Managed SSH sessions are supported for Arm instances only if they run Oracle Linux
Details
Managed SSH sessions are not supported for compute instances that meet these conditions:
Created using Arm-based
OCI Ampere A1 Compute shapes.
Running an operating system other than Oracle Linux, such as Ubuntu.
To create a Managed SSH session, the Bastion plugin must be enabled and running. Because this plugin is not properly enabled on some Arm-based instances, session creation fails.
Managed SSH session fails for Ubuntu instances đź”—
Details
To create a Managed SSH session for a compute instance, the Bastion plugin must be enabled and running. This plugin is available on Oracle Cloud Agent version 1.11 or later. If your Ubuntu instance is running a version that is older than 1.11, the creation of a Managed SSH session fails.
Workaround
To update an existing Ubuntu compute instance to support Managed SSH sessions:
Add a NAT gateway to the VCN (virtual cloud network) in which you created your instance, if not already present. See Setting Up a NAT Gateway.
From your bastion, create a Managed SSH session to the instance.
If you're creating another Ubuntu instance, an alternative workaround is to provide a cloud-init script when you launch the instance. In this script, use the same command to install the latest Oracle Cloud Agent: