doc(manifests): add pre settings for cluster

Signed-off-by: zhenyus <zhenyus@mathmast.com>

cluster/ansible/README.md

@@ -2,4 +2,44 @@
 
 > This folder used to Freeleaps Kubernetes Cluster maintaining.
 
+## Pre-settings for each node
+
+### Enable HugePage on node's kernel
+
+```bash
+
+# Check nodes HugePage params if not 1024
+sudo grep HugePages /proc/meminfo
+
+# Add HugePage params into kernel settings
+echo 1024 | sudo tee /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
+echo vm.nr_hugepages = 1024 | sudo tee -a /etc/sysctl.conf
+
+```
+
+### Change Kernel Params
+
+You need ensure kernel params (`/etc/sysctl.conf`) like belows:
+
+```text
+
+net.ipv4.ip_forward=1
+kernel.keys.root_maxbytes=25000000
+kernel.keys.root_maxkeys=1000000
+kernel.panic=10
+kernel.panic_on_oops=1
+vm.overcommit_memory=1
+vm.panic_on_oom=0
+net.ipv4.ip_local_reserved_ports=30000-32767
+net.bridge.bridge-nf-call-iptables=1
+net.bridge.bridge-nf-call-arptables=1
+net.bridge.bridge-nf-call-ip6tables=1
+vm.nr_hugepages = 1024
+
+```
+
+Using `sysctl -p` to make kernel params effect.
+
 ## How to use ?
+
+TODO