clusters. This page covers the process in general to help you understand how to configure any OpenID provider.
For an overview of the Google Distributed Cloud authentication flow, see Authentication. To learn how to configure OIDC with other OpenID providers, see the following resources:
- Authenticating with OIDC and Active Directory Federation Services (AD FS)
- Authenticating with OIDC and Google
Google Distributed Cloud supports OIDC as one of the authentication mechanisms for interacting with a user cluster's Kubernetes API server. With OIDC, you can manage access to Kubernetes clusters by using the standard procedures in your organization for creating, enabling, and disabling user accounts.
There are two ways that users can authorize their accounts:
Use the Google Cloud CLI to initiate the OIDC flow and obtain user authorization through a browser-based consent page.
Use the Google Cloud console to initiate the OIDC authentication flow.
Before you begin
This topic assumes that you are familiar with the following authentication and OpenID concepts:
Headless systems are unsupported. A browser-based authentication flow is used to prompt you for consent and authorize your user account.
To authenticate through the Google Cloud console, each cluster that you want to configure for OIDC authentication must be registered with Google Cloud.
Personas
This topic refers to three personas:
Organization administrator. This person chooses an OpenID provider and registers client applications with the provider.
Cluster administrator. This person creates one or more user clusters and creates authentication configuration files for developers who use the clusters.
Developer. This person runs workloads on one or more clusters and uses OIDC to authenticate.
Choosing an OpenID provider
This section is for organization administrators.
You can use any OpenID provider of your choice. For a list of certified providers, see OpenID Certification.
For the following OpenID providers, see specific configuration steps in the following resources:
Creating redirect URLs
This section is for organization administrators.
You must create redirect URLs for both the gcloud CLI and the Google Cloud console that the OpenID provider can use to return ID tokens.
gcloud CLI redirect URL
The Google Cloud CLI is installed on each developer's local machine. You can specify a port number greater than 1024 to use for the redirect URL:
http://localhost:PORT/callback
Replace PORT
with your port number.
When you configure your OpenID provider, specify
http://localhost:PORT/callback
as one of your redirect
URLs. How you do this depends on your provider.
Google Cloud console redirect URL
The redirect URL for the Google Cloud console is:
https://console.cloud.google.com/kubernetes/oidc
When you configure your OIDC provider, specify
https://console.cloud.google.com/kubernetes/oidc
as one of your redirect URLs.
How you do this depends on your provider.
Registering your client applications with the OpenID provider
This section is for organization administrators.
Before your developers can use the gcloud CLI or the Google Cloud console with your OpenID provider, you need to register those two clients with the OpenID provider. Registration includes these steps:
Learn the provider's issuer URI. This is where the gcloud CLI or the Google Cloud console sends authentication requests.
Give the provider the redirect URL for the gcloud CLI.
Give the provider the redirect URL for the Google Cloud console. This is https://console.cloud.google.com/kubernetes/oidc.
Establish a single client ID. This is the ID that the provider uses to identify both the gcloud CLI and the Google Cloud console.
Establish a single client secret. The gcloud CLI and the Google Cloud console both use this secret to authenticate to the OpenID provider.
Establish a custom scope that the gcloud CLI or the Google Cloud console can use to request the user's security groups.
Establish a custom claim name that the provider will use to return the user's security groups.
How you perform these steps depends on your OpenID provider.
Configuring oidc
on Google Distributed Cloud clusters
This section is for cluster administrators.
To configure OIDC authentication, you need to configure your user cluster's
ClientConfig CRD with authentication details for a cluster. To do this, edit the KRM default object of type clientconfig
in the kube-public
namespace.
kubectl --kubeconfig USER_CLUSTER_KUBECONFIG -n kube-public edit clientconfig default
Details from the ClientConfig CRD are used to configure OIDC for both the Google Cloud console and the Authentication plugin for GKE Enterprise. The configuration includes the following OIDC information.
authentication: - name: NAME_STRING oidc: certificateAuthorityData: CERTIFICATE_STRING clientID: CLIENT_ID clientSecret: CLIENT_SECRET cloudConsoleRedirectURI: "http://console.cloud.google.com/kubernetes/oidc" deployCloudConsoleProxy: PROXY_BOOLEAN extraParams: EXTRA_PARAMS groupsClaim: GROUPS_CLAIM groupPrefix: GROUP_PREFIX issuerURI: ISSUER_URI kubectlRedirectURI: KUBECTL_REDIRECT_URI scopes: SCOPES userClaim: USER_CLAIM userPrefix: USER_PREFIX proxy: PROXY_URL
The following table describes the fields of the ClientConfig CRD oidc
object.
