From dcd671c4546d737f4a984437c979bbdc08a42745 Mon Sep 17 00:00:00 2001
From: "marcoemi.poleggi" <marco-emilio.poleggi@hesge.ch>
Date: Fri, 8 Nov 2024 11:12:21 +0100
Subject: [PATCH] Update README.md with socat port-forwarding trick
---
README.md | 34 +++++++++++++++++++++++++++++++++-
1 file changed, 33 insertions(+), 1 deletion(-)
diff --git a/README.md b/README.md
index ff8864c..b69b5c1 100644
--- a/README.md
+++ b/README.md
@@ -248,6 +248,11 @@ First, check the **External IP** of the load balancer:
kubectl get service loadbalancer
```
+:bulb: Thanks to JSON output, you can get directly the IP address with the command:
+```bash
+kubectl get service loadbalancer -o=jsonpath='{.status.loadBalancer.ingress[0].ip}')
+```
+
Then, write a shell script that sends some (at least 10) HTTP requests in a loop via `curl`.
Run your script: it should show HTTP reponses from two different IP addresses. It might take some time to show output from both instances, as metallb is not a round-robin-style load balancer.
@@ -331,4 +336,31 @@ However it is possible to [set up an SSH "tunnel"](https://www.ssh.com/academy/s
```bash
workstation$ kubectl get services
```
-
\ No newline at end of file
+
+ ### Expose the loadbalancer's external IP address
+
+As we have seen, with our cluster setup, the loadbalancer's external IP address is not routable outside the KinD host.
+Without further complicating the MetalLB configuration, we can expose this address via the `socat` program,
+which can do TCP-port forwarding.
+
+1. Install `socat` on your remote KinD host:
+ ```bash
+ kind$ apt install socat
+ ```
+1. Set up TCP-port-forwarding from the loadbalancer's external IP to the host's public IP:
+ ```bash
+ kind$ LB_IP=$(kubectl get service loadbalancer -o=jsonpath='{.status.loadBalancer.ingress[0].ip}')
+ kind$ nohup sudo socat -ly tcp-listen:80,reuseaddr,fork "tcp:${LB_IP}:80" &
+ kind$ sudo sh -c "echo $! > /var/run/socat.pid"
+ ```
+
+Now you should be able to connect to your Web service from the outside:
+```bash
+workstation$ $ curl KIND_HOST_IP:80
+Hello from Kubernetes! My IP is 10.244.1.4
+```
+
+To stop the socat port forwarding, issue:
+```bash
+kind$ sudo sh -c "kill $(cat /var/run/socat.pid)"
+```
--
GitLab