Accessing the RHCOS Console

Environment

• Red Hat OpenShift Container Platform (RHOCP)
  • 4
• Red Hat CoreOS (RHCOS)

Issue

• RHCOS hangs while booting and only the last 25 lines are visible in the console.
• How to access to the CoreOS console?

Resolution

The RHCOS console attaches to the consoles: console=tty0 and console=ttyS0,115200n8.

• If using vSphere, configure the virtual machine with a serial port type of "Connect via network". telnet can then be used to connect to the console.

• If using libvirt, run virsh console machine-name/id. For example, for a machine named bootstrap, run:
  virsh console bootstrap.

• If using a bare metal server , attach a null modem cable and leverage a serial terminal to interact with the emergency console.

• If you are using OpenStack or, for any other reason, you don't have access to a serial console and only to the graphical console, you should then try removing console=ttyS0,115200n8 kernel parameter while trying to access the console (keep console=tty0). Otherwise, you may face issues, like dracut console attaching to a tty you can't access.

If the boot of RHCOS fails, you will be able to interact with the emergency console and perform debug procedures:

Generating "/run/initramfs/rdsosreport.txt"


Entering emergency mode. Exit the shell to continue.
Type "journalctl" to view system logs.
You might want to save "/run/initramfs/rdsosreport.txt" to a USB stick or /boot
after mounting them and attach it to a bug report.


:/# 

Refer also to how to start RHCOS in emergency mode and How to set password for user "core" in RHCOS after OpenShift 4 cluster deployment
if you want to login using the CoreOS console.

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