Field | Required | Description | Format |
---|---|---|---|
name | yes | The name of the OIDC configuration to create. | String |
certificateAuthorityData | No | A Example: |
String |
clientID | Yes | ID for the client application that makes authentication requests to the OpenID provider. | String |
clientSecret | No | Shared secret between the OIDC client application and the OIDC provider. | String |
extraParams | No |
Additional key-value parameters to send to the OpenID provider. If you are
authorizing a group, pass in If your authorization server prompts for consent for authentication with
Microsoft Azure and Okta, set |
Comma-delimited list |
groupsClaim | No | JWT claim that the provider uses to return your security groups. | String |
groupPrefix | No | Prefix prepended to group claims to prevent clashes with existing names.
For example, if you have two groups named foobar , add a prefix
gid- . The resulting group is gid-foobar . |
String |
issuerURI | Yes | URL where authorization requests are sent to your OpenID, such as
https://example.com/adfs . The Kubernetes API server uses this URL
to discover public keys for verifying tokens. The URI must use HTTPS. |
URL String |
kubectlRedirectURI | Yes | The redirect URL that kubectl uses for authorization. |
URL String |
scopes | Yes | Additional scopes to send to the OpenID provider. Microsoft Azure and Okta
require the offline_access scope. |
Comma-delimited list |
userClaim | No | JWT claim to use as the username. You can choose other claims, such as email or name, depending on the OpenID provider. However, claims other than email are prefixed with the issuer URL to prevent naming clashes. | String |
userPrefix | No | Prefix prepended to username claims to prevent clashes with existing names. | String |
proxy | No | Proxy server to use for the auth method, if applicable.
For example: http://user:password@10.10.10.10:8888 |
String |
Example: Authorizing users and groups
Many providers encode user-identifying properties, such as email and user IDs, in a token. However, these properties have implicit risks for authentication policies:
User IDs can make policies difficult to read and audit.
Emails can create both an availability risk (if a user changes their primary email) and potentially a security risk (if an email can be re-assigned).
Therefore, it's a best practice to use group policies because a group ID can be both persistent and easier to audit.
Suppose that your provider creates identity tokens that include the following fields:
{ 'iss': 'https://server.example.com' 'sub': 'u98523-4509823' 'groupList': ['developers@example.corp', 'us-east1-cluster-admins@example.corp'] ... }
Given this token format, you would populate your configuration file's
oidc
specification like the following:
issuerURL: 'https://server.example.com' userClaim: 'sub' usernamePrefix: 'uid-' groupsClaim: 'groupList' groupPrefix: 'gid-' extraParams: 'resource=token-groups-claim' ...
After you create the user cluster, you could then use Kubernetes
role-based access control (RBAC) to grant privileged access to the authenticated
users. For example, you could create a ClusterRole
that grants its users
read-only access to the cluster's Secrets, and create a ClusterRoleBinding
resource to bind the role to the authenticated group.
ClusterRole
apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRole metadata: name: secret-reader rules: - apiGroups: [""] # The resource type for which access is granted resources: ["secrets"] # The permissions granted by the ClusterRole verbs: ["get", "watch", "list"]
ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: name: read-secrets-admins subjects: # Allows anyone in the "us-east1-cluster-admins" group to # read Secrets in any namespace within this cluster. - kind: Group name: gid-us-east1-cluster-admins # Name is case-sensitive apiGroup: rbac.authorization.k8s.io # Allows this specific user to read Secrets in any # namespace within this cluster - kind: User name: uid-u98523-4509823 apiGroup: rbac.authorization.k8s.io roleRef: kind: ClusterRole name: secret-reader apiGroup: rbac.authorization.k8s.io
Creating and distributing the authentication configuration file
This section is for cluster administrators.
After you create a user cluster, you create an authentication configuration file for that cluster. You can configure multiple clusters in a single authentication configuration file. You must provide each authentication configuration file to the users who want to authenticate with each of those clusters.
Creating the authentication configuration file
To create the authentication configuration file in
the current directory, run the following gkectl
command:
gkectl create-login-config --kubeconfig USER_CLUSTER_KUBECONFIG
Replace USER_CLUSTER_KUBECONFIG
with the path of your user cluster's
kubeconfig
file. When you ran gkectl create cluster
to create your user
cluster, your
kubeconfig
file
was created.
