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Using manual mode with STS - Managing cloud provider credentials | Authentication and authorization | OpenShift Container Platform 4.8
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Using manual mode with Amazon Web Services Secure Token Service

Manual mode with STS is supported for Amazon Web Services (AWS).

This credentials strategy is supported for only new OpenShift Container Platform clusters and must be configured during installation. You cannot reconfigure an existing cluster that uses a different credentials strategy to use this feature.

About manual mode with AWS Secure Token Service

In manual mode with STS, the individual OpenShift Container Platform cluster components use AWS Secure Token Service (STS) to assign components IAM roles that provide short-term, limited-privilege security credentials. These credentials are associated with IAM roles that are specific to each component that makes AWS API calls.

Requests for new and refreshed credentials are automated by using an appropriately configured AWS IAM OpenID Connect (OIDC) identity provider, combined with AWS IAM roles. OpenShift Container Platform signs service account tokens that are trusted by AWS IAM, and can be projected into a pod and used for authentication. Tokens are refreshed after one hour.

Detailed authentication flow between AWS and the cluster when using AWS STS
Figure 1. STS authentication flow

Using manual mode with STS changes the content of the AWS credentials that are provided to individual OpenShift Container Platform components.

AWS secret format using long-lived credentials
apiVersion: v1
kind: Secret
metadata:
  namespace: <target-namespace> (1)
  name: <target-secret-name> (2)
data:
  aws_access_key_id: <base64-encoded-access-key-id>
  aws_secret_access_key: <base64-encoded-secret-access-key>
1 The namespace for the component.
2 The name of the component secret.
AWS secret format with STS
apiVersion: v1
kind: Secret
metadata:
  namespace: <target-namespace> (1)
  name: <target-secret-name> (2)
stringData:
  credentials: |-
    [default]
    role_name: <operator-role-name> (3)
    web_identity_token_file: <path-to-token> (4)
1 The namespace for the component.
2 The name of the component secret.
3 The IAM role for the component.
4 The path to the service account token inside the pod. By convention, this is /var/run/secrets/openshift/serviceaccount/token for OpenShift Container Platform components.

Installing an OpenShift Container Platform cluster configured for manual mode with STS

To install a cluster that is configured to use the Cloud Credential Operator (CCO) in manual mode with STS:

  1. Configure the Cloud Credential Operator utility.

  2. Create the required AWS resources individually, or with a single command.

  3. Run the OpenShift Container Platform installer.

  4. Verify that the cluster is using short-lived credentials.

Because the cluster is operating in manual mode when using STS, it is not able to create new credentials for components with the permissions that they require. When upgrading to a different minor version of OpenShift Container Platform, there are often new AWS permission requirements. Before upgrading a cluster that is using STS, the cluster administrator must manually ensure that the AWS permissions are sufficient for existing components and available to any new components.

Configuring the Cloud Credential Operator utility

To create and manage cloud credentials from outside of the cluster when the Cloud Credential Operator (CCO) is operating in manual mode with STS, extract and prepare the CCO utility (ccoctl) binary.

The ccoctl is a Linux binary that must run in a Linux environment.
Procedure

  1. Obtain the OpenShift Container Platform release image.

    $ RELEASE_IMAGE=$(./openshift-install version | awk '/release image/ {print $3}')

  2. Get the CCO container image from the OpenShift Container Platform release image:

    $ CCO_IMAGE=$(oc adm release info --image-for='cloud-credential-operator' $RELEASE_IMAGE)

    Ensure that the architecture of the $RELEASE_IMAGE matches the architecture of the environment in which you will use the ccoctl tool.

  3. Extract the ccoctl binary from the CCO container image within the OpenShift Container Platform release image:

    $ oc image extract $CCO_IMAGE --file="/usr/bin/ccoctl" -a ~/.pull-secret

  4. Change the permissions to make ccoctl executable:

    $ chmod 775 ccoctl
Verification

  • To verify that ccoctl is ready to use, display the help file:

    $ ccoctl aws --help
    Output of ccoctl aws --help:
    Creating/updating/deleting cloud credentials objects for AWS cloud


Usage:
  ccoctl aws [command]


Available Commands:
  create-all               Create all the required credentials objects
  create-iam-roles         Create IAM roles
  create-identity-provider Create IAM identity provider
  create-key-pair          Create a key pair
  delete                   Delete credentials objects

Flags:
  -h, --help   help for aws

Use "ccoctl aws [command] --help" for more information about a command.

Creating AWS resources with the Cloud Credential Operator utility

You can use the CCO utility (ccoctl) to create the required AWS resources individually, or with a single command.

Creating AWS resources individually

If you need to review the JSON files that the ccoctl tool creates before modifying AWS resources, or if the process the ccoctl tool uses to create AWS resources automatically does not meet the requirements of your organization, you can create the AWS resources individually. For example, this option might be useful for an organization that shares the responsibility for creating these resources among different users or departments.

