I'd like to add special sysctl values for an autoscaling Google Container Engine group, like nf_conntrack_max and tcp_max_syn_backlog (we run a high volume web service.) Is there a way to do this easily? I thought i'd be able to modify the startup-script in the instance template, but everything seems hardcoded.
You cannot modify the startup script in Google Container Engine, as it is used to configure docker and Kubernetes on the nodes. Your best bet is to log into each node after they have been provisioned and edit the values manually.