Console access for VM applications

You can open a console session to a running Linux VM application from the Red Hat Edge Manager web console or CLI. Red Hat Edge Manager supports two console types for VM applications: serial console and VNC console.

Serial console
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The serial console connects to the virtual serial port (virt-serial0) on the VM guest. This is a text-based terminal, similar to connecting a physical serial cable to a server. The serial console provides emergency debugging access when SSH is unavailable, such as during boot failures, kernel panics, or network misconfiguration.

Linux VMs output to the serial console by default. Windows guests require additional configuration: to enable serial console output on a Windows VM, configure EMS/SAC in the guest (bcdedit /ems {current} on and bcdedit /emssettings EMSPORT:1 EMSBAUDRATE:115200).

VNC console
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The VNC console provides a graphical display connection to the VM guest through the agent-mediated console path. VNC is useful for VMs that require a graphical interface or for debugging boot issues that do not produce serial output.

To open a VNC console session from the CLI:

$ flightctl app console device/<device_name> --name <vm_app_name> --type vnc

The CLI binds to a random local port for VNC forwarding by default. Use the --exposed-port flag to specify a local port instead.

Note

The Red Hat Edge Manager web console supports serial console only. To use VNC, open the session from the CLI and connect with an external VNC viewer.

Session establishment
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When you open a console session, the connection follows this path:

  1. The Red Hat Edge Manager web console or CLI opens a WebSocket connection to the flightctl-api service.
  2. The flightctl-api service routes the connection through gRPC to the Red Hat Edge Manager agent on the device.
  3. The agent connects to the VM’s virtual serial port socket (virt-serial0) for serial, or to the VNC display for VNC.
  4. The terminal or display session is established between your browser or CLI and the VM guest.

Session limits
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Only one console session of the same type can be open per VM application at a time. If a second user attempts to open a serial console session on the same application, the attempt returns HTTP 409. To take over an existing session, use the --force flag. The original session is disconnected when a new session takes over.

Access control
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Console access requires get permission on the devices/applications/console resource. Attempting to connect without this permission returns HTTP 403.

A console connection attempt returns HTTP 409 if another session of the same type is already active for the application, or if the device is in a state that prevents console access.