Otherwise, you can use the ccoctl aws create-all command to create the AWS resources automatically.

By default, ccoctl creates objects in the directory in which the commands are run. To create the objects in a different directory, use the --output-dir flag. This procedure uses <path_to_ccoctl_output_dir> to refer to this directory.

Some ccoctl commands make AWS API calls to create or modify AWS resources. You can use the --dry-run flag to avoid making API calls. Using this flag creates JSON files on the local file system instead. You can review and modify the JSON files and then apply them with the AWS CLI tool using the --cli-input-json parameters.
Prerequisites

  • Extract and prepare the ccoctl binary.

Procedure

  1. Generate the public and private RSA key files that are used to set up the OpenID Connect provider for the cluster:

    $ ccoctl aws create-key-pair
    Example output:
    2021/04/13 11:01:02 Generating RSA keypair
2021/04/13 11:01:03 Writing private key to /<path_to_ccoctl_output_dir>/serviceaccount-signer.private
2021/04/13 11:01:03 Writing public key to /<path_to_ccoctl_output_dir>/serviceaccount-signer.public
2021/04/13 11:01:03 Copying signing key for use by installer

    where serviceaccount-signer.private and serviceaccount-signer.public are the generated key files.

    This command also creates a private key that the cluster requires during installation in /<path_to_ccoctl_output_dir>/tls/bound-service-account-signing-key.key.

  2. Create an OpenID Connect identity provider and S3 bucket on AWS:

    $ ccoctl aws create-identity-provider \
--name=<name> \
--region=<aws_region> \
--public-key-file=<path_to_ccoctl_output_dir>/serviceaccount-signer.public

    where:

    • <name> is the name used to tag any cloud resources that are created for tracking.

    • <aws-region> is the AWS region in which cloud resources will be created.

    • <path_to_ccoctl_output_dir> is the path to the public key file that the ccoctl aws create-key-pair command generated.

    Example output:
    2021/04/13 11:16:09 Bucket <name>-oidc created
2021/04/13 11:16:10 OpenID Connect discovery document in the S3 bucket <name>-oidc at .well-known/openid-configuration updated
2021/04/13 11:16:10 Reading public key
2021/04/13 11:16:10 JSON web key set (JWKS) in the S3 bucket <name>-oidc at keys.json updated
2021/04/13 11:16:18 Identity Provider created with ARN: arn:aws:iam::<aws_account_id>:oidc-provider/<name>-oidc.s3.<aws_region>.amazonaws.com

    where 02-openid-configuration is a discovery document and 03-keys.json is a JSON web key set file.

    This command also creates a YAML configuration file in /<path_to_ccoctl_output_dir>/manifests/cluster-authentication-02-config.yaml. This file sets the issuer URL field for the service account tokens that the cluster generates, so that the AWS IAM identity provider trusts the tokens.

  3. Create IAM roles for each component in the cluster.

    1. Extract the list of CredentialsRequest objects from the OpenShift Container Platform release image:

      $ oc adm release extract \
--credentials-requests \
--cloud=aws \
--to=<path_to_directory_with_list_of_credentials_requests>/credrequests (1)
--from=quay.io/<path_to>/ocp-release:<version>
      1 credrequests is the directory where the list of CredentialsRequest objects is stored. This command creates the directory if it does not exist.

    2. Use the ccoctl tool to process all CredentialsRequest objects in the credrequests directory:

      $ ccoctl aws create-iam-roles \
--name=<name> \
--region=<aws_region> \
--credentials-requests-dir=<path_to_directory_with_list_of_credentials_requests>/credrequests \
--identity-provider-arn=arn:aws:iam::<aws_account_id>:oidc-provider/<name>-oidc.s3.<aws_region>.amazonaws.com

      For AWS environments that use alternative IAM API endpoints, such as GovCloud, you must also specify your region with the --region parameter.

      For each CredentialsRequest object, ccoctl creates an IAM role with a trust policy that is tied to the specified OIDC identity provider, and a permissions policy as defined in each CredentialsRequest object from the OpenShift Container Platform release image.

Verification

  • To verify that the OpenShift Container Platform secrets are created, list the files in the <path_to_ccoctl_output_dir>/manifests directory:

    $ ll <path_to_ccoctl_output_dir>/manifests
    Example output:
    total 24
-rw-------. 1 <user> <user> 161 Apr 13 11:42 cluster-authentication-02-config.yaml
-rw-------. 1 <user> <user> 379 Apr 13 11:59 openshift-cloud-credential-operator-cloud-credential-operator-iam-ro-creds-credentials.yaml
-rw-------. 1 <user> <user> 353 Apr 13 11:59 openshift-cluster-csi-drivers-ebs-cloud-credentials-credentials.yaml
-rw-------. 1 <user> <user> 355 Apr 13 11:59 openshift-image-registry-installer-cloud-credentials-credentials.yaml
-rw-------. 1 <user> <user> 339 Apr 13 11:59 openshift-ingress-operator-cloud-credentials-credentials.yaml
-rw-------. 1 <user> <user> 337 Apr 13 11:59 openshift-machine-api-aws-cloud-credentials-credentials.yaml

You can verify that the IAM roles are created by querying AWS. For more information, refer to AWS documentation on listing IAM roles.