Result: Your authentication configuration file, named
kubectl-anthos-config.yaml
, is created in the current directory.
Adding multiple clusters to the authentication configuration file
You can store the authentication configuration details for multiple clusters within a single authentication configuration file.
You can use the following command to merge additional user cluster authentication details into an existing authentication configuration file. Given an existing authentication configuration file, you can either merge or combine additional user cluster authentication details:
- Merge the additional user cluster authentication details into that existing authentication configuration file.
- Combine the additional user cluster authentication details into a new file.
For example, you might need to manage both the anthos-config-1cluster.yaml
and anthos-config-3clusters.yaml
authentication configuration files to
accommodate the access needs of the multiple user groups in your organization.
To add additional user clusters to your existing authentication configuration file:
Ensure that each cluster has a unique name. If your clusters have the same names, you cannot combine them into the same authentication configuration file. Note that after a cluster is created, that cluster cannot be renamed.
Run the following
gkectl
command to merge or combine configuration details:gkectl create-login-config --kubeconfig USER_CLUSTER_KUBECONFIG \ --merge-from IN_AUTH_CONFIG_FILE --output OUT_AUTH_CONFIG_FILE
Replace the following:
USER_CLUSTER_KUBECONFIG
specifies thekubeconfig
file of the user cluster that you want to add.IN_AUTH_CONFIG_FILE
specifies the path of the existing authentication configuration file that you want to merge with the additional cluster information.OUT_AUTH_CONFIG_FILE
specifies the path of the file where you want to store the merged authentication configuration:- Specify the same file as
IN_AUTH_CONFIG_FILE
to merge the additional cluster information into that existing file. - Specify a new path and filename to combine the authentication configuration details into a new file.
- Specify the same file as
Distributing the authentication configuration file
To enable your users to authenticate against your user clusters, you must provide them with access to one or more of the authentication configuration files that you created. Note that the following steps use the default file name and the location that are expected by the gcloud CLI. For information about using alternate file names and locations, see Custom configuration.
Consider distributing the authentication configuration files by:
Hosting the file at an accessible URL. If you include the
--login-config
flag in thegcloud anthos auth login
command, the gcloud CLI obtains the authentication configuration file from that location.Consider hosting the file on a secure host. See the
--login-config-cert
flag of the gcloud CLI for more information about using PEM certificates for secure HTTPS access.Manually providing the file to each user. After users download the file, you must instruct them about how to store the file in the default location and with the default filename that the gcloud CLI expects.
For example, users can run the following commands to store the authentication configuration file with the default
kubectl-anthos-config.yaml
filename and in the default location:Linux
mkdir -p $HOME/.config/google/anthos/ cp AUTH_CONFIG_FILE $HOME/.config/google/anthos/kubectl-anthos-config.yaml
where
AUTH_CONFIG_FILE
is the name of your authentication configuration file. For examplekubectl-anthos-config.yaml
.macOS
mkdir -p $HOME/Library/Preferences/google/anthos/ cp AUTH_CONFIG_FILE $HOME/Library/Preferences/google/anthos/kubectl-anthos-config.yaml
where
AUTH_CONFIG_FILE
is the name of your authentication configuration file. For examplekubectl-anthos-config.yaml
.Windows
md "%APPDATA%\google\anthos" copy AUTH_CONFIG_FILE "%APPDATA%\google\anthos\kubectl-anthos-config.yaml"
where
AUTH_CONFIG_FILE
is the name of your authentication configuration file. For examplekubectl-anthos-config.yaml
.Using your internal tools to push the authentication configuration file onto each user's machine. For example, you could use your tooling to push files using the default
kubectl-anthos-config.yaml
filename into their default locations on each user's machine:Linux
$HOME/.config/google/anthos/kubectl-anthos-config.yaml
macOS
$HOME/Library/Preferences/google/anthos/kubectl-anthos-config.yaml
Windows
%APPDATA%\google\anthos\kubectl-anthos-config.yaml
Custom configuration
The gcloud CLI expects the authentication configuration file to be stored in
the default location and with the default filename kubectl-anthos-config.yaml
as mentioned in the prior section. However, you have the option to rename or
store your authentication configuration file in an alternate location. If the
file's name and location differ from the default, you must append the
--login-config
flag to each command that you run when you authenticate with
the cluster. The extra command flag passes in the custom path and filename.
To learn more about the command flag, see
Authenticating through the gcloud CLI.
Installing the gcloud CLI
This section is for both cluster administrators and developers.
Each developer or user who needs to authenticate with a cluster, must install
Google Cloud CLI on their own machine. The Anthos
authentication commands have been integrated into the gcloud CLI as the
anthos-auth
component.
If you have an old version of "Anthos Plugin for Kubectl", you must uninstall that plugin before installing the gcloud CLI and
anthos-auth
component.If you have an existing version of the gcloud CLI, install the latest version and the
anthos-auth
component.
Removing old plugins
You must uninstall the old plugin before you can use the anthos-auth
component of gcloud CLI. You can check whether one of the past kubectl
based plugins exists on your machine by running the following command:
kubectl anthos version
If the command responds with
Error: unknown command "anthos" for "kubectl"
, no plugin was found and you can skip to the next section.If a
1.0beta
version of the plugin was found, you must locate the plugin binary and delete it. Run the following command to list the location and then use that location to remove the binary from your machine:kubectl plugin list
Installing gcloud CLI and the gcloud CLI
To install the gcloud CLI you must first first install gcloud CLI:
Install gcloud CLI but skip the
gcloud init
command.Run the following commands to install the
anthos-auth
component:gcloud components update gcloud components install anthos-auth
Verify that the gcloud CLI was installed successfully by running either of the following commands:
gcloud anthos auth gcloud anthos auth login
Result: Each command should respond with details about the required arguments and available options.
Obtaining the authentication configuration file
This section is for developers.
Your administrator is responsible for creating your authentication configuration file and then providing it to you. For more details, see Distributing the authentication configuration file.
By default, the gcloud CLI uses a default filename and storage location for
your authentication configuration file. If you were manually provided the file
and need to save it on your machine, use the defaults to simplify your
gcloud
authentication commands.
Use the following commands to copy the authentication configuration file to the default location:
Linux
mkdir -p $HOME/.config/google/anthos/ cp AUTH_CONFIG_FILE $HOME/.config/google/anthos/kubectl-anthos-config.yaml
where AUTH_CONFIG_FILE
is the name of your authentication
configuration file. For example kubectl-anthos-config.yaml
.
macOS
mkdir -p $HOME/Library/Preferences/google/anthos/ cp AUTH_CONFIG_FILE $HOME/Library/Preferences/google/anthos/kubectl-anthos-config.yaml
where AUTH_CONFIG_FILE
is the name of your authentication
configuration file. For example kubectl-anthos-config.yaml
.
Windows
md "%APPDATA%\google\anthos" copy AUTH_CONFIG_FILE "%APPDATA%\google\anthos\kubectl-anthos-config.yaml"
where AUTH_CONFIG_FILE
is the name of your authentication
configuration file. For example kubectl-anthos-config.yaml
.
If you choose to use a different filename or location, you have the option to
include the --login-config
flag with each of your authentication requests.
See the following section for details about using the gcloud anthos auth login
command.
Authenticating with user clusters
This section is for developers.
Now that gcloud CLI is installed on your machine and the authentication configuration file has been provided to you by your administrator, you can use either the gcloud CLI or the Google Cloud console to authenticate with your clusters.
