UNHEALTHY | RED HAT 8

Created by Vincent Gayle, Modified on Tue, 21 Feb 2023 at 09:49 AM by Vincent Gayle

Problem: Gremlin agent reports as unhealthy in the app.gremlin.com UI when gremlin is installed on VMs with Red Hat8 OS.

Cause: Red hat removed certain kernel modules that were shipped OOTB in Red Hat 7.

Resolution: check for and install these modules with the below steps:

packages and modules to check for: iproute-tc and kernel-modules-extra(this contains the needed sch_netem module that allows for gremlin to affect the network traffic).

1. yum remove gremlin -y

2. yum install iproute-tc -y (this may be installed already. If yes, just leave it)

3. yum install kernel-modules-extra -y ( this may be installed already. just leave it.)

4. yum install gremlin gremlind -y

5. modprobe sch_netem

6. gremlin attack cpu -l 30 (document any errors)

7. gremlin attack latency -l 30 (document any errors)

8. if there is a qdisc error, reboot the server and repeat step 5.