Creating AWS resources with a single command

If you do not need to review the JSON files that the ccoctl tool creates before modifying AWS resources, and if the process the ccoctl tool uses to create AWS resources automatically meets the requirements of your organization, you can use the ccoctl aws create-all command to automate the creation of AWS resources.

Otherwise, you can create the AWS resources individually.

By default, ccoctl creates objects in the directory in which the commands are run. To create the objects in a different directory, use the --output-dir flag. This procedure uses <path_to_ccoctl_output_dir> to refer to this directory.
Prerequisites

  • Extract and prepare the ccoctl binary.

Procedure

  1. Extract the list of CredentialsRequest objects from the OpenShift Container Platform release image:

    $ oc adm release extract \
--credentials-requests \
--cloud=aws \
--to=<path_to_directory_with_list_of_credentials_requests>/credrequests \ (1)
--from=quay.io/<path_to>/ocp-release:<version>
    1 credrequests is the directory where the list of CredentialsRequest objects is stored. This command creates the directory if it does not exist.

  2. Use the ccoctl tool to process all CredentialsRequest objects in the credrequests directory:

    $ ccoctl aws create-all \
--name=<name> \
--region=<aws_region> \
--credentials-requests-dir=<path_to_directory_with_list_of_credentials_requests>/credrequests
Verification

  • To verify that the OpenShift Container Platform secrets are created, list the files in the <path_to_ccoctl_output_dir>/manifests directory:

    $ ll <path_to_ccoctl_output_dir>/manifests
    Example output:
    total 24
-rw-------. 1 <user> <user> 161 Apr 13 11:42 cluster-authentication-02-config.yaml
-rw-------. 1 <user> <user> 379 Apr 13 11:59 openshift-cloud-credential-operator-cloud-credential-operator-iam-ro-creds-credentials.yaml
-rw-------. 1 <user> <user> 353 Apr 13 11:59 openshift-cluster-csi-drivers-ebs-cloud-credentials-credentials.yaml
-rw-------. 1 <user> <user> 355 Apr 13 11:59 openshift-image-registry-installer-cloud-credentials-credentials.yaml
-rw-------. 1 <user> <user> 339 Apr 13 11:59 openshift-ingress-operator-cloud-credentials-credentials.yaml
-rw-------. 1 <user> <user> 337 Apr 13 11:59 openshift-machine-api-aws-cloud-credentials-credentials.yaml

You can verify that the IAM roles are created by querying AWS. For more information, refer to AWS documentation on listing IAM roles.

Running the installer

Prerequisites

  • Obtain the OpenShift Container Platform release image.

Procedure

  1. Change to the directory that contains the installation program and create the install-config.yaml file:

    $ openshift-install create install-config --dir <installation_directory>

    where <installation_directory> is the directory in which the installation program creates files.

  2. Edit the install-config.yaml configuration file so that it contains the credentialsMode parameter set to Manual.

    Example install-config.yaml configuration file
    apiVersion: v1
baseDomain: cluster1.example.com
credentialsMode: Manual (1)
compute:
- architecture: amd64
  hyperthreading: Enabled
...
    1 This line is added to set the credentialsMode parameter to Manual.

  3. Create the required OpenShift Container Platform installation manifests:

    $ openshift-install create manifests

  4. Copy the manifests that ccoctl generated to the manifests directory that the installation program created:

    $ cp /<path_to_ccoctl_output_dir>/manifests/* ./manifests/

  5. Copy the private key that the ccoctl generated in the tls directory to the installation directory:

    $ cp -a /<path_to_ccoctl_output_dir>/tls .

  6. Run the OpenShift Container Platform installer:

    $ ./openshift-install create cluster

Verifying the installation

  1. Connect to the OpenShift Container Platform cluster.

  2. Verify that the cluster does not have root credentials:

    $ oc get secrets -n kube-system aws-creds

    The output should look similar to:

    Error from server (NotFound): secrets "aws-creds" not found

  3. Verify that the components are assuming the IAM roles that are specified in the secret manifests, instead of using credentials that are created by the CCO:

    Example command with the Image Registry Operator
    $ oc get secrets -n openshift-image-registry installer-cloud-credentials -o json | jq -r .data.credentials | base64 --decode

    The output should show the role and web identity token that are used by the component and look similar to:

    Example output with the Image Registry Operator
    [default]
role_arn = arn:aws:iam::123456789:role/openshift-image-registry-installer-cloud-credentials
web_identity_token_file = /var/run/secrets/openshift/serviceaccount/token