From 8049fa9b723733f298abbe2e605b7a45241e4aa2 Mon Sep 17 00:00:00 2001
From: Brad Davidson <brad.davidson@rancher.com>
Date: Tue, 26 Nov 2024 20:06:21 +0000
Subject: [PATCH] Revert "Remove special hostname behavior for aws
 cloud-provider"

This reverts commit 89a8d81227fe12fb8ca7f4aecff22ac6834e0643.

Signed-off-by: Brad Davidson <brad.davidson@rancher.com>
(cherry picked from commit 6e701fc7d61248b17aad639c467cc2676dc6c436)
Signed-off-by: Brad Davidson <brad.davidson@rancher.com>
---
 pkg/rke2/rke2_linux.go | 64 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)

diff --git a/pkg/rke2/rke2_linux.go b/pkg/rke2/rke2_linux.go
index f0902668c4..3bf5c9e3c9 100644
--- a/pkg/rke2/rke2_linux.go
+++ b/pkg/rke2/rke2_linux.go
@@ -4,10 +4,16 @@
 package rke2
 
 import (
+	"bytes"
+	"context"
 	"fmt"
+	"io/ioutil"
+	"net/http"
+	"os/exec"
 	"path/filepath"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/k3s-io/k3s/pkg/agent/config"
 	"github.com/k3s-io/k3s/pkg/cli/cmds"
@@ -18,6 +24,7 @@ import (
 	"github.com/rancher/rke2/pkg/cli/defaults"
 	"github.com/rancher/rke2/pkg/images"
 	"github.com/rancher/rke2/pkg/podexecutor"
+	"github.com/sirupsen/logrus"
 	"github.com/urfave/cli"
 )
 
@@ -89,6 +96,19 @@ func initExecutor(clx *cli.Context, cfg Config, isServer bool) (*podexecutor.Sta
 			Name: cfg.CloudProviderName,
 			Path: cfg.CloudProviderConfig,
 		}
+		if clx.String("node-name") == "" && cfg.CloudProviderName == "aws" {
+			fqdn := hostnameFromMetadataEndpoint(context.Background())
+			if fqdn == "" {
+				hostFQDN, err := hostnameFQDN()
+				if err != nil {
+					return nil, err
+				}
+				fqdn = hostFQDN
+			}
+			if err := clx.Set("node-name", fqdn); err != nil {
+				return nil, err
+			}
+		}
 	}
 
 	if cfg.KubeletPath == "" {
@@ -469,3 +489,47 @@ func parseControlPlaneMounts(cfg Config) (*podexecutor.ControlPlaneMounts, error
 		CloudControllerManager: cfg.ExtraMounts.CloudControllerManager.Value(),
 	}, nil
 }
+
+func hostnameFQDN() (string, error) {
+	cmd := exec.Command("hostname", "-f")
+
+	var b bytes.Buffer
+	cmd.Stdout = &b
+
+	if err := cmd.Run(); err != nil {
+		return "", err
+	}
+
+	return strings.TrimSpace(b.String()), nil
+}
+
+func hostnameFromMetadataEndpoint(ctx context.Context) string {
+	ctx, cancel := context.WithTimeout(ctx, time.Second)
+	defer cancel()
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, "http://169.254.169.254/latest/meta-data/local-hostname", nil)
+	if err != nil {
+		logrus.Debugf("Failed to create request for metadata endpoint: %v", err)
+		return ""
+	}
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		logrus.Debugf("Failed to get local-hostname from metadata endpoint: %v", err)
+		return ""
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		logrus.Debugf("Metadata endpoint returned unacceptable status code %d", resp.StatusCode)
+		return ""
+	}
+
+	b, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		logrus.Debugf("Failed to read response body from metadata endpoint: %v", err)
+		return ""
+	}
+
+	return strings.TrimSpace(string(b))
+}