Add net.ipv4.ip_forward=1 and use ansible sysctl.

Signed-off-by: Lantao Liu <lantaol@google.com>

contrib/ansible/cri-containerd.yaml

@@ -17,13 +17,14 @@
       systemd: name=cri-containerd daemon_reload=yes state=started enabled=yes
 
     - name: "Set bridge-nf-call-iptables" 
-      lineinfile:
-        line: "net/bridge/bridge-nf-call-iptables = 1"
-        dest: /etc/sysctl.conf
-        insertafter: 'EOF'
-        regexp: '\/net\/bridge\/bridge-nf-call-iptables = 1'
-        state: present
-      ignore_errors: true
+      sysctl:
+        name: net.bridge.bridge-nf-call-iptables
+        value: 1
+
+    - name: "Set ip_forward" 
+      sysctl:
+        name: net.ipv4.ip_forward
+        value: 1
 
     - name: "Check kubelet args in kubelet config"
       shell: grep "^Environment=\"KUBELET_EXTRA_ARGS=" /etc/systemd/system/kubelet.service.d/10-kubeadm.conf