Introduction to Red Hat OpenShift Service on AWS (ROSA)

In the previous section, you learned how to configure your workstation and the cloud provider before creating a Red Hat OpenShift on AWS (ROSA) cluster.

In this section, you learn what cloud resources you must prepare before attempting to create a cluster. You create a ROSA cluster, and explore the resources that the cluster is composed of, such as virtual machines, disks, and load balancers.

Although you can use the Red Hat OpenShift Cluster Manager web interface to create the cloud resources and to create ROSA clusters, this section describes only the creation steps by using the command-line interface.

The ROSA cluster creation process creates Amazon Web Services (AWS) resources in your AWS account, such as Amazon Elastic Compute Cloud (EC2) instances for OpenShift cluster nodes.

ROSA relies on specific Identity and Access Management (IAM) roles and policies to grant the cluster creation process rights to create the resources. As a consequence, before you can create ROSA clusters, you must create these IAM resources.

From a command-line terminal, ensure that you used the aws configure and rosa login commands to log in to your AWS account and your Red Hat account.

Then, run the rosa create account-roles command to create the IAM resources. In automatic mode, the command uses the AWS API to create the roles and policies in your AWS account. Use the --mode auto option to activate that mode. The --yes option skips the confirmation messages before creating the resources.

$ rosa create account-roles --mode auto --yes
...output omitted...
I: Creating account roles
I: Creating roles using 'arn:aws:iam::...:user/user1@example.com-fqppg-admin'
I: Created role 'ManagedOpenShift-Installer-Role' ...
I: Created role 'ManagedOpenShift-ControlPlane-Role' ...
I: Created role 'ManagedOpenShift-Worker-Role' ...
I: Created role 'ManagedOpenShift-Support-Role' ...
I: To create a cluster with these roles, run the following command:
rosa create cluster --sts

In manual mode, the rosa create account-roles command generates the roles and policies in files on your local system, but does not create them in AWS. This method is useful if your IAM user does not have enough permissions to create the IAM resources in the AWS account. You can send the files to your AWS administrators to apply them in the AWS account. Use the --mode manual option to activate that mode.

$ rosa create account-roles --mode manual
...output omitted...
I: Creating account roles
I: All policy files saved to the current directory
I: Run the following commands to create the account roles and policies:

aws iam create-role \
	--role-name ManagedOpenShift-Installer-Role \
	--assume-role-policy-document file://sts_installer_trust_policy.json \
	--tags Key=rosa_openshift_version,Value=4.12 Key=rosa_role_prefix,Value=ManagedOpenShift Key=rosa_role_type,Value=installer Key=red-hat-managed,Value=true

aws iam create-policy \
	--policy-name ManagedOpenShift-Installer-Role-Policy \
	--policy-document file://sts_installer_permission_policy.json	--tags Key=rosa_openshift_version,Value=4.12 Key=rosa_role_prefix,Value=ManagedOpenShift Key=rosa_role_type,Value=installer Key=red-hat-managed,Value=true

aws iam attach-role-policy \
	--role-name ManagedOpenShift-Installer-Role \
	--policy-arn arn:aws:iam::452954386616:policy/ManagedOpenShift-Installer-Role-Policy
...output omitted...

If you do not provide the --mode option, then the command interactively asks for the mode to use.

After preparing the cloud environment, you are ready to create a ROSA cluster.

From a command-line terminal, run the rosa create cluster command to initiate the creation of your ROSA cluster. The command triggers the cluster creation and then exits. It does not wait for the installation to complete. Instead, the cluster creation process runs unattended on AWS.

By default, the rosa create cluster command runs in interactive mode. You need to specify only the cluster name, and you can accept the default values that the command suggests for the other parameters.