Authenticating through the gcloud CLI
Run gcloud
commands to authenticate with your clusters:
Run the
gcloud anthos auth login
command to initiate the authentication flow:gcloud anthos auth login \ --cluster CLUSTER_NAME \ --user USER_NAME \ --login-config AUTH_CONFIG_FILE_PATH \ --login-config-cert CA_CERT_PEM_FILE \ --kubeconfig USER_CLUSTER_KUBECONFIG
where:
CLUSTER_NAME
(optional) specifies the name of your user cluster. If this flag is omitted, you are prompted to choose from the user clusters that are specified in your authentication configuration file.USER_NAME
(optional) specifies the username for the credentials stored in thekubeconfig
file. The default value is
.CLUSTER_NAME
-anthos-default-userAUTH_CONFIG_FILE_PATH
(optional) specifies the custom path or URL to where your authentication configuration file is stored or hosted. You can omit this parameter, if the file is in the default location. Example:--login-config /path/to/custom/authentication-config.yaml
CA_CERT_PEM_FILE
(optional) specifies the path to a PEM certificate file from your CA. If your authentication configuration file is hosted securely, you can use an HTTPS connection to access the file. Example:--login-config-cert my-cert.pem
USER_CLUSTER_KUBECONFIG
(optional) specifies the custom path to your user cluster'skubeconfig
file. The OIDC ID tokens that are returned by your OpenID provider are stored in thekubeconfig
file.Use this flag if your
kubeconfig
file resides in a location other than the default. If this flag is omitted, a newkubeconfig
file is created in the default location. Example:--kubeconfig /path/to/custom.kubeconfig
Examples:
Authenticate to specific cluster:
gcloud anthos auth login --cluster my-production-cluster
Use a prompt to select which cluster to authenticate with:
gcloud anthos auth login
Result:
Please use the --cluster flag to specify a cluster from the list below: Source: $HOME/.config/google/anthos/kubectl-anthos-config.yaml 1. Cluster: test-cluster ServerIP: https://192.168.0.1:6443 2. Cluster: test-cluster-2 ServerIP: https://192.168.0.2:6443 3. Cluster: my-production-cluster ServerIP: https://192.168.0.3:6443
Use a hosted authentication configuration file:
gcloud anthos auth login \ --cluster my-production-cluster \ --login-config HTTPS://my-secure-server/kubectl-anthos-config.yaml \ --login-config-cert my-cert.pem
Enter your credentials in the browser-based consent screen that opens.
Verify that authentication was successful by running one of the
kubectl
commands to retrieve details about your cluster. For example:kubectl get nodes --kubeconfig USER_CLUSTER_KUBECONFIG
Result: Your kubeconfig
file now contains an ID token that your kubectl
commands will use to authenticate with the Kubernetes API server on your user
cluster.
Using SSH to authenticate from a remote machine
Suppose you want to SSH into a remote machine and authenticate to a user cluster from the remote machine. To do this, your authentication configuration file must be on the remote machine, and you must be able to reach your Open ID provider from your local machine.
On your local machine, run the following command:
ssh USER_NAME@REMOTE_MACHINE -L LOCAL_PORT:localhost:REMOTE_PORT
where:
USER_NAME
andREMOTE_MACHINE
are the standard values used to log in with SSH.LOCAL_PORT
is an open port of your choice on your local machine that you will use to access the remote machine.REMOTE_PORT
is the port you configured for your OIDC redirect URL. You can find this in thekubectlRedirectURI
field of your authentication configuration file.
In your SSH shell, run the following command to initiate authentication:
gcloud anthos auth login --login-config AUTH_CONFIG_FILE
where AUTH_CONFIG_FILE
is the path of your
authentication configuration file on the remote machine.
On your local machine, in a browser, go to
http://localhost:LOCAL_PORT
/login and complete the
OIDC login flow.
Now the kubeconfig file on your remote machine has the token that you need to access the user cluster.
In your SSH shell, verify that you have access to the user cluster:
kubectl --kubeconfig USER_CLUSTER_KUBECONFIG get nodes
Authenticating through the Google Cloud console
Initiate the authentication flow from the Kubernetes clusters page in the Google Cloud console:
-
Open the Google Cloud console:
-
Locate your Google Distributed Cloud cluster in the list and then click Login.
-
Select Authenticate with the Identity Provider configured for the cluster, and then click LOGIN.
You are redirected to your identity provider, where you might need to log in or consent to the Google Cloud console accessing your account. Then you are redirected back to the Kubernetes clusters page in the Google Cloud console.
Troubleshooting your OIDC configuration
Review the following behaviors and errors to help resolve your OIDC issues:
- Invalid configuration
- If Google Cloud console cannot read the OIDC configuration from your cluster, the LOGIN button will be disabled.
- Invalid provider configuration
- If your identity provider configuration is invalid, you will see an error screen from your identity provider after you click LOGIN. Follow the provider-specific instructions to correctly configure the provider or your cluster.
- Invalid permissions
- If you complete the authentication flow, but still don't see the details of the cluster, make sure you granted the correct RBAC permissions to the account that you used with OIDC. Note that this might be a different account from the one you use to access Google Cloud console.
Error: missing 'RefreshToken' field in 'OAuth2Token' in credentials struct
- You might get this error if the authorization server prompts for consent, but
the required authentication parameter wasn't provided. Provide the
prompt=consent
parameter to Google Distributed Cloud configuration file'soidc: extraparams
field, and regenerate the client authentication file with the--extra-params prompt=consent
flag.
What's next
- Learn more about scopes and claims.