K
Q

Exposing a local kubernetes cluster running on a VM via the host VMs IP

8/5/2021

I have a kind kubernetes cluster running on a ubuntu VM, I have created this cluster following the documentation for enabling kubernetes ingress functionality.

This cluster has several services running inside of it, of these services there are 3 which I want to expose externally. One of these is a REST based service, the others use websocket connections.

On the host VM, after following the docs and some fiddling, I can access these services by curl'ing localhost.

I now want to expose these services via a specific interface (ens160) so that I can hit these services with some client-side automation another team has been building out.

My first attempt was to use IP tables to map traffic coming in on 80/443 to 127.0.0.1, and this works well with the REST service. 

sudo iptables -t nat -A PREROUTING -p tcp -i ens160 --dport 443 -j DNAT --to-destination 127.0.0.1:443
sudo iptables -A FORWARD -p tcp -d 127.0.0.1 --dport 443 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
sudo iptables -t nat -A PREROUTING -p tcp -i ens160 --dport 80 -j DNAT --to-destination 127.0.0.1:80
sudo iptables -A FORWARD -p tcp -d 127.0.0.1 --dport 80 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT

However the websocket connections are not establishing.

For me this method seems like a 'flimsy' approach and I am wondering if there is a better way to expose this kubernetes cluster to my 'corp network' then performing DNAT on packets coming in.

Am I going about this the wrong way?

Thanks, Max Sargent

-- max_sargent
iptables
kind
kubernetes
networking
websocket

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1 Answer

8/5/2021

I have resolved the issue, it was not related to what I had done.

By viewing the traffic I could see the connections were failing due to:

HTTP 15020: SOCKET ERROR: self signed certificate Error: self signed certificate
    at TLSSocket.onConnectSecure (node:_tls_wrap:1530:34)
    at TLSSocket.emit (node:events:394:28)
    at TLSSocket._finishInit (node:_tls_wrap:944:8)
    at TLSWrap.ssl.onhandshakedone (node:_tls_wrap:725:12)

I resolved this by setting:

rejectUnauthorized: false

In socket.io

Please close as I have resolved it myself.

Thanks, Max Sargent

-- max_sargent
Source: StackOverflow