$ rosa create cluster
I: Enabling interactive mode
? Cluster name: mycluster
? Deploy cluster using AWS STS: Yes
W: In a future release STS will be the default mode.
W: --sts flag won't be necessary if you wish to use STS.
W: --non-sts/--mint-mode flag will be necessary if you do not wish to use STS.
? OpenShift version: 4.12.14
I: Using arn:...:role/ManagedOpenShift-Installer-Role for the Installer role
I: Using arn:...:role/ManagedOpenShift-ControlPlane-Role for the ControlPlane role
I: Using arn:...:role/ManagedOpenShift-Worker-Role for the Worker role
I: Using arn:...:role/ManagedOpenShift-Support-Role for the Support role
? External ID (optional): <Enter>
? Operator roles prefix: mycluster-p5k3  
? Multiple availability zones (optional): No
? AWS region: us-east-1
? PrivateLink cluster (optional): No
...output omitted...
I: Creating cluster 'mycluster'
I: To create this cluster again in the future, you can run:  
   rosa create cluster --cluster-name mycluster --sts --role-arn arn:aws:iam::452954386616:role/ManagedOpenShift-Installer-Role --support-role-arn arn:aws:iam::452954386616:role/ManagedOpenShift-Support-Role --controlplane-iam-role arn:aws:iam::452954386616:role/ManagedOpenShift-ControlPlane-Role --worker-iam-role arn:aws:iam::452954386616:role/ManagedOpenShift-Worker-Role --operator-roles-prefix mycluster-p5k3 --region us-east-1 --version 4.12.14 --compute-nodes 2 --compute-machine-type m5.xlarge --machine-cidr 10.0.0.0/16 --service-cidr 172.30.0.0/16 --pod-cidr 10.128.0.0/14 --host-prefix 23
I: To view a list of clusters and their status, run 'rosa list clusters'
I: Cluster 'mycluster' has been created.
I: Once the cluster is installed you will need to add an Identity Provider before you can login into the cluster. See 'rosa create idp --help' for more information.
...output omitted...
I: Run the following commands to continue the cluster creation:  

	rosa create operator-roles --cluster mycluster
	rosa create oidc-provider --cluster mycluster

I: To determine when your cluster is Ready, run 'rosa describe cluster -c mycluster'.
I: To watch your cluster installation logs, run 'rosa logs install -c mycluster --watch'.
$

You can also run the command in automatic mode by adding the --mode auto --sts options. In that mode, the command uses default parameter values and automatically creates the additional IAM resources.

You can overwrite a parameter by specifying its value as a command-line option. For example, use the --compute-nodes 3 option for creating three compute nodes instead of two by default. Run the rosa create cluster --help command to list the available options.

$ rosa create operator-roles --cluster mycluster
...output omitted...
I: Created role 'mycluster-p5k3-openshift-machine-api-aws-cloud-credentials' ...

$ rosa create oidc-provider --cluster mycluster
...output omitted...

$ rosa describe cluster --cluster mycluster
...output omitted...
State:      installing
...output omitted...

$ rosa describe cluster --cluster mycluster
...output omitted...
State:      ready
...output omitted...

ROSA builds your OpenShift clusters by using AWS resources. To help you to identify these resources, ROSA prefixes their names with the cluster name.

$ aws ec2 describe-instances --filters "Name=tag:Name,Values=mycluster*"

$ aws ec2 describe-vpcs --filters "Name=tag:Name,Values=mycluster*"

$ aws ec2 describe-subnets --filters "Name=tag:Name,Values=mycluster*"

$ aws elbv2 describe-load-balancers

Inspect the Resources from the AWS Management Console

You can also list the AWS resources for your ROSA cluster from the AWS Management Console at https://console.aws.amazon.com/.

Important

When you use the AWS Management Console, be sure to select the correct region for your ROSA cluster. Otherwise, you might not find the AWS resources that you are looking for.

Figure 1.10: Select the AWS Region

The AWS Management Console organizes the resources into AWS services:

• To list the EC2 instances, navigate to Services → Compute → EC2 and then select Instances → Instances.

  

  Figure 1.11: Access the EC2 service

• To list the VPC resources, navigate to Services → Networking & Content Delivery → VPC and then select Virtual private cloud → Your VPCs.

• To list the subnets inside the VPC, select Virtual private cloud → subnets.

• To list the ELB resources, navigate to Services → Compute → EC2 and then select Load Balancing → Load Balancers.

After creation, the ROSA cluster does not provide a user account that you can use to start deploying applications. The following sections present how you can create an initial user account to test your new cluster, and how to configure your cluster to use an external identity provider for user authentication.

References

For more information about creating a ROSA cluster, refer to the Creating a Cluster Using Customizations section in the Creating a ROSA Cluster with STS Using Customizations chapter in the Red Hat OpenShift Service on AWS 4 Installing, Accessing, and Deleting ROSA Clusters documentation at https://access.redhat.com/documentation/en-us/red_hat_openshift_service_on_aws/4/html-single/installing_accessing_and_deleting_rosa_clusters/index#rosa-sts-creating-cluster-using-customizations_rosa-sts-creating-a-cluster-with-customizations

For more information about the required IAM roles, refer to the About IAM Resources for ROSA Clusters that Use STS chapter in the Red Hat OpenShift Service on AWS 4 Introduction to ROSA documentation at https://access.redhat.com/documentation/en-us/red_hat_openshift_service_on_aws/4/html-single/introduction_to_rosa/index#rosa-sts-about-iam-resources

AWS - CLI Command Reference