use softlinks to link iptables to backend specific commands and update docs

prog/weave-kube/launch.sh

@@ -28,9 +28,9 @@ setup_iptables_backend() {
       rm /sbin/iptables
       rm /sbin/iptables-save
       rm /sbin/iptables-restore
-      ln /sbin/iptables-nft /sbin/iptables
-      ln /sbin/iptables-nft-save /sbin/iptables-save
-      ln /sbin/iptables-nft-restore /sbin/iptables-restore
+      ln -s /sbin/iptables-nft /sbin/iptables
+      ln -s /sbin/iptables-nft-save /sbin/iptables-save
+      ln -s /sbin/iptables-nft-restore /sbin/iptables-restore
     fi
 }
 

prog/weave-npc/launch.sh

@@ -24,9 +24,9 @@ setup_iptables_backend() {
       rm /sbin/iptables
       rm /sbin/iptables-save
       rm /sbin/iptables-restore
-      ln /sbin/iptables-nft /sbin/iptables
-      ln /sbin/iptables-nft-save /sbin/iptables-save
-      ln /sbin/iptables-nft-restore /sbin/iptables-restore
+      ln -s /sbin/iptables-nft /sbin/iptables
+      ln -s /sbin/iptables-nft-save /sbin/iptables-save
+      ln -s /sbin/iptables-nft-restore /sbin/iptables-restore
     fi
 }
 

site/kubernetes/kube-addon.md

@@ -406,6 +406,7 @@ The list of variables you can set is:
 * `NO_MASQ_LOCAL` - set to 1 to preserve the client source IP address when
   accessing Service annotated with `service.spec.externalTrafficPolicy=Local`.
   The feature works only with Weave IPAM (default).
+* `IPTABLES_BACKEND` - set to `nft` to use `nftables` backend for `iptables` (default is `iptables`) 
 
 Example:
 ```