The boot node and the bastion host

When you start a Suite installation, a boot node is created that controls and completes the installation. In the OpenShift cluster, a bastion host is created to allow Secure Shell (SSH) access to cluster nodes.

During a Suite installation on AWS, virtual private clouds (VPC) are created that contain Amazon EC2 instances. For example, a VPC is created to contain the OpenShift cluster, and EC2 instances are created in the cluster to represent its master and worker nodes.

The two most important EC2 instances that are created during an installation are the boot node and the bastion host.

The boot node

In the AWS cloud, after you specify the installation parameters and start the installation, a boot node is created. The installation parameters are passed to the boot node. In addition, all of the required tools to complete the installation, such as Terraform and Docker, are installed on the boot node. By using these tools and parameters, the boot node performs the following tasks to complete the installation:

• Creates the virtual network infrastructure, such as the VPC that will contain the OpenShift cluster.
• Runs the bootstrap process that creates the OpenShift cluster.
• Installs the Suite prerequisites.
• Installs the Suite.
• Performs any required postinstallation validation.
• Stores the installation context and Terraform state files both locally and in the Amazon S3 storage bucket that is associated with your AWS account.

Because it is located in its own VPC, the boot node is not part of the Suite's OpenShift cluster. After the installation is complete, you do not need to use the boot node to access the cluster or interact with the Suite. For this reason, the boot node is kept in a shutdown state. However, if required, you can restart it and use it to troubleshoot installation issues.

The bastion host

The VPC that the boot node creates contains several public and private subnets. In one of the public subnets, a bastion host is created. By using this host, you can connect to the cluster nodes in the private subnets.

After the installation is complete, the bastion host is kept in a shutdown state. However, you can restart it if you want to access cluster nodes by using SSH. For more information, see the Accessing the boot node and OpenShift cluster topic.

In addition, if required, you can delete the bastion host and create your own.

Note: No charges apply to Amazon EC2 instances that are in a shutdown state, such as the boot node and the bastion host. However, charges apply for their attached EBS GP2 volumes of 10 GB. For more information, see Amazon EBS pricing in the AWS